[Collins] KWS-1 Finals

Sun, 25 Aug 2002 17:08:18 -0400

Hello Collins Experts et al...

I'm in the midst of bringing a KWS-1 back to life. I've got the power supply and most of the RF deck running pretty close to spec. However, I'm suspecting the finals are toast, and before I pop loose the $200 for new finals, I thought I'd check with the experts. Here are my symptoms:

1. All the voltages are correct, grid volts -62 for 100 ma idling plate current. Screens 350V, plate 2KV.

2. RF output is very low. It varies from 350 watts out max on 80, and decreases on higher bands. Maybe 75 watts on 20. This is with 20-40 volts of drive on the grids. I'm expecting more like 600 watts out.

3. RF output can be improved by increasing bias current to 200 ma or more.

4. With plate and screen voltage applied, I can never get any grid current to flow even at max drive. (Grid current meter indicates plenty of grid current with no plate/screen voltage in CAL mode).

5. Max power out doesn't correspond with plate current dip, in spite of checking neutralization.

Any other ideas, besides swapping in a new set of finals?

73,
Tony, K1KP