Kenwood TS-820S Modulation Issues

[@larrychapman6130]

Thanks Tim, I have an 820 with the same issue. Thanks for all of the troubleshooting.

[@iw0hex]

Great job Tim. Thanks, I have an TS-820 too. 73s !

[@timtimeprojects3576]

Thanks Pasquale. I can't seem to get away from these old Kenwoods. I have a TS-940 as well I want to show some repairs and findings.

[@kevinerickson1618]

Great video. What was the outcome?

[@timtimeprojects3576]

Thanks Kevin. It seemed to be that the factory transistors were not sufficient. I was hoping for a faulty or failed transistor, but they tested ok. The bulletin said to just replace them. Maybe I will compare the gain to new transistors and post the results. If I can find where I put them for safe keeping.

[@almartorella8008]

I don’t know how to get in touch with you can you do a repair on my Kenwood 820 I just bought it on eBay it for some reason my meter doesn’t work and I don’t know if it’s transmitted because I can’t make any contacts I’m relatively new to him very new to HF can you help me

[@timtimeprojects3576]

Hi Al and welcome to the hobby. I don't do much work on the side as my real job keeps me too busy. And mailing one of these boat anchors is expensive and bad for it's health. That meter does many things. See if it works on vc - should read about 28. Then check ic - should be about 10 in cw while sending on full power. Check the swr with an external meter just to see if you get any output in cw, am or fm. In Alc the meter should move around when you talk on cw with mic and power set to full. If you have a poor antenna match, the power will drop way down. Find the manuals and read up on the operation of that radio. It has a lot of functions to play around with. They are great radios but like an old car - not always real dependable. Don't be afraid to experiment a bit with that radio. Most of the problems with be connectors or solder joints. Try not to adjust anything unless your pretty sure that's the problem. The radio should still work without an alignment unless somebody else did an alignment. Once you get it up and running and know the radio then worry about alignments. That radio is a monster to align.

[@timtimeprojects3576]

Sorry Al. I didn't look at which radio you were talking about because I just posted a new 940 video. I will take a look at my 820 notes and give you a few things to try.

[@timtimeprojects3576]

Al, First make sure that there is a jumper plug in the back at the radio in the Ext VFO Jack. It won't work without that. You have to check the manual for the tuning procedure. That radio MUST be tuned every time you change the frequency. First test of the meter is to put it switch to IP and send in USB or LSB. The meter should go to about 60 ma. Most of the other things I advised about the 940 hold true for this as well. But be carefull, high voltages in these old tube radios. Follow the tuning procedure in the manual before trying any more transmitting. Its only about 4 steps and can be done in just a few seconds.

[@almartorella8008]

My meter only works when it’s on COMP any other time the meter does not work

[@timtimeprojects3576]

I would take a look at the connections at the Meter Switch and where the wires go into the Final Unit through an inductor. Also look at Relay RL-3 and make sure it’s working. I think RL-3 is located on the Relay Board.