[Hallicrafters] SX 101A Challenge

[Radio Randy]

Hi gang,

Forgive me for my ignorance but, due to a "slug's pace" connection, tonight,
I am unable to look at the schematic on any of the archive sites.
Therefore...I am guessing that this receiver might have a voltage regulator
tube in the oscillator stages??? If not, disregard the rest of my message.

If there is a VR tube, I would try another of those. I lack familiarity with
the use of these devices (although I am familiar with the theory) but, would
suspect a faulty regulator as one possible cause of oscillator warble.

Just my 2 cents worth. Good luck.

Radio Randy

----- Original Message -----
From: "Rocco Lardiere" <lardiere at ix.netcom.com>
To: <hallicrafters at mailman.qth.net>
Sent: Thursday, September 12, 2002 10:46 PM
Subject: [Hallicrafters] SX 101A Challenge


> To the Hallicrafters Experts:
>
> OK - I am stumped.  My SX 101A local osciallator is warbling slightly,
> and I can't stabilize it.  This is not the usual temperture drift.  This
> is a slight delta frequency, continuous, perhaps only back and forth a
> few cycles, but it is constant from turn on to whenever.  It just sounds
> awful on CW.  It is more pronounced at higher frequency bands.  The
> problem is in the 1st conversion oscillator - I can hear it clearly when
> I couple my test receiver to the tube and listen to it directly.
>
> I have rebuilt and resoldered the components around V3, the 12By7A, and
> it is less prone to vibration now.  This problem is not related to
> vibration or turn on temperature changes.  The B+ and bias to the
> cathode look clean and stable.  The warble is not a steady beat note -
> it is just back and forth at a few hertz, but not at a stable low
> frequency.
>
> I have tried tugging on every freq component, including the main
> variable cap.  I resoldered everything in sight.  Everything looks
> solid.
>
> This is a really beautiful 101A - very, very clean, so I want to save
> it.  I suspect the receiver is like new because this problem has been
> there from very early in its life.
>
> Any hints?
>
> Rocco Lardiere N6KN
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