[Collins] 51J4 audio improvements??

[kwylow zinjanthropus]

Paul:
I suspect that the 51J series were pretty much tight audio boxes. In the past, I have had a few R-388's and a 51J4 and they were all characterized by thin sounding audio. Collins built their receivers with communications and selectivity rather than audio quality performance. There was a modification in ER regarding mods to the 75A4. You may want to check that mod to see if it will work on the J4. Good luck! Cal, N6KYR
 Paul <pwende@arrow.com> wrote:Hi Group,

I am the proud new owner of a very nice 51J4 with 1.4, 3 and 6KC filters
installed. The rig is all original and in very good shape (for it's age). I
went through it last night and cleaned all switches and contacts and it is
now working much better.

I am comparing this radio's audio to my Racal 6790 and yes, it is 40 years
older than the Racal, but I was expecting a little nicer audio from it. It
may just be the nature of the 6KC filter as well. I am going to do an
alignment on it over the holidays but I have a few questions.

How good can the audio from this radio be? I have use GPR-90 and R-390 and
find they were much more musical. This one may just need a good alignment
too. Can I pull out a mechanical filter and just feed in to out with a .01uF
cap? The xstal filter may be enough for hi fi listening.

Any other improvements I could make to the audio quality? BTW, I will be
trying to take the audio from the diode load to bypass the final audio
stages as well.

Look forward to your replies.

Merry Christmas!

Paul

Sponsored by the Collins Radio Association
http://www.collinsra.com


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