Wonder if someone can point me in the right direction. I have never owned 
Collins B4, and purchased a 75S3 on Ebay. Out of the box it was very 
insensitive. It had a few problems, mainly with the power supply, which I 
fixed, including new filter caps, replacing all of the paper and 
electrolytics throughout the radio, etc. I also completely retubed it.

It is still quite insensitive, particularly on 20 M and up. I also notice 
that I have to turn up the audio gain full blast to get adequate volume ( I 
am using an 8 ohm spkr). Under this condition i get a lot of hiss.

The AGC line seems OK, and S meter works fine. All voltages were measured 
throughout the radio as per the book and seem to be within specs.

I did some basic tweaking of the alignment, and no joy yet, although I have 
not done a full alignment as per the book.

Another lesser problem is when I switch in the tunable BFO, I get a fairly 
loud hum (no hum on CW, AM, or both regular sideband positions)

1. Should I be able to get adequte volume with an 8 ohm spkr?
2. Anywhere u can point me to re the sensitivity issue. I have worked on a 
lot of radios in the past and this one has me stumped.
3. Anyone had this problem with the BFO?
4. The preselect seems to have a fairly sharp peak compared to my Heath 
radios, although it is not totally goofy. It seems to need a repeak within 
one band segment of 40 Meters. Is this normal? (although I guess given the 
lousy overall sensitivity, it probably needs all the peaking it can get!)

PS - Bought it from "you know who"

73 and thanks to all


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