Technical Questions & Answers
For Kenwood Amateur Transceivers TS-520, TS-520S, TS-820, TS-820S, TS-530S, TS-830S, and more!
From the K4EAA Ham Radio Mailbag

Over the years I have received and answered many thousands of technical questions from Ham Radio Operators.  At this juncture, I suspect I have answered every Kenwood question that is possible to ask at least once - And several, many, many times.   While it takes a fair amount of time to add to the FAQ, with pictures and diagrams and the like, the email questions can be copied and pasted reasonably quickly.  That is what I have done here.

I will be adding to these as time permits, as I have over four years worth, after all!   You can either read through the emails page-by-page (like a novel!), or search the site for keywords which will lead you directly to your area of interest.   ENJOY!   Ken, K4EAA

Tech Question Page Navigation  Previous   1   2   3   4   5   6   7   8   9   10   11   Next

I did what you said regarding the cleaning of the vfo with deoxit. The VFO no longer drops out.

I'm still having a problem with the VFO in that it drifts, just like it might be a "dial creep" problem but it's not. I did the deoxit trick again today and had it on it's side (left side) and turned it back on and it was super stable. I thought it just needed another shot of the "good stuff". But, when I turned it to sit in the normal operating position, the instability returned. So, I turned it back on it's side and walla, it is stable. I've tried tapping/touching everything I can to see if I can replicate the problem when it's on it's side. No can find. Might actually be inside the VFO compartment and I'm not ready to tackle that at this time. I thought I'd pick your brain and see if you've ever had this problem and if so, I hope there is an easy fix. I guess I can run it on it's side but I get a crook in my neck every time I go to read the dial, hi.

Thanks for the earlier advice as that did the trick. Any other tricks in you bag Ken??

Thanks very much and best 73.


Hi Paul;

I've found a few problems that cause instability in the VFOs. Sometimes it's a part, but most times it either a mechanical problem or a dirty/contaminated PC board, surprisingly. Yours sounds mechanical. I take them apart, resolder every terminal I can get to, clean the PC Board with lacquer thinner, and tighten all screws. It's amazing how often that quiets it right down.

Good Luck,
Best 73's,

Hello Ken,
I have a TS-830-S with Bandswitch problems on 10M as you described. However, I cleaned the switch, and that seemed to cure the problems for a short period of time. But I have to push-pull, rotate a little left-right the bandswitch
Now, I also have the same problem on 15 and 20M.
Question: How would you determine whether to remove the sw assemblies and do the major repairs shown in your "repair pictures?" Or just use that different coupler you mention in the writeup? I''d Like to ship it to you for an overhaul in the fall.

Tnx es 73


Hi Ed;

Contact cleaners are not what they used to be - They "sort of" work these days. Eventually, with persistence, cleaning the contacts will fix the problem.

Consider investing in the somewhat overpriced DeOxit kit from Radio Shack at $15. It comes with two tiny spray cans, one for cleaner, and the other for lube. The EPA has banned most everything that actually works, but this Caig stuff still offers some performance.

The disassembly of the bandswitch is a last resort, not usually needed with contact performance such as you describe. Some 25 year-old contact cleaner would have fixed it on the first pass . . .

Hope this helps,
Best 73's,

Hi Ken,
I have a question that I hope you can answer.
I am trying to align a TS-820S I have here on the bench. I am trying to get the USB and LSB audio to sound close to the same.
Right now they are very different with USB sounding pretty pinched.
On page 45 in the Service manual, I was starting to perform the Carrier unit adjustment (starting at step 2), but it says to adjust T1 on CAR-1 to 50mv... Shouldn't that be 500mv? But then below in step 2, it says to adjust T1 on Car-1 again. I think they mean T1 on Car-2 in step 2... what are your thoughts?
Again, I think it should be 500mv not 50mv.

Hope all is well.

Hi Gordon;

Yes, they have a dandy misprint there - It should be 500mv. It does not work well at all at 50mv!

USB and LSB will always sound a "little" different because the filter slopes are not symmetrical. They should be pretty close, however. I usually adjust the carrier trimmers for equal low frequency response - i.e. a corner frequency of 50 or 100Hz, or whatever you prefer to sound like . . . 50 Hz at the low end makes a big difference, but isn't noticeable at the high end. Just tuning through the calibrator with your hand on an alignment tool can get you very close. Just don't go past zero-beat.

Hope this helps,
73's, Ken

Hi Ken,

I am building the Monoband Yagi that you wrote about many years ago. I was wondering what special requirements there are for the Balun. The Y1-4K from Radioworks appears now to be a Y1-5K and is almost $60. I am wondering if there is another model that might do the job for a few less dollars.

Thanks for any input.


Hi Dale;

Nice to hear from another Yagi builder! The balun should be 1:1 and be able to handle whatever power you are going to use. You could wind one yourself on an Amidon (or similar) core for a few dollars. Just Google "homebrew 1:1 balun" and you'll see lots of designs. I probably used the one I specified because it was relatively low cost back then - It must be 1:1 because tuning the antenna for 50 Ohms is where all the gain occurs - Some builders second guessed my computer analysis and used 2:1 baluns and tuned THAT for 50 Ohms. It doesn't work nearly as well done that way . . . 8^)

Let me know how it works out, and be sure to write if any questions arise - I'll be more than happy to help out.

Best 73's,


The DG-5 cable set mentions it comes with a 12v power cable. Is this for operation of the 520S with DS-1A installed?

Hi Ron;

No, it fits the standard TS-520S. If you look on the back, you'll see a two-pin jack on the upper right (as viewed from the back). That is the source of 12V for the DG-5. The TS-520S came standard with that jack, while the TS-520 required the DK-5 kit that added that 12V jack as well as the 3 outputs (HET, CAR, VFO) that the 520S also came standard with. The DS-1A has nothing to do with the DG-5 in other words. Your 520S is ready to go!

I hope this helps, Best 73's,

Hi Ken!

I have search for a replacement for 3SK41 (L) mixer fet for my old Kenwood TS-820S tranceiver. The original fets seem to be hard to find or very expensive. Are you able to name any suitable european FET for replacement? I donīt care about different package or pin configuration.

I guess the TX mixer is out of order, because TX output is less than 10 watts even the tubes are replaced. I have measured 0.03 V before mixer and 1.1 V after mixer (service manual says it should be 1.4 V). Do you have any reason for frequncy drifting (a few hundreds Hertzs occanionally)?

73 Kari

Hello Kari;

A suitable replacement for most any of the dual-gate MOSFETs is the NTE222. They should be readily available across the pond. It sounds like it might be something else, however. Have you done an alignment of the TX chain? Just follow the level diagram and tune every coil and transformer in the TX diagram for maximum. There is an alignment step in the manual that says to adjust T1 on the Carrier unit for 50mv out - That is an error, it should read "500mv out."

Drifting can be caused by the VFO - I've been able to stabilize the 820 VFO by (1) Cleaning the PCB with a solvent like lacquer thinner (2) Cleaning the air variable wiper with contact cleaner and lubing it (3) Tightening everything mechanical in the VFO (4) Resoldering connections in the VFO. An 820 can be quite stable.

Hope this helps,
Best 73's,

Dear Ken

I have a boat anchor that is giving me fits. TS-820S

Intermittent drop in Receive gain if I PTT or flip send switch, curable by turning off power and re powering. I have checked all relay contacts of both T/R relays. The problem can also be brought on by tapping the third from the front band switch. However the problem does not appear to be in the band switch,

Any hints on where to look would be appreciated.

Hi Paul;

It's usually the relay on the relay unit board - If you haven't burnished, lubed, and adjusted the contacts, you should do so. The bandswitch is another possibility, but it's usually the relay. I clean about one a week and it almost always solves the problem you describe.

Hope this helps,
Best 73's,


First off, I found your web page awesome. Thank-you for doing such a
superb job.

I have a home at the Villages in central FL but don't live there full time
yet. Hopefully next year. I hope your close to there.

I would love to be able to repair this rig myself for the learning
experience but am at a point where I can go no further without help. I
will gladly pay your hourly rate for assistance. If that doesn't work, I
would like to send the rig down. I only have $250.00 invested in the rig
so repairing it here is obviously the 1st option.

Received rig and put it on a dummy load.

Powered it up and all appeared normal.

Checked bias (60 ma) and it was OK.

Went through tune up procedure and it appeared to tune properly on 80 meters.

Rig would hesitate about 20 to 25 seconds after switching from send to
receive before it would actually receive.

I removed the TX/RX relay located on the bottom of rig and cleaned
contacts with d-ox-ide spray cleaner and a strip of business card and
dried with pressurized air.

Replaced relay and delay symptons still persisted.

Removed the top side relay by moving the board above it to gain access.

Cleaned with same method as above and replaced. However, I could not
replace the spring clip that was over the relay.

Re-positioned the board above it and tightned the four screws.

Powered rig and meter pegged. It did this in all four meter positions.

Moved the board again and removed the relay again and checked for any
crimped wires under the board. Found none.

Repowered rig with relay removed and board loose. Meter pegged as before.

Replaced relay carefully again and re-positioned board. Same problem.

I am still at a loss for what was causing the delay from tx to rx but now
I have encountered this meter pegging symptom when switching on the AC

Any suggestions? If not, how can I make arrangments to ship for repair and
alignment. What is your typical lead time?

Thanks for taking the time to read this e-mail from a desperate
technically challenged Ham who wants to learn but has no local help.

Best Regards,

Hi Jim;

Thanks for the nice compliment on my web pages - Always glad to hear they are of assistance. Today must be relay day - This is the third question about that relay that I have answered.

I still suspect the relay - The one near (under) the calibrator board. Sometimes the spring contacts are not breaking, or perhaps not touching when the relay is energized. I frequently have to adjust the contacts with that split tool I show on my parts page so the contacts positively engage in both positions. It sounds as though your cleaning (properly done I might add) may have exacerbated the problem, slightly bending a contact one way or the other.

Take a close look at the contacts as you energize the relay with a 12V source of some sort, and see if you can detect deflection on all the contacts as you alternately energize and release the coil. I'll bet there is at least one that is marginal.

Let me know what you find,
Best 73's,


The TS-830S I have belongs to the Islamorada Village Fire Station ECO, for which I am one of the communications operators. It worked fine for the past two years. In checking it out last week the output has dropped to about 10W (Ten Watts) for no known reason. Inspecting the band switch drive coupling, it is cracked, but I don't think this is the cause of the low output. I replaced the 12BY7 Driver and the outout did not change. The output was measured with a Bird 43 meter into the dummy load in my MFJ-949C Tuner.

Any suggestions as to how I can find and possibly repair the problem would be appreciated since Hurricane season is approaching. I can replace the coupling, not a real problem. I have an EE degree and am skilled at troubleshooting and repair of hybrid electronic equipment, but I don't know exactly where to start. Yes I did check the Screen Grid switch. This unit is the HF Transceiver for the EOC, but I can use my personal rig if necessary.

Thank you for your attention to this matter



Hi John;

Use the panel meter to check the HV - It should be over 800V at that output level. If it's about 400V, it's no doubt one of the HV caps, for which I have a repair kit. If the HV is OK, you'll have to open the rig and check the final screen voltage and associated resistors. Check that the cathode resistors are still at 5 Ohms as well.

The final cage doesn't have too many parts, so it should be simple to track down. Let me know what you find.
Best 73's,


Thanks for the prompt reply. I had checked the cathode resistors and they read 4.85 ohms on my Simpson 260. The Plate choke appears to be in good condition, still a bright copper color, no signs of overloading.

The problem seems to be in the HV supply. In the Tune mode, with zero carrier input the HV reads 600v as read on the panel meter. Turning up the carrier to max the HV drops to 150 volts. Possibly both of the HV Caps need to be replaced. Is there any way of being certain that the Caps are the culprits?

Again thanks for your prompt reply.



Note: It's almost ALWAYS the HV caps!

Tech Question Page Navigation  Previous   1   2   3   4   5   6   7   8   9   10   11   Next
Check out Kenwood Ham Radio Topics on all K4EAA pages!

home About Hybrid Models Steps to Restoration Repair Examples Service Rates Equipment Sales
Some Additional K4EAA Site Links

spammer killer
Please Note:  The above address is a GIF image, to foil spammer robots. 
You will have to type that address into your email client.  Thanks for your understanding, Ken

All Photos and content copyright 2005, K4EAA, Ken Kemski.

Web Counter

Cash Advance Loan