Kenwood TS-870S MF/HF Transceiver
Contents
1. 72 February 1996 Table 1 Kenwood TS 870 serial no 70500128 Manufacturer s Claimed Specifications Measured in the ARRL Lab Frequency coverage Receive 100 kHz 30 MHz Receive 30 kHz to 30 MHz transmit as specified transmit 1 8 2 3 5 4 7 7 3 10 1 10 15 14 14 35 18 068 18 168 21 21 45 24 89 24 99 28 29 7 MHz Modes of operation USB LSB CW AM FM FSK As specified Power requirement Receive 2 A no signal Receive 2 A no signal transmit 16 5 A max tested at 13 8 V transmit 20 5 A max Receiver Receiver Dynamic Testing SSB CW sensitivity bandwidth not specified Minimum discernible signal noise floor 400 Hz WIDTH and 700 Hz SHIFT 10 dB S N N 100 500 kHz 1 V 500 kHz Preamp off Preamp on 1 7 MHz 4 V 1 7 24 5 MHz 0 2 V 1 0 MHz 108 dBm 117 dBm 24 5 30 MHz 0 13 V 3 5 MHz 131 dBm 141 dBm 14 MHz 129 dBm 139 dBm AM sensitivity 10 dB S N N bandwidth not specified 10 dB S N N 1 kHz tone 30 modulation 6 kHz WIDTH 100 500 kHz 2 V 0 5 1 7 MHz 32 V Preamp off Preamp on 1 7 30 MHz 2 V 1 0 MHz 35 V 76 dBm 11 V 86 dBm 3 8 MHz 2 3 V 100 dBm 0 7 V 110 dBm FM sensitivity 12 dB SINAD 28 30 MHz 0 25 V For 12 dB SINAD 14 kHz bandwidth Preamp off Preamp on 29 MHz 0 9 V 108 dBm 0 16 V 123 dBm Blocking dynamic range Not specified Blocking dynamic range 400 Hz WIDTH Pre2. adapter board These pots are not accessible with out removing the cover however As you might suspect the adapter is a bit of a compromise The offset is fixed at roughly 700 Hz at the factory To change it you need a frequency counter or a general coverage receiver The 700 Hz offset was fine for me but it might be unacceptable to other operators IF bandwidth is the same as for SSB The MFJ 415 adapter does not provide full break in QSK In addition keying was somewhat harsh The roughness was notice able but in my opinion not objectionable However a CW purist might cringe at ev ery dit and dah Also we discovered during 76 February 1996 Figure 5 CW keying waveform for the MFJ 9420 in the semi break in mode showing the first and second dits The upper trace is the actual key closure the lower trace is the RF envelope Horizontal divisions are 10 ms The transceiver was being operated at approximately 8 W output at 14 2 MHz Note the significant shortening and slower rise time of the first dit Figure 4 Spectral display of the MFJ 9420 transmitter during two tone intermodulation distortion IMD testing Third order product is approximately 19 dB below PEP output and the fifth order product is approximately 28 dB down The transceiver was being operated at approximately 8 W PEP output at 14 2 MHz Figure 6 Spectral display of the MFJ 9420 transmitter output during composite noise testing Power output is ap
3. antenna tuner A five pin DIN type micro phone connector a backlighted analog S meter and two LEDs round out the collec tion That s it On the rear panel you find an SO 239 antenna jack dc power connector microphone level control and if you install the MFJ 415 CW adapter a button to en able CW operating and a key jack An inter nal speaker graces the top of the cabinet The MFJ 9420 receiver is a single con version superheterodyne A four pole bandpass filter at the input functions as an effective preselector for 20 meter signals The active mixer stage converts the signals to the 10 MHz IF From there a crystal lad der filter sets the IF bandwidth before the signals are applied to a single chip IF am plifier Another IC acts as the product de tector and its output drives yet another chip which functions as an audio preamp and filter AGC is audio derived and can be adjusted internally The final audio amp drives the speaker directly providing plenty of room filling volume although the output as measured by the ARRL Lab fell a tad short of the specified 1 W or so In the transmitter a microphone speech amplifier drives a balanced modulator and a filter then removes the lower sideband and carrier The MFJ 9420 operates in upper sideband only After undergoing a healthy amount of dynamic compression more about this later the USB signal is routed to the transmitter mixer RF predriver driver and final output stage
4. the manual at hand as you make your menu selections at least at first because the abbreviated word dis play can be a bit cryptic Among many other things the menus let you set or adjust AGC release times for various modes CW rise and decay times CW pitch speech processor frequency re sponse panel brightness and various DSP parameters DSP Goodies Four pushbuttons along the upper right hand side of the front panel access the radio s DSP functions AUTO NOTCH BEAT CANCEL N R and TX EQ The first three are adaptive filters that can identify various interfering signals or noise and modify their filtering characteristics based on the par ticular noise or interference You can switch between SPAC or Line Enhance using a menu selection Auto notch only works in SSB mode This DSP filter identi fies interfering tones in the receiver pass band and attenuates them Beat cancel works in both SSB and AM and is similar to the auto notch filter but can be more effective for some types of tones Some reviewers lamented the lack of beat cancel or manual notch for CW ARRL Lab tests found beat cancel was more effective against multiple heterodynes than auto notch which only worked well against a single heterodyne The DSP noise reduction system oper ates in any mode and effectively reduces random background noise It s a bit like an analog noise blanker the TS 870S has one of those too but it seems more effective than
5. 5 SP 31 external speaker 99 95 Manufacturer Kenwood Commu nications Corp P O Box 22745 Long Beach CA 90801 5745 tel 310 639 5300 February 1996 75 Table 2 MFJ 9420 Travel Radio 20 Meter SSB Transceiver Manufacturer s Claimed Specifications Measured in the ARRL Lab Frequency coverage Receive 14 150 14 350 MHz Receive and transmit 14 153 SSB 14 0 14 100 CW transmit not specified 14 344 MHz SSB 14 0 14 145 MHz CW Modes of operation USB and CW with CW adapter As specified Power requirement Receive 100 mA typical max Receive 109 mA transmit 1 8 A tested transmit 2 2 A max at 13 8 V at 13 8 V Receiver Receiver Dynamic Testing SSB CW sensitivity bandwidth not specified Minimum discernible signal 0 6 V 12 dB S N lt 0 5 V 113 dBm 131 dBm Blocking dynamic range Not specified 103 dB Two tone third order IMD dynamic range 82 dB Third order intercept point Not specified 8 dBm Second order intercept point 77 dBm S meter sensitivity Not specified S9 signal 115 V Receiver audio output gt 1 W at 10 THD into 8 0 6 W at 10 THD into 8 Spurious and image rejection Not specified IF rejection 55 dB image rejection 99 dB Transmitter Transmitter Dynamic Testing Power output CW 8 10 W SSB 10 W PEP CW and SSB 8 W Spurious signal and harmonic suppression 45 dB Meets FCC requirements for Not specified spectral purity SSB carrie
6. 83 MHz to pass through a 3 or 6 kHz filter or through no filter in FM The signal is then shifted to 455 kHz where it passes through a 3 6 or 15 kHz filter Finally the signal is mixed down to 11 3 kHz and applied to the DSP s analog to digital converter The various oscillators that set the mixing frequencies are all digitally controlled and that turns out to be important The TS 870S uses a time honored technique to achieve adjustable bandwidth and IF shift by varying these oscillator frequencies so that one side of the receiver passband is set by the 8 83 MHz filter and the other side by the 455 kHz filter The resulting band limited signal then is demodulated by the DSP It is also bandpass filtered by the DSP and the DSP generates the AGC voltage Since both the oscillators used for mixing and the DSP unit are digitally controllable the TS 870S can adjust the analog passband and the digital passband in tandem Consider what this means If the TS 870S relied only on DSP to narrow the receiver s passband signals outside the DSP filter but inside the analog passband would pound away at the IF circuitry possibly causing gain compression blocking and or IMD generation On the other hand if the TS 870S relied only on the analog filters to set the passband strong signal performance wouldn t be as bad but you wouldn t have the advantage of the brick wall shape of a DSP filter s frequency response But the TS 870S uses both kinds
7. I doubt that I was pushing many receiver meters beyond S 5 but my signal was strong enough that I rarely had to repeat an exchange I shut down at 2130 UTC with 32 contacts in the log slightly more than one contact per minute Not bad for a radio that you can hold in one hand WB8IMY Conclusion The MFJ 9420 is a terrific little trans ceiver for casual 20 meter operating With a small power supply or rechargeable bat tery pack you can take it anywhere Al Table 3 JPS ANC 4 Antenna Noise Canceller Manufacturers Claimed Specifications Measured in the ARRL Lab Operating frequency range 100 kHz to 80 MHz As specified Noise cancellation 40 dB or greater typical As specified Signal loss from main antenna 6 dB As specified Maximum RF input to main antenna 3 V rms As specified Maximum RF transmit power through unit As specified Tested at 14 MHz for 150 W PEP approximately 5 mins Time to switch to bypass when transmit RF 6 ms is detected 7 ms typical Time to return to receive when transmit RF 600 ms JPS new includes a is removed 500 ms typical resistor to cut hang time to 7 ms if desired Power requirements 11 to 16 V dc at 150 mA 75 mA at 13 8 V Size height width depth 1 7 6 4 3 inches Weight 2 lb though it s promoted as a travel radio the 9420 is fine for home use especially for a low profile station It also was a pleasure to work 20 meter phone without tearing up my TV and telephon
8. Product Review Column from QST Magazine Copyright 1996 by the American Radio Relay League Inc All rights reserved February 1996 Kenwood TS 870S MF HF Transceiver MFJ 9420 20 Meter SSB Travel Radio JPS ANC 4 Antenna Noise Canceller Product Review Edited by Rick Lindquist KX4V Assistant Technical Editor February 1996 71 Reviewed by Larry Wolfgang WR1B Senior Assistant Technical Editor With the introduction of the TS 870S Kenwood helps usher in a new era in Ama teur Radio equipment design As do the lat est offerings from ICOM and Yaesu Kenwood s newest MF HF transceiver in cludes digital signal processing DSP at IF but with a difference Kenwood s competi tors take the belt and suspenders approach and couple crystal filters both standard and optional with DSP on their latest radios but the TS 870S requires no additional crys tal filters to supplement its DSP It s the first radio in its class to make that claim To better understand how the TS 870S implements DSP at HF see the sidebar DSP in the Kenwood TS 870S Features The TS 870S s attractive but no non sense front panel has the complement of controls you would expect on any full fea tured HF rig But not all of this radio s goodies are obvious at first glance The prominent main tuning knob has a soft rubber grip that provides a comfortable feel and a handy finger depression to spin up or down the band You can set the tuni
9. aboratory offers a 30 page test result report on the TS 870S that gives in depth detailed technical data on the transceiver s performance outlines our test methods and helps you to interpret the numbers and graphs The report also includes spectral purity charts and receiver sensitivity figures for all bands all CW keying waveforms not just worst case and other facts to help you make an informed buying decision The report even includes a summary of how this radio stacks up with similar previously tested units Request the TS 870S Test Result Report from the ARRL Technical Department at 7 50 for ARRL members and 12 50 for nonmembers postpaid February 1996 73 memory channels to make bandhopping and frequency swapping a breeze Unlike its DSP competitors the ICOM IC 775DSP or the Yaesu FT 1000MP the Kenwood TS 870S does not have dual receive capa bility You can transmit or receive on either VFO or a memory channel however Press the appropriate buttons in the RX and TX columns to the right of the MODE buttons to make a selection A small LED lights in each active button A single memory chan nel can store separate transmit and receive frequencies as well as mode information The inability to store filter settings in any memory channel or band register was a common complaint from reviewers how ever It seems odd in a radio this sophisti cated that you can t save a particular filter setting with a certain frequency but t
10. amp off Preamp on 1 0 MHz 128 dB 124 dB 3 5 MHz 127 dB 124 dB 14 MHz 127 dB 123 dB Two tone third order IMD dynamic range Not specified Two tone third order IMD dynamic range 400 Hz WIDTH Preamp off Preamp on 1 0 MHz 83 dB 89 dB 3 5 MHz 99 dB 95 dB 14 MHz 97 dB 95 dB Third order input intercept Not specified Preamp off Preamp on 1 0 MHz 17 dBm 17 dBm 3 5 MHz 18 dBm 2 dBm 14 MHz 16 dBm 4 dBm Second order intercept point Not specified Preamp off 63 dBm preamp on 63 dBm FM adjacent channel rejection Not specified 88 dB at 20 kHz channel spacing 29 MHz FM two tone third order IMD dynamic range Preamp off 84 dB preamp on 79 dB at 20 kHz channel spacing 29 MHz Not specified S meter sensitivity Not specified S9 signal at 14 MHz preamp off 176 V preamp on 50 V Squelch sensitivity Not specified At threshold preamp on FM 0 03 V SSB 1 3 V Receiver audio output 1 5 W at 10 THD into 8 2 4 W at 10 THD into 8 IF audio response Not specified Range at 6 dB points band width CW N 400 Hz WIDTH 700Hz SHIFT 489 906 Hz 417 Hz CW W 1000 Hz WIDTH 700 Hz SHIFT 195 1203 Hz 1008 Hz USB W LO 300 Hz HI 3000 Hz 230 2988 Hz 2758 Hz USB N LO 400 Hz HI 1800 Hz 391 1804 Hz 1413 Hz LSB W LO 300 Hz HI 3000 Hz 225 2967 Hz 2742 Hz LSB N LO 400 Hz HI 1800 Hz 386 1798 Hz 1412 Hz Notch filter depth 40 dB or more As specified Spurious and
11. and down the band making contact after con tact I even managed to fight my way through a small pileup and work a station in Morocco The only annoyance was the in ability to narrow the receive bandwidth An audio filter would be a big help February 1996 77 Reviewed by Emil Pocock W3EP ARRL Technical Advisor Voodoo electronics That was my first reaction after hearing the JPS ANC 4 com pletely eliminate loud computer hash in the middle of 40 meters It is also remarkably effective in reducing the radio frequency interference generated by nearby power lines electric motors televisions and many home electronic devices Typical noise blankers and limiters of ten are ineffective in dealing with many of these problems Even when they do reduce interference from pulse type radio sources noise blankers create another difficulty Strong adjacent signals can trigger the au tomatic gain control effectively reducing the receiver s dynamic range The ANC 4 avoids this problem by removing many types of local noise before the offending signals enter the receiver Desired signals previously buried in the noise magically stand out in a much quieter receiver pass band when using the ANC 4 Description The ANC 4 is enclosed in a rather weighty two piece black steel box It easily installs JPS ANC 4 Antenna Noise Canceller Bottom Line The ANC 4 is remarkable in reducing local RF noise on a wide range of frequencies and modes To
12. antenna to the TS 870S such as a Beverage for 80 or 160 meters is not possible without internal modifications The TS 870S does not have a built in AC power supply It needs 13 8 V dc at 20 5 A If you don t already own a suitable supply add that cost to the price of the radio The Complete Radio I have yet to find the perfect radio at a price I could afford We could consider the TS 870S to be the complete radio however Except for the required power supply the TS 870S is ready to go as it comes out of the box It doesn t need addi tional IF filters an external audio DSP unit or an external memory keyer Available matching accessories fall under the head ing of nice to have rather than need to have Perhaps Dave Newkirk summed it up best Nits aside the TS 870S is a great be ginning for something new in Amateur Ra dio Radios with IF DSP that do IF filter ing IF DSP that s teamed with AGC performance that needs no apology and that produces the stellar receive audio today s best analog designs can only approximate Thanks to these hams who contributed operating impressions and comments for this review Rick Lindquist KX4V Dave Newkirk WJ1Z Glenn Swanson KB1GW Jon Bloom KE3Z Mike Gruber WA1SVF Tom Frenaye K1KI and his contest team and Emil Pocock W3EP Manufacturer s suggested retail prices TS 870S 3199 95 MC 90 desktop micro phone 269 95 PS 52 heavy duty power supply 309 9
13. ays present in the 8 83 MHz IF stages no matter what LO SHIFT or HI WIDTH settings you use The radio uses two Motorola DSP56002 DSP chips which represent a lot of processing capability This allows the demodulation and filtering functions to be combined with adaptive filters for noise reduction and automatic notching In transmit the TS 870S uses the DSP system to generate the modulated signal which is then mixed up to the output frequency through several stages The DSP also processes the transmitted audio including speech compression and VOX and generates the CW sidetone and the radio s various control beeps a nice economy of circuitry Why not use the DSP instead of building a beep oscillator The TS 870S does a good job of integrating DSP technology into an HF transceiver While any technology can be improved the scheme used by Kenwood takes good advantage of the possibilities of digital signal processing If provision were made for optional 500 Hz crystal filters the combination of analog and DSP performance would be nearly ideal Jon Bloom KE3Z gram four front panel buttons ENTER TF SET 1MHz and FINE to handle other functions you might find more useful Or you can disable them altogether if you want The TS 870S Instruction Manual is 100 plus pages chock full of clearly written and easy to understand information and oper ating tips It even includes a brief DSP tuto rial Plenty of diagrams help you identify various con
14. boundaries Each mode change selects the last used filter setting for that mode You can t store particular filter settings with the boundaries however The built in automatic antenna tuner is supposed to match impedances between 20 and 150 The tuner certainly does a good job matching a resonant antenna beyond its normal bandwidth but it won t work miracles I found it helpful for matching my dipoles and triband Yagi over the entire band Near band edges where the SWR tends to climb the tuner could provide a near perfect match Another feature reviewers found espe cially useful was the quick memory Say you re not having any luck trying to break the DX pileup and want to come back a bit later to try again Just hit the M IN button You can store up to five frequencies this way To recall them hit the MR button Turn the M CH VFO CH knob to step through the five quick memory channels Data move through these channels in a first in first out fashion so when you store a sixth frequency the first one is pushed out of the register and lost Using menu selections you can repro 74 February 1996 DSP in the Kenwood TS 870S Like the rest of the current crop of DSP equipped amateur MF HF transceivers the TS 870S performs digital signal processing at a low IF about 11 3 kHz in this case On receive the signal is first mixed to 73 05 MHz and passed through the 15 kHz wide roofing filter then shifted down to 8
15. defeat local noise before it reaches your transceiver s antenna jack the ANC 4 is hard to beat Phone Sweepstakes 1995 The 30 Minute Sprint If you re going to put a new transceiver through a baptism of pure hellfire the ARRL November Sweepstakes is the best time to do it This contest draws a tidal wave of phone and CW operators on two separate weekends Unfortunately family activities knocked me out of the CW slugfest another operator easily worked a half dozen or so stations with the 9420 however and I could only spare a half hour for the phone brawl If I was going to properly abuse the MFJ 9420 figuratively speaking it would have to be within the first 30 minutes of the contest I jumped in with both feet at 2100 UTC starting at 14 150 MHz and working my way up I began hunting and pouncing on the strongest stations and this strategy paid off right away The big guns didn t always answer my first call but I usually attracted their attention by my third or fourth appeal Despite the RF pandemonium everyone seemed to copy me well The 9420 s receiver also did an adequate job of distilling relative order from chaos A number of stations expressed amazement when I told them I was QRP Using the microphone gain control I had reduced the output to slightly less than 5 W PEP true QRP One fellow in Minnesota thought I was pulling his leg You re kicking my meter up to S 9 You can t be running QRP with just a dipole
16. e antenna size and placement will vary with circumstances The ANC 4 works best when the noise antenna is close to the noise source Lab tests showed the unit especially needed a strong noise signal above 30 MHz to effectively cancel it So if the problem is a furnace blower it may help to place the antenna near the furnace and connect it to the ANC 4 via coaxial cable Its effective ness against power line noise may be in creased by placing several feet of noise antenna parallel to some house wiring or even laying the noise antenna on the ground beneath the errant power lines The ANC 4 also can be used in a mobile setup In that case the manual suggests routing a wire noise antenna into the engine compartment to insure good pickup of offending ignition and alternator noise Other Uses The ANC 4 also can serve as an active antenna In that mode no antenna is con nected to the main antenna jack Instead the top mounted whip or a short wire serves as the main receiving antenna and the NOISE GAIN control adjusts the amplifi cation of the received signals With some experimentation the ANC 4 also can be used for diversity reception You connect a second antenna of opposite polarization or separated by several wavelengths from the main to the noise antenna jack Then you adjust the controls to combine signals from both antennas so they are in phase The ANC 4 also can be used to create a receiv ing antenna system with a hi
17. ency edges of the combined filter response reduce the ef fective bandwidth Kenwood calls this tech nique slope tuning Purely from an oper ating point of view our reviewers would have preferred to have the filters continu ously tunable in an analog fashion But Kenwood s implementation virtually de mands a limited number of digital steps You may have to twiddle the two knobs and adjust the AGC time con stant to obtain the best performance But this design means that strong signals close to your desired receive frequency espe cially on CW may cause some blocking Turning on AIP and adding some attenua tion may help I didn t experience any interference that couldn t be acceptably reduced using the TS 870S s various adjustments On the other hand tests in the ARRL Lab con firmed that strong close in signals could produce troublesome IMD and degrade dynamic range in the TS 870S Our in house receiver guru Dave Newkirk WJ1Z asserts that Kenwood s fil tering scheme produces the best receive audio I ve heard in an Amateur Radio prod uct One reason Dave goes on to say is that the TS 870S receiver has excellent immu nity to in passband IMD Another reason he says is that the TS 870S s combination of linked variable IF bandwidth and DSP IF filtering gives you maximal control over how much of an incoming signal the radio converts to audio If you want you can re ceive SSB wi
18. es You won t bust many DX pileups with the 9420 nor win any contests but you will work more stations than you might imag ine and have a heck of a good time while you re at it I wonder if anyone has earned their phone DXCC with this radio Hmmm If you re at all inclined to operate CW the MFJ 415 adapter is worth the additional cost Even with the adapter the MFJ 9420 is still within most hams budgets In fact the MFJ 9420 could be an excellent starter radio for new hams licensed at General class or higher as long as they understand the nature of QRP operating and have realistic expectations As I ve already mentioned a headphone jack would be a welcome addition For CW operating an external audio filter also would substantially enhance the perfor mance Nitpicking aside the MFJ 9420 is a fun radio that has more than a few sur prises in store for jaded hams such as my self Manufacturer MFJ Enterprises PO Box 494 Mississippi State MS 39762 tel 800 647 1800 Suggested list prices MFJ 9420 transceiver 229 95 MFJ 415 CW adapter 39 95 between the station antenna and receiver or transceiver A short collapsible whip which mounts through a hole on top of the unit serves as a built in noise sensing an tenna On the rear apron are UHF connectors for MAIN ANTENNA and RADIO receiver or transceiver a phono jack for an optional ie external wire NOISE ANTENNA and a coaxial dc power jack An
19. gh front to back ratio Such a system requires a second antenna that s similar to the main one but separated from it by at least half a wave length In this case you use the NOISE PHASE adjustment to null signals arriving from the unwanted direction The controls and noise antenna place ment can be critical but once you find op timal operating conditions the unit gener ally requires no further adjustment within a given amateur band Its use does not affect the dynamic range or other performance features of the main receiver Thanks to Charles Michaels W7XC and Rick Lindquist KX4V for contributing to this review Manufacturers suggested retail price February 1996 79 175 Manufacturer JPS Communications PO Box 97757 Raleigh NC 27624 tel 919 790 1048 fax 919 790 1456 SOLICITATION FOR PRODUCT REVIEW EQUIPMENT BIDS In order to present the most objective re views ARRL purchases equipment off the shelf from dealers ARRL receives no remu neration from anyone involved with the sale or manufacture of items presented in the Prod uct Review or New Products columns Ed The ARRL purchased Product Review equipment listed below is for sale to the high est bidder Prices quoted are minimum accept able bids and are discounted from the purchase prices All equipment is sold without warranty Alinco DX 70T MF HF VHF transceiver see Product Review December 1995 QST Minimum bid 759 ICOM IC 775DSP MF HF t
20. he radio does remember what filter setting you used last with each mode UP and DOWN buttons let you switch bands in sequence or with the 1MHZ button activated change frequency in 1 MHz steps instead Additionally a ten key multifunc tion keypad allows direct frequency entry as well as storing memory data selecting scan functions and controlling the memory keyer features In VFO mode you use the M CH VFO CH control to make large fre quency excursions within a band in steps of 1 5 or 10 kHz menu settable For split frequency operation you sim ply select one VFO or memory channel for receive and the other VFO or memory channel for transmit Or you can program a memory channel with both frequencies If you select different VFOs or memory data for transmit and receive you press and hold the TF SET button and use the main tuning knob to set your transmit frequency One reviewer who was used to the typi cal split button found this a bit confus ing It does take getting used to The Figure 2 CW keying waveform for the TS 870S in the semi break in mode showing the first and second dits The upper trace is the actual key closure the lower trace is the RF envelope Horizon tal divisions are 10 ms The transceiver was being operated at 100 W output at 14 2 MHz Figure 1 Worst case spectral display of the TS 870S transmit ter during two tone intermodulation distortion IMD testing The third order product is appr
21. icates current filter bandwidth and relative frequency shift This portion of the display lacks numbers so you can t tell the exact filter settings For that information you ll have to look at the right side of the display window and you may have to first turn the appropriate filter select knob to activate the readout In trans mit this same meter section displays SWR ALC or speech compression level Turning on the P HOLD menu selection holds peak readings on both bar graphs for about 2 5 seconds Most users liked the display window and its colorful legends The bright white main display numerals are about a half inch high and easy to read Red labels above the frequency display indicate active func tions such as AGC MONItor and speech PROCessor Yellow labels below the fre quency display indicate the active mode One reviewer commented that the unlighted LED segments remain distractingly visible behind the display window lens A darker display window lens could lesser the effect The ANT button selects between two rear panel antenna connectors ATT UP and DOWN buttons select either 0 6 12 or 18 dB of receive attenuation AIP Advanced In tercept Point also available with the touch of a button helps to reduce inter modulation distortion by throttling back the sensitivity On a band crowded with strong signals you ll likely want to leave AIP on Getting Around with the 870S The 870S has two VFOs plus 100
22. ids ARRL 225 Main St Newington CT 06111 1494
23. image rejection 80 dB or better Preamp off 98 dB preamp on 114 dB IF rejection 80 dB or better Preamp off 115 dB preamp on 124 dB Transmitter Transmitter Dynamic Testing Power output SSB CW FSK FM 100 W max CW typically 113 W max lt 1 W min SSB 118 W max lt 1 W min 20 W or less min continuously adjustable AM 25 W varies slightly from band to band AM typically 24 W max max 20 W or less min continuously adjustable lt 1 W min FM typically 109 W max 9 W min Spurious signal and harmonic suppression 60 dB or more lt 60 dBc on all amateur bands Meets FCC requirements for spectral purity SSB carrier suppression 50 dB or more As specified Undesired sideband suppression 50 dB or more As specified Third order intermodulation distortion IMD See Figure 1 products Not specified CW keyer speed range 6 60 wpm As specified CW keying characteristics Not specified See Figure 2 Transmit receive turnaround time PTT release to S9 signal 14 ms 50 audio output Not specified Receive transmit turnaround time tx delay 15 ms Composite transmitted noise Not specified See Figure 3 Size height width depth 4 7 13 13 inches weight 25 pounds Note Dynamic range measurements were made at the ARRL Lab standard signal spacing of 20 kHz Measurement was noise limited at the value indicated Expanded Product Review Test Results Report Available The ARRL L
24. io button controls and pull down menus make the program easy to navigate In addition many contesters like to use contest software packages like CT or NA to run their stations It s easy with the TS 870S just connect a 9 pin modem cable and let your software do the rest CW Ops Only CW ops will revel in the TS 870S s built in full featured Logikey K 1 memory keyer controlled from the front panel The keyer was a favorite among the CW enthu siasts who tried the radio This is the CMOS Super Keyer II as seen in Novem ber 1990 QST and featured in recent ARRL Handbooks It s a lot of fun to play with and the Operator s Manual devotes six pages to it The available speed range is about 6 to 60 wpm settable in ranges refer enced on 20 wpm The keyer includes four message memories that can call each other and that can send automatic serial numbers for contesting Unless you re using an amplifier it s best to turn off the loud clacking amplifier switching keying relay a menu option The FULL SEMI button selects full QSK or semi break in CW operation Other Features If you d like the TS 870S lets you pro gram a set of boundary conditions for use with its automatic mode In this case as you tune the radio say from the phone portion of the band into the frequency range used for digital modes and then into the CW re gion the radio automatically selects the appropriate mode You can set up to 19 such
25. ly had taken it on faith that operating sideband QRP was next to impossible Part of the secret of the 9420 s success is the hefty amount of speech processing it uses By watching the output meter I could tell that my average power level was barely fluctuating I asked the fellow how I sounded and he simply described the audio as punchy At least it didn t sound as though the rig was trying to suck the room into the microphone along with my voice I enjoyed similar conversations and sig nal reports with other hams in the US South America and Europe As long as the band remained stable and interfering sta tions kept their distance I could talk as long as I liked Generally speaking I was able to work any station I could receive at moder ate strength S5 or greater on the 9420 s meter I even managed to bag some of the weaker ones but with difficulty CW operating with the MFJ 9420 takes a little practice You need time to perfect your zero beating skills for example You don t have the luxury of an RIT control to assist And don t forget that the offset is adjustable only by recalibrating the adapter You also must acclimate yourself to the clattering relay Hams accustomed to silent T R switching may find themselves dis tracted at first But after a few minutes on the air I hardly noticed the noise Running CW with the 9420 was every bit as enjoyable as operating phone During one Sunday afternoon I prowled up
26. ng steps to 5 or 10 kHz per revolution The FINE tun ing button divides this value by 10 when it is turned on but you cannot display the 1 Hz units to go along with the fine tuning steps With the small tuning steps the radio sounds almost analog as you tune None of that digital warbling as the VFO changes frequency Two groups of four controls apiece some of them concentric flank the tuning knob and give ready access to the most used functions Better yet the knobs and associ ated pushbuttons are substantial enough for even the most fumble fingered ops to get a grip on them To the left of the main tuning knob one set of concentric controls adjusts the built in electronic keyer speed and AGC attack speed Turning the AGC knob fully counter clockwise turns off the AGC there is no detent or other tactile response to let you know when the AGC is off so you ll have to look on the display for the red AGC legend above the main frequency readout Other concentric controls in this group set the speech processor and monitor volume lev els adjust CW AM or FSK carrier level or SSB output with the speech processor on set VOX delay and adjust microphone gain Bottom Line The first DSP transceiver without standard or optional narrow crystal IF filters the TS 870S offers fine receive and transmit audio noteworthy selectivity and comfortable controls A snazzy computer control program and interface are standard Kenwo
27. od TS 870S MF HF Transceiver and power output level Convenient pushbuttons just above these knobs select the transmit metering function options are ALC SWR compres sion level and output power and activate the speech processor and monitor function The right hand group of controls in cludes single knob controls for RIT XIT and M CH VFO CH to change the memory chan nel or VFO channel plus concentric con trols to set AF or RF level and NB noise blanker and SQL squelch A CLEAR pushbutton quickly zeros the incremental tuning As you adjust the RIT the main fre quency display also changes to show the actual receive frequency The display window conveys plenty of information about the radio s operating sta tus Is the AGC on How about the speech processor The automatic antenna tuner All these questions and more are easily answered at a glance For example one spot in the display window shows DSP filter high or low frequency limits for phone modes filter bandwidth for FSK and filter center frequency or bandwidth for CW This in formation shares display space with RIT or XIT tuning increment data as well as with the transmit frequency in split The left side of the display window is a digital LCD representation of an analog meter complete with an arc In receive the top of the display is an S meter In trans mit the same segments indicate output power In receive the lower portion of the display graphically ind
28. of filtering That means the receiver s ultimate passband is set by the DSP filters but signals outside the DSP filter passband are attenuated by the analog filters The results of this tradeoff are particularly noticeable in CW To achieve a typical CW passband of 400 or 600 Hz the analog filters are shifted so that their pass bands overlap only by the desired amount But between the filters in the mix down to 455 kHz a full 3 kHz wide swath of signals the signals that pass through the 8 83 MHz filter is present This means that signals within this 3 kHz wide band but outside of the desired passband may cause blocking or generate IMD For an explanation of this effect see Putting Variable Bandwidth Tuning Back into Late Model ICOM IC 751A Transceivers Hints and Kinks April 1991 QST We found this to be the case with the TS 870S For example blocking dynamic range degrades by 10 dB or so when a signal appears inside the 8 83 MHz filter as compared to the same signal appearing outside that filter Older non DSP Kenwood designs allowed for inclusion of narrow crystal filters typically 500 Hz wide in the IF stages These created a narrow passband with a good shape factor which simply isn t the case when using one IF to set the high edge of the passband and the other IF to set the low edge The DSP in the TS 870S takes care of the shape factor but the lack of a narrow crystal filter means that a wide bandwidth signal is alw
29. onor on our guest room night stand I assumed that it would end up in a similar location in a hotel fishing cabin or wherever My first surprise came when I stretched out on the bed and switched on the radio I expected muddy audio and a few signals here and there Not so The 9420 s receiver was re markably sensitive and selective I spent considerable time listening to everything from DX pileups to traffic nets The VFO is touchy so you must tune very slowly If you become too eager you ll find yourself zipping through a dozen signals in one twist of the knob Receive audio was abundant but that advantage soon turned into a curse If the MFJ 9420 is truly a go anywhere rig how do you prevent your fellow travelers from being inundated by a symphony of signals I often have a sleeping toddler in the next room If I awaken her it s my duty to get her back to sleep The obvious answer was headphones but I quickly discovered that the 9420 lacks a headphone jack I grabbed a jack from my junk box and improvised eventually creating a pig tail assembly that protruded from the back panel I couldn t bring myself to drill a hole in a new radio After assuming a comfortable position on the guest bed once again I began search ing for phone contacts I answered a CQ from a ham in Scotland who gave me a 56 report Impressive When I told him what I was running I could hear the astonishment in his voice As I once had he simp
30. oximately 32 dB below PEP output and the fifth order product is approximately 47 dB down The transceiver was being operated at 100 W PEP output at 14 2 MHz Figure 3 Worst case spectral display of the TS 870S transmit ter output during composite noise testing Power output is 100 W at 3 5 MHz The carrier off the left edge of the plot is not shown This plot shows composite transmitted noise 2 to 22 kHz from the carrier right side of the display shows the transmit frequency and the word SPLIT in small red letters above it There is no other indica tion One contest group that used the radio liked the fact that the 870S displayed both receive and transmit frequencies but felt it was too easy to transmit on the wrong fre quency Would You Like a Menu As we ve suggested all the 870S s fea tures are not obvious at first glance They re hidden within a menu system that our review team found easy to use The MENU button provides access to dozens of user definable operating parameters while the M CH VFO CH button selects the appropri ate menu item Two identical menu banks 68 items each let you define two com pletely different sets of operating condi tions This is useful for operators who want the radio to perform one way for contesting or DXing but yet another for rag chewing or operating digital modes Ham families using the same radio also might find the two menu banks helpful You ll want to have
31. proximately 8 W at 14 2 MHz The carrier off the left edge of the plot is not shown This plot shows composite transmitted noise 2 to 22 kHz from the carrier ARRL Lab tests that even a high resistance 1 M or so across the key terminals would key the transmitter possibly posing a prob lem for some keyers The point to keep in mind is that the MFJ 415 adapter adds value to the 9420 transceiver by almost doubling the fre quency coverage and adding a second mode The casual operator the person this transceiver was designed for will prob ably be willing to forgive the adapter s faults in view of its benefits On The Air They call the MFJ 9420 a travel radio so I decided to get into the spirit of the de sign No I didn t pack it into a suitcase although I could have with plenty of room to spare I cut a wire dipole antenna and center fed it with RG 58 coax One end of the dipole was about 40 feet up in a back yard maple tree The opposite end was an chored to the roof of my tool shed about 8 feet off the ground I was careful to trim the antenna for a 1 1 SWR because the 9420 design does not include foldback circuitry to protect the RF output transistor an MRF 477 that MFJ describes as bullet proof MFJ says it tolerates a 3 1 VSWR and accidental feedline shorts or opens Be sides at such low power levels you can t afford to waste power in the feed line The MFJ 9420 occupied a place of h
32. r suppression Not specified 40 dB Undesired sideband suppression Not specified 46 dB Third order intermodulation distortion products See Figure 4 Not specified CW keying characteristics Not specified See Figure 5 Transmit receive turnaround time PTT release to S9 signal 78 ms 50 audio output Not specified Receive transmit turnaround time tx delay 18 ms Composite transmitted noise Not specified See Figure 6 Size height width depth 2 5 6 5 6 inches weight 2 lb Reviewed by Steve Ford WB8IMY Managing Editor I used to think that operating SSB on the HF bands with only 10 W was a fool s game As far as I was concerned low power ham ming was strictly the province of CW lov ers After all the ability of a CW signal to be heard under virtually any condition makes it an ideal mode for low power At tempting the same thing with an SSB signal with its highly variable audio characteris tics and broad as a barn bandwidth seemed like a grand waste of time It s funny how we carry certain assump tions for years without really putting them to the test I was due for a wake up call in the form of the MFJ 9420 transceiver Back to Basics It s difficult to find an SSB transceiver that s more basic than the MFJ 9420 The tiny radio features only four controls VFO POWER ON OFF VOLUME and TUNE ON OFF The TUNE ON OFF button lets you put out a reduced power carrier for an external
33. ransceiver with optional filters FL 222 FL 223 and FL 102 sold as a package only see Product Re view January 1996 QST Minimum bid 2855 MFJ 411 Pocket Morse Tutor see Product Review December 1995 QST Minimum bid 50 morsix Codeman mt 5 Morse code trainer see Product Review December 1995 QST Minimum bid 102 Sealed bids must be submitted by mail and must be postmarked on or before March 1 1995 Bids postmarked after the closing date will not be considered Bids will be opened seven days after the closing postmark date In the case of equal high bids the high bid bearing the earliest postmark will be declared the suc cessful bidder In your bid clearly identify the item you are bidding on using the manufacturer s name and model number or other identification number if specified Each item requires a separate bid and envelope Shipping charges will be paid by ARRL Please include a day time telephone number The successful bidder will be advised by telephone with a confirma tion by mail No other notifications will be made and no information will be given to any one other than successful bidders regarding final price or identity of the successful bidder If you include a self addressed stamped post card with your bid and you are not the high bidder on that item we will return the postcard to you when the unit has been shipped to the successful bidder Please send bids to Bob Boucher Product Review B
34. s follow The MFJ 9420 is designed to generate MFJ 9420 20 Meter SSB Travel Radio Bottom Line Impressive performance in an economical go anywhere low power transceiver that s loads of fun to use about 10 W average speech output My unit cranked out approximately 8 W This is not QRP by strict definition 5 W PEP or less Sticklers can crank down the micro phone level to achieve true QRP That s just what I did during the 1995 November Sweepstakes with interesting results See the sidebar Phone Sweepstakes 1995 The 30 Minute Sprint Power requirements are simple 12 V at 2 A I used a Radio Shack regulated dc supply and it didn t even break a sweat You could also use a rechargeable gel cell battery MFJ 415 CW Adapter Unwilling to explore 20 meters with one hand behind my back I decided to add the MFJ 415 CW adapter The adapter is a small L shaped circuit board that installs atop the primary transceiver board Instal lation is straightforward and takes less than a half hour You secure the board on stand off posts and mate two small connectors The adapter expands frequency cover age down to 14 0 MHz simply by adding capacitance to the VFO tank circuit When you key the transceiver the adapter unbal ances the balanced modulator resulting in a carrier on the desired frequency Nothing too complicated about that The keying de lay and sidetone volume are adjustable through potentiometers on the
35. th no detectable other side of zero beat response and an audio passband that s flat from nearly 0 to beyond 6 kHz The TS 870S Dave says lets you tai lor your receive passband to match that of transmitted signals and the resulting high quality sound can be a revelation Dave deplored the small size and poor audio fi delity of the built in speaker To take best advantage of the received audio quality a good external speaker is a must Computer Control Kenwood packages its Radio Control Program software with the TS 870S This nifty Windows application lets you com pletely control the radio from your com puter A graphical representation of the ra dio is right there on the screen and you can push its buttons and twiddle its knobs with your mouse or other pointing device Click ing on the telegraph key graphic brings up a text screen where you enter text and click the key button to send it You can even store and load text files with canned messages It s that simple Using the computer radio interconnec tion via the built in RS 232 port you can literally create your own user interface Don t like the position of the main tuning knob No problem Just move it Prefer a radio with a different shape or with cus tomized controls You ve got it You can design display and operate the radio of your dreams It is fun to experiment with this software The familiar Windows drag and drop edit ing rad
36. the typical noise blanker which is best at combating pulse type noise Some re viewers were disappointed the noise reduc tion was not front panel adjustable as it is on competing transceivers as well as on many add on DSP boxes A menu choice lets you adjust the optimal correlation time for best reception using NR The TX EQ button lets you apply high frequency boost bass boost or comb filter ing to your transmitted phone signal accord ing to a menu setting Other menu settings also let you tweak transmitted audio char acteristics In other words you can tailor your transmitted audio characteristics to better match your voice microphone fre quency response and room acoustics Re viewers got good audio signal reports dur ing on air testing The transmitted audio did not seem distorted even with 10 dB of speech compression cranked in As ex pected the processor did add extra punch to the signal Now to the heart of the matter the two small knobs LO WIDTH and HI SHIFT that adjust the DSP filter settings For phone reception the LO WIDTH knob selects the low frequency cutoff and the HI SHIFT knob selects the high frequency cutoff On CW and FSK the LO WIDTH knob selects the bandwidth while the HI SHIFT knob sets the IF shift in CW But watch out Using the menu you can change CW pitch or offset and if you select a narrow filter bandwidth and adjust the IF shift it s possible to move the received signal clean o
37. trols and connections Sche matic diagrams are on two 23 32 inch folded sheets and there s a smaller block diagram No one on the review team even men tioned cooling fan noise with the TS 870 Indeed it s hard to tell when it s running The Dark Side There s nothing particularly remarkable about the radio s rear panel except a lack of clutter There are two antenna jacks plus connections for a keyer paddle a straight key or external keying device external speaker amplifier connections accessory connector for a multimode communications processor MCP for RTTY packet and other digital modes and a 9 pin RS 232 computer interface connector I was glad to see a ground lug with a wing nut and wash ers rather than a push in terminal for a solid wire that some radios call a ground connection A phono jack provides the 8 83 MHz IF signal for connection to a station monitor Fortunately Kenwood supplies the 13 pin DIN plug accessory connector for an MCP since it would no doubt be difficult to find one otherwise Soldering connections to this plug is no picnic however The spac ing between pins is one tenth of an inch so solder bridges and stray wire strand prob lems happen easily You d think the phono jack labeled EXT RX ANT is for an external receive antenna but you d be wrong This jack lets you con nect a second receiver to the 870S Kenwood concedes that connecting a sepa rate receive
38. ut of the pass band For example if CW pitch is set to 500 Hz and the bandwidth is 100 Hz with the IF shift at 700 Hz you won t be able to tune the received signal for zero beat All reviewers liked the ability to easily and quickly adjust DSP filter characteris tics Several commented on the operation of these controls Both give positive tactile feedback you can feel them click as you rotate them each click representing another step in the DSP filtering These steps seem optimal for SSB but at times too large for other modes where several reviewers longed for finer control For example you can select CW filter bandwidths of 1000 600 400 200 100 and even 50 Hz In FSK available bandwidths are 1500 1000 500 or 250 Hz At times one bandwidth seemed too wide and the next one too narrow While running RTTY for example I would have preferred a bandwidth somewhere between 500 and 250 Hz especially while tuning for stations CW operators expressed similar sentiments A peek at the Service Manual sheds some light on what happens inside the radio when you turn these knobs and perhaps offers an explanation for the digital steps The radio s microprocessor selects IF filter combinations based on the LO WIDTH and HI SHIFT settings In addition the micro processor sends control signals to the PLL and DDS local oscillator circuits By chang ing the LO frequency the signal is shifted so the high and low frequ
39. ut the general idea is to increase the NOISE GAIN until some per ceptible change is noted then to vary the NOISE PHASE knob until you null the noise Changing the frequency and phase range switches sometimes helped but there was no way to know in advance what settings would achieve optimal results Once found further adjustment was not needed while tuning as much as several hundred kilohertz from the initial frequency The ANC 4 did a remarkable job of eliminating the simultaneous noise from my computer television and telephone an swering machine which are scattered about the house I brought my especially noisy computer down to the shack as if for con test logging or to run a packet station The ANC 4 had no trouble knocking out all traces of the S9 noise on any band Below 10 MHz the insertion loss was hardly per ceptible However at 50 MHz where CW or SSB signals might be very weak the insertion loss was noticeable Even so be ing able to take out 50 dB of local noise generally justified the one S unit or so loss of signal strength The top mounted whip prevent you from putting the unit below a shelf or other over hang I found a wire noise antenna much more flexible since its length and place ment often made all the difference to good performance especially at higher frequen cies I eventually settled on a 10 foot wire stretched across the ceiling in the basement shack as optimal for 28 and 50 MHz but the nois
40. y 12 V source delivering up to 150 mA will do JPS can supply a 120 V ac adapter The adjustable NOISE PHASE and NOISE GAIN controls are on the front panel along with PHASE RANGE and FRE QUENCY RANGE pushbuttons The ANC 4 has a built in RF sensing relay so it can be used with a transceiver The ANC 4 is designed to reduce only 78 February 1996 locally generated RF noise and does little to reduce noise from distant sources in cluding static The unit performs its magic by comparing two signal sources The first originating primarily via the main antenna contains the desired signals plus the un wanted RF noise The second arriving via the noise sensing antenna consists mostly of the undesired RF noise which is am plified and passed through an adjustable phase shift network You set the NOISE GAIN control so noise from the noise an tenna just equals noise from the main an tenna Then you adjust the phase shift network with the NOISE PHASE control until the two noise sources are 180 out of phase The two signals enter a hybrid com biner where the noise components cancel each other The desired signal coming almost exclusively from the main an tenna passes through the combiner with some loss but is otherwise unaffected Performance Adjusting the NOISE PHASE and NOISE GAIN controls to achieve complete noise cancellation was sometimes tricky espe cially above 15 MHz The two controls in teract to some extent b
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