russ dworakowski wrote: > Charles, I have a 500B, that came to me as basket case. I ended up with > all new iron. Hopefully, yours was stored well, and not ina damp > location. If so, it would be good to just fire it up and let it dry out. > Its amazing how much moisture those old open transformers > soak up. When all said and done,my GK 500B, had changes in the > modulator- A higher voltage on the plate transformer- 1500v. I put neg. 5 > volts bias on the 811s. In the speech amp, I did not change anything. I > used a D104 mic and I got real good audio rpts. I also solid stated the > modulator power supply- the 816s kept flashing over,so bye bye. Also > switched to 3B28s in the RF power supply. > Have fun! Russ
I have owned my 500A for 30 years but havent used it for maybe 15. It seems to have survived basement storage with all iron intact. It already has 3B28's and i can see that the 816's will be at least an inconvenience so they might go. I have a D104 and will try it before i modify the speech amp, but eventually i want to get rid of the couplettes and try a Shure SM5B and a broadcast mic compressor left over from my years as a broadcast engineer. I am not inclined to trying to boost the modulation since i won't be in an Arbitron-driven loudness war. I do see a number of very old original small electrolytic caps in the modualtor that probably should be replaced. 73 de W3NU
