[R-390] Open Z-503 AGC IF Transformer

[ToddRoberts2001 at aol.com]

If anyone is interested here is a recap of the measurements I took of the 
tuned circuit Z-503 inductor coil L514. I measured the inductance of the coil as 
1.385mH. I also had a chance to measure the Q of the Z-503 coil L514 and I was 
surprised to find it measured a very low Q of only about 30-40 Q at 455KHz on 
the Heathkit Q-meter. I have a bag of small 1.2mH molded inductors I picked 
up a while ago from Hosfelt Electronics and measured one and its Q was about 60 
at 455KHz so it looks like just about any small commercial inductor would 
work fine to get Z-503 working again. I think those inductors only cost me about 
20 cents each. I found it took about 85pF to resonate the 1.2mH inductor  at 
455KHz, so a typical small Mica cap would work well across the inductor to get 
Z-503 working again. Best to use something like a Heathkit Q-meter to 
determine how much capacity is needed to resonate the new coil at 455KHz due to the 
unknown distributed capacity of different inductors. If someone ever needed help 
with a burned out Z-503 I can mix and match small inductors with a small cap 
to resonate at 455KHz. 73 Todd WD4NGG