N3VC's SB-200

before & during work

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It was owned by a heavy smoker by the looks.

   Done, with old tubes installed for checkout.  I have done some cleaning, but more will be done.
   I installed Ken Simpson's suggested mods, back-to-back diodes on the meter, and a diode across the antenna coil. 

With my shack wattmeter, the old tubes (both OK) will get over 500w output on all bands, driven with approx. 100w from my Ten-Tec Omni V.  (The wattmeter used is 500w f.s.)

done1r.jpg (208968 bytes)  done3r.jpg (272474 bytes) done4r.jpg (200155 bytes) done2r.jpg (107650 bytes)

the above pix are after mods, before cleaning, show heavy nicotine stains, and it smells when hot.
compare with the ones below, should look cleaner.  I only did light damp cloth cleaning on the front panel, the paint & lettering will come off if scrubbed.  

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I will install old, then new, tubes and put the "big" wattmeter on it to compare readings.

Here's what I'm getting for power readings:

Freq.     Ip, ma.   Pwr out, watts    Load ctrl setting
3780      500        740                    3
7280      500        840                    4
14280    500        900                    5
21280    500        900                    4-1/2
28280    400        450                    5-1/2

Not very efficient on 10, that load setting gives the max. power out  The input ckt tuning has little, if any, effect on 15 & 10m.  Input SWR is about 2:1 on those bands, so it's not a mismatch.