| G3YRO |
Rating:  |
2023-09-26 | |
| Excellent Transceiver, Just do simple mods. |
Time Owned: more than 12 months. |
I decided to buy a flagship synthesized Transceiver about 7 years ago, but wanted something I could fix myself. I decided on a TS-930S, as unlike all the later rigs, all the ICs are still available, as are the PA Transistors. And all the other transistors can be replaced with readily-available similar types.
There is nothing really bad about the PSU - just a silly design flaw. The fact that Kenwood disconnect its output from the rig when you turn off the Mains can cause a Transient which may destroy the Pass Transistors.
The solution - provide a permanent load on the PSU main output. I achieved this by replacing the original fans with 24V ones connected directly to the 28V rail. This will then stop the transient than can destroy the PSU. The Bonus is that the fans then run all the time, so neither your PSU or PA heatsinks get hot in the first place! My PSU is totally stock, and never gives any trouble.
Sure, the Digital Board has lots of bad solder-through connections - these all need re-soldering, with a thin wire through each hole. It takes time, but once done will prevent the usual faults on this board (I never bought a Piexx board).
If your Driver Transistors fail, a simple fix is to fit 2SC1969s fed via a 3amp 7812. They have the same gain, and no other mods are required. The PA Transistors should never fail, as Kenwood used a Motorola design for the PA Board, which was rated at 300 watts output.
I have also drastically reduced the ALC Time Constant, and now have greatly increased Talkpower.
I have 250Hz filters in both the the 8.8MHz and 455kHz I.F.s, and this is a superb rig on CW. Also sounds great on SSB, as long as you get rid of the very restricted original microphone!
Overall I would rate this rig against any of the latest Transceivers in performance terms, and the big plus for me is that you can actually repair it, as it doesn't contain obsolete ICs. And the fact that it only cost me £300 makes it a real bargain! |
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| N5OP |
Rating: |
2020-10-25 | |
| An Excellent Rig, Especially When Updated |
Time Owned: more than 12 months. |
I've had my TS-930S since 1984, purchased new. It has the full compliment of filters plus the INRAD roofing filter. I have updated the power supply with the W6NL mods and replaced all the PS capacitors. I haven't needed to replace the PS with a modern switcher (the internet has various examples). It also has the PIEXX board installed, which allows computer control of almost everything but mode and filter selection. Mine also has the original ATU and it still works, though its matching range is limited. Mine has never been happy on 12 m, but it works well enough on all the other bands.
It has a fine receiver and a good transmitter. However, it does produce a fair bit of transmitted phase noise about which nothing can be done. I use mine mainly on CW but the transmit audio is very high quality, too.
The rig is reasonably easy to fix if anything is broken, though specialized parts may be hard to come by. It's also easy to align, and it will need alignment at this age. If you want a good transceiver that comes close to the rx performance of current, modern day receivers, the TS-930S with the INRAD roofing filter is tough to beat for the price.
Added 10/23/2020: I removed the original power supply board and replace dit with e Phoenix Contact switcher and power supply board from https://k6iok.com/. This removed the Achilles heel of th eradio: it's oddball power supply that's prone to failure, which will destroy the unobtainable driver transistors in the PA unit. If you have a TS-8930S, do this mod: it's well worth the investment to keep this great old radio running for a long time. It also runs much cooler with this new power supply.
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| W0RDX |
Rating: |
2019-03-30 | |
| Great Old Iron |
Time Owned: more than 12 months. |
| These radios still play as well as the newer models out there. The only con to the radio is it is analog, meaning when you change bands you likely have to manually change the mode from USB to LSB. Tuning up and down the band is a bit of main knob tweaking but no big deal. The 930 hears well and the NB actually work! They are heavy and a bitch to ship to say the least. You can get one really clean anywhere from 350-500, if you pay more you are likely being ripped off. They are not worth that in 2018-2019 now. If you have one, hang on to it. |
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| G0KMC |
Rating: |
2018-08-09 | |
| one of the greats |
Time Owned: 0 to 3 months. |
Hi
Just acquired a low mileage 7 mill s/n 930s after years of wanting one. What a wonderful easy going receiver, the best I have ever heard that didnt have tubes in it, CW is pure pleasure using the VBT and AF tune, SSB rich and smooth sound. I'm probably going to sell my 590s now.
Love the decent sized control knobs and the absence of endless menues and software ballony. Mine has 3 leg regulators instead of shunt zeners and runs cool. Mod'd it already, wired a crowbar down stream of 28 v fuse and fuse and crowbar to the 21.7 volt supply just in case. This one is a keeper for sure!
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| NY2F |
Rating: |
2018-04-17 | |
| Original Owner |
Time Owned: more than 12 months. |
| After 35 Years, Amazing. I have compared to other newer transceivers, will not mention names. HI, still impressed. Find a clean in the box and out.....You will be very Happy...Regards, Frank |
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| N6BIZ |
Rating: |
2017-02-06 | |
| AVVID |
Time Owned: more than 12 months. |
Send ur 930 to AVVID
U can thank me later old man
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Earlier 5-star review posted by N6BIZ on 2014-07-09
W3AFC WAS MY INSIRATION IN RESCUING MY 930... I HAD MINE REPAIRED AND I BY ACCIDENTI BLEW UP THE AVR BOARD... MINE IS A 4MIL SERIAL NUMBER...
I ENDED UP BUYING A SURPLUS PHONIEX CONTACT PS...
I WENT FOR BROKE!!!I GUTTED EVERYTHING THE 930 HAD FOR A PS AND I MEAN EVERYTHING... I HAD TO REPACE THE DIGITAL BOARD WITH A PIEEX BOARD TOO... I EVEN GOT RID OF THE RESISTORS IN THE FAN CAGE AND REPLACED THE 4 RESISTORS WITH THESE LITTLE VOLTAGE REGULATOR BOARDS FROM CHINA 5 FOR $6.32 SHIPPED... ADDED 2 24 V FANS RUNNING CONTINUOULY AT 17V VIA THE REG BOARDS... I SET THE VOLTAGE OUTPUT FROM THE PC AT 25.5V... THE V OUT FROM THE NEW RESISTORS TO POWER THE REST OF THE 930 AT 17V FOR THEM ALL ... THE 930 WILL RUN ALL DAY AND NIGHT AND IS COLD!!! NO HEAT!!! I LOVE IT!!! NOW WHEN I LOOK BACK AT IT, I COULD DO THIS TRANSFORMATION IN LESS THAN 2 HOURS, ITS THAT SIMPLE , THATS IF YOU HAVE THE GUTS TO DO WHAT I DO ...YOU MAY CONTACT ME N6BIZ@YAHOO.COM OR W3AFC... HES THE GENEIUS ...
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| KC6USM |
Rating: |
2017-02-05 | |
| Display error |
Time Owned: 0 to 3 months. |
I have a ts 930s I just bought on ebay. The tx/ rx
Display is 2khz off frequency on all bands. Tx
Power is 110w. Power supply is 28v,not overheating.
Usb/ ,LSB seem ok. .2uV Sen or better all bands.
Tx Mike audio Hasystem squeal. Very little audio
Output. Ant tuner works fine, TX is on and off, not
Consistent. Am is not working. Fans ok. Need help.
Want to get this masterpiece working again. Nice
Radio.... thank you... Gary Kc6usm |
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| K4GNO |
Rating: |
2015-09-19 | |
| True Classic |
Time Owned: more than 12 months. |
| I recently had my TS930S repaired and restored with the addition of the PIEXX Digital board and new power supply componants. Even after 31 years, the receiver sounds better than many I hear in today's rigs (including a much newer Kenwood that I own.). On CW it's a dream to use. The layout and ease of operation alone make it outstanding. |
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| ZL1BAK |
Rating: |
2014-11-07 | |
| Great older radio |
Time Owned: 0 to 3 months. |
| I am a big fan of Kenwood hybrids and the 930 is almost as good as my 830 to use.I like the fact that it is a decent size and has no menus to set up etc. I get good reports on my audio and the receiver is very good. I have the matching sp930 speaker and use an mc50 microphone. This combination makes a really nice home station. |
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| PA3FPV |
Rating: |
2014-09-24 | |
| Blown MRF485 drivers |
Time Owned: 0 to 3 months. |
I fixed my TS-930's PA which had its MRF485 drivers blown and their 22 ohms base resistors burned out. After that I also gutted out the original power supply ('though it was not broken apparently) and replaced it with a new Phoenix Quint 24V/10A SMPS which was supplied by Paul PA2VC, and which is similar to the one John W3AFC used.
Fortunately I did not just drop in my Eleflow MRF485 replacements to start with... Since the power supply had not been broken, nor seemed to have ever been broken, I first had to investigate what else caused the drivers to blow.
I cut out the shorted D5 zener, replaced the burned out 22 ohms base resistors with new ones and put in a pair of cheap BD135s. By then I had not changed anything to the circuitry yet and I was just curious to see what would happen when I would activate the "Send" switch. And so I did -without any drive, obviously.
The BD135s, well, the 22 ohms base resistors actually, literally burned out in front of my eyes instantly!!
While the power supply was not erroneous, the most likely reason for the drivers to burn out is that they get 28.5V (or some other too high voltage) at their bases, I figured. But everything was happening so fast, that I could not measure anything.
I decided to renew the capacitors and resistors in the feedback circuits (and put in the second pair of BD135s). I switched to "Send" again and nothing started to smoke!
I can hardly imagine that those feedback circuits can go wrong, but this is what I experienced. The old capacitors didn't show leakage on an ohmmeter; the resistors had lost their original value (but not dramatically).
Now I applied some RF drive: instantly the stuff burned out again. I suppose the problem had initially been solved by renewing the feedback circuits. The second pair of BD135s however, were "hanging in the air"; not cooled whatsoever. So maybe they now broke down for that reason. I don't know.
At this point I started to do the boring through hole fixes as described in Service Bulletin 886. You may have heard about them too. Along the way I replaced the 723 regulator by a new one and Q6, which didn't seem broken. I put in a 5.1V zener for D5. For what's it worth; in my opinion any zener in this position is worth nothing. At least it can never protect the drivers, so can anyone tell us what's the point in having a zener there!?
By this time I changed the circuitry a little in order to try some cheap FETs as drivers. I still didn't want to risk my pair of MRF485s yet. First I used a pair of IRF820s which were good up to 14MHz (100W output). Then I used a pair of IRF710s which were better above 14MHz. But the output was not satisfactory. I got about 30W on 28MHz. But at the least nothing was burning and this was the first time I actually did have true output!
With hesitation I changed back the circuitry and put in the valuable MRF485s. As expected they didn't blow without drive. I adjusted their bias for about 60mA. So after that I applied drive and.... they still did not blow! The PA now delivers 100-120W on all bands as per the manual.
The original power supply was running very hot - even on receive only. From what I read about it that's normal, but I built in the new Quint anyway. We will see what will happen in the future; so far I've made several short QSOs on the TS-930 which seems to be fixed now!
Considerations
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I am not sure for what reason the original MRF485s broke down. I just bought the TS-930 in this condition. The power supply was not broken.
So what had gone wrong?
PA0MBJ, an electronic design engineer, examined the TS-930's PA and he came about with the following I freely translated into English:
"There is something odd about that MRF485. Its datasheet states that its Vce-max is 35V so the 28.5V supply voltage seems to be acceptable. But in transformer loads the peak voltage will rise! There will be a superposition of the supply voltage PLUS the AC peak voltage. That combination is very likely to reach about 50V, which is of course by far no longer safe for the MRF485.
I don't intend to know better than Kenwood but I don't understand... To me it smells of a blunder in the design."
If he is right, all MRF485s in both the TS-930 and TS-940 are unsafe. So they will all break down sooner or later, no matter how fine the (new) power supplies is running.
Hopefully the Eleflow replacements are more robust than the original Motorola ones.
Maybe mine broke down because of a leaky feedback circuit. If they will blow again, I would first replace the feedback circuits again. But it is an unlikely failure. If everything else seems to be good too, I would consider using cheaper 2SC1969s or so and get 15V from a 78T15 regulator.
But let's hope for the better |
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