Kenwood TS 820 problem

[KG4KRI]

I have a TS 820 with a puzzling problem. I have full CW power output on 160, 80, 40, and 15 meters, but only about 20 watts out on 20 and 10 meters. I have aligned the coil pack, and I test my power output into a nonreactive dummy load. I have not checked neutralization. I believe that the driver and power tubes are original equipment, but I don't know if tubes go "soft" only on one or two bands. Any hints or ideas will be appreciated.
                               73,   KG4KRI

[W9GB]

From your report, I am assuming that you have a good 50 ohm dummy load (Heath Cantenna, Drake/Vectronic/MFJ 100 - 150 dummy load).

You can always test your tunes on a reliable tube tester.  Neutralization should always be perfromed when you "change" tubes in this transceiver (instructions in your user manual - abailable from Kenwood or one of the manual services).

"I have aligned the coil pack"

I don't understand this statement

Without proper test equipment "twiddling" with adjustable coils and capacitors in LC circuits or the filter section is a fools game.

There could be a component failure or value change that is causing you symptoms in the 20 and 10 meter sections of the transmit chain.

Call your local amateur store's service department or if you don't have a local store, drop an e-mail to Cliff at AVVID  Clif@avvid.com

http://www.avvid.com/

Reasonable rates.  Can get you back on the air with full power on 20 and 10 meters (and re-align the receiver).

Greg
w9gb

[RobertKoernerExAE7G]

When tubes start going soft, it shows up on the highest frequencies first, which would be ten meters, followed by 15 meters.

[KG4KRI]

Thanks for your reply, Greg. I have a service manual, but the only procedure that I have performed is the coil pack adjustment, i.e. peaking the drive, mix and antenna coils in the center of each band. Hopefully, the full checkup should reveal the problem. A failed or out of tolerance component is a real possibility with this rig, as its previous owner used it heavily on 10 and 20 meters. I am also glad to know the failure pattern of "soft" output tubes.

                             73,       KG4KRI

[K0XU]

You also might want to try using a good contact cleaner on all the levels of the bandswitch. Something like Caig's Deoxit (hope I spelled all that right)