Fw: SB-104 again

[Kees & Sandy Talen]

Interesting questions you ask, Murray. The answer to this one
should be quite useful to all SB-104(A) owners.

I would be interested in what you receive offline relative to "birdies".
They are present on my unit too (seems to be a "characteristic")
and I haven't had time to locate them all ...I post results to the SB-104(A)
repair site later. There are three that I know of now which create birdies
1) having the LMO level set too high OR too low, 2) loosing ground
contact either at a screw or the grounds at the card guides on the sides
of the cards, 3) distorted signal off the HFO/Premix board.

I've installed diplexors on the "G" board to better terminate the mixers
"off frequency" to 50 ohms which should reduce unwanted signals
but no comparison between an unmodified board has been made.
Return paths tend to follow "path of least resistance" sometimes
creating a loop which radiates. Also there tend to be many unwanted
mixer products in a SB-104(A).

My SB-102 is REAL quiet (re birdies) compared to my SB-104A
(as it presently sits). And REAL sensitive ...but that's another story.

73s  Kees K5BCQ
Radio Homepage   http://www.qsl.net/k5bcq/


----- Original Message -----
From: Murray Grandy <mgrandy at TELUS.NET>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Monday, April 09, 2001 3:03 PM
Subject: SB-104 again


> Thanks again to all the peoples who responded to my question re the
infamous
> RCA Jack. I did replace the jack with a good quality BNC connector but,
> before anyone comes after me with a rusty knife, I saved the original
jack,
> wrapped it in a zip lock sackie, ( that's baggie to any Canadians listing)
> and taped it securely inside the cabinet, and as Bill would say "I did not
> have sex with that Heathkit". I can put it back to original quickern' you
> can say "rusty knife". I do have another question, although I do not wish
to
> kick over another Hornet's nest as the last question  seems to have done.
My
> SB-104A seems to have an awful lot of oscillations (I think they're called
> birdies) at various places on the dial. Seems I've heard about some mod or
> other to fix this. Does anyone know about this?
> Murray
>
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