Well.. I spent a small fortune on ham radio in the last two months or so. One purchase is a new TS-590S and the other... well...
I bought a used TL-922A that was in very good cosmetic shape about three weeks ago. Didn't have time to fire it up until today. It has new RF Parts 3-500ZG tubes, AG6K suppressors... and well it had a 160m "improvement" mod done to it. I paid good money for it. Enough that I'm almost embarrassed to say, depending on how this all turns out. Cosmetically 9/10.. Good power out for the 3/4 hour or so.
Now I hope it still has a functional HV supply. I am wondering if I have another SB-200 that I finally got everything shaken out of right before buying the TL-922. (Took 9 years.. but then again, it was a cheap amp to start off with...) It was putting out 1000-1200W on all bands I tried (as it is supposed to) with about 85W of drive.... 80m/75m, 40m, 20m... 15m *POP*
eek...crapola.. that was a lot of $$ that went up in smoke...
Here is the culprit:
Okay.. the guy doing the mod did nice clean work.. HOWEVER.. one cannot bypass (the glitch resistor too! I hope the HV is ok...!!!) the plate supply, which is 3.1 KV (SSB) on the TL-922 with a 0.005 uF 3 KV disc!!! (The other end was attached to the interlock mounting screw for ground with longer leads than I would have liked as well.) I suppose if that is a major improvement on 160m and 80m that I can add about 5000 pF with another 7 KV+ DOORKNOB cap.. but this addition made the amp pop and go boom within about 45 minutes of when I first turned it on.
Unfortunately that cap is now a 55 ohm resistor and it did take out one of the two "Bussman" FNM-15 time delay fuses. I'm keeping my fingers crossed that the supply can take it. The interlock is there also, but it's still a frightening proposition when something like this happens!
Of other interest, and I am going to e-mail Rich Measures... it appears that the resistors in the suppressor kit (which are bypassed with the nichrome wire and getting a little discolored. I don't know if that is because of the cap venting out (it is possible) or there is something else wrong.
See the suppressors look like they are installed correctly (according to what I've read on the web), however the ones that are bypassed with the nichrome coils seem a little discolored at the ends. I am gong to e-mail the designer of these suppressors and see what he has to say about that.
Anyway.. it's starting to be that sort of weekend. The TS-590S seems pretty impressive and I am looking forward to running it with this amp.. but maybe I'll be out over $1K (I said it) and will have to use the ugly SB-200 with it instead.
Sigh..
From a physical check of the unit, it all else seems good (no smoked parts).. so once I can get over to the local Grainger store to get this oddball fuse, I am *hoping* I can fire it back up.
Anyone else want to comment on the extra 0.005 uF... should I start digging for a doorknob to add to the amp, or was it a stupid "improvement"?
Needless to say.. the moral of this story is do not parallel or replace a doorknob with a disc! Do not put a 3 kV disc in a 3.1 KV DC circuit with over 100V of AC injected on it. sigh...
