Wednesday, Nov. 4, 2020
I took the case off my new Kenwood TS-520SE and purchased a can of DeOxit contact cleaner. I was watching YouTube videos of common TS-520x problems, and dirty contacts seem to be common on these rigs.
My 520SE exhibited dirty contacts on most of the controls, so once I had it apart and did a quick inspection, I went thru and cleaned all the front panel switches, pots and controls.
The cleaning did a great job; the attenuator button seemed inoperative, but once cleaned, it functions properly. Same with the RIT switch. I didn’t realize until I saw the videos of just how many sections there are to the bandswitch on the TS-520. I cleaned all the sections and even lubricated the Drive control, which uses chains to gang together variable caps.
Unfortunately, the thorough contact cleaning did not bring back my transmit signal, though I did some thorough testing and found that the rig’s best output is on 15 meters, with about 15 watts out.
The interior of the rig looks excellent; one of the main filter caps shows a little “domeing” and probably should be replaced. The other one looks fine.
At this point, I’m going to test the driver tube and the finals to see how they test. The final tubes look original and have 40 years of dust and grime on them. I’m hoping the tubes are the problem. I went over the finals section of the rig, and there’s no components that appear to have gotten hot or burned. Everything in the finals cage looks fine, and the tube filaments are working, as is the high voltage.
CW FILTER ARRIVES. My new-to-me Heathkit CW filter arrived in today’s mail. I haven’t had a chance to install it yet, and will probably wait until I get the finals checked in the 520 and I can button it back up with the covers.
It was ironic tonight on my CW traffic net … with the 520 torn apart at the operating desk in Studio C, I checked in from my main shack with my FT-2000. I don’t know what all the CW activity was about, but there was a fairly loud station within 150 Hertz of the net frequency. The NCS moved about that far on the other side of the signal, though I didn’t realize it at first … I couldn’t narrow the CW bandwidth enough to get rid of the extra signal, the signal I was tuning out was the NCS. I retuned and got on frequency Q5.
While I have my SB-102 apart to add the CW filter, I’m going to take time to clean all the switches and contacts; the seller I bought the SB-102 from said it worked fine, just suffered from dirty contacts. On the Heathkit, the mode switch is I need to clean most., along with the volume and RF gain pots.
THURSDAY, NOV. 5, 2020. I broke out my tube testers earlier today to try and check out the driver and final tubes in my TS-520SE.
Now the truth is that I’m not sure of how well EITHER tube tester works; one I bought off eBay, the other is one my brother was given by a friend of his. Both are mutual conductance testers, so they’re quality units.
The 6146s both tested good on both testers. The 12BY7 driver, not so much. On my Hickok 707, the driver tube tested very low, even intermittent. I’m not sure if the issue was the tube pins, but I believe it was the tube socket. I had to jiggle the tube around to get the tube to work in the Hickok. The other tube tester, the tube tested better, and without any sign of being intermittent.
Just for the process of elimination, I have decided to order a new driver tube and finals. I don’t really think the finals are bad, but the 6146 is such a common tube, I think I’ll find a use for them in one rig or another.
I have reinspected the finals cage, top and bottom, and still can’t find any parts that look overheated, abused, or missing the magic smoke. I think I’m going to have to get in with a meter and make some voltage checks.
I still need to install my CW filter in my SB-102. Right now I can’t operate from Studio C because I have the TS-520SE spread apart at the operating position. I need another work space up there.
I would still like to repaint the case if I can get paint to match. All good things in time.
73 es CUL … de KY4Z …. SK … SK …. (dit dit) ….