[Hallicrafters] SX-71 Bandswitch problem

[Al Parker]

Hi Phil,
    I had an SX-71 a while back, got it real cheap, discovered that most of
the antenna coils were burned up/shorted/open, I don't remember exactly
what.  I ended up removing them and repairing/rewinding as needed.  It must
have gotten xmtd into, or lightning, or??   I fussed with it for many mo.s,
off & on (mostly off), couldn't get the band that covered 40m to track
properly.  Could set for good sensitivity at one end or middle, but
wouldn't track.  Couldn't find anything that was disconnected on that band,
etc.  Finally got disgusted, sold it cheap, with that problem properly
revealed to the buyer.
    Hope this isn't your problem, but your experience of jumping to the 2nd
stage sounded familiar.
73,
Al, W8UT
New Bern, NC
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----- Original Message -----
From: "Phil Atchley" <ko6bb at elite.net>
> Then, I noticed that connecting and disconnecting the antenna didn't help
> any. So, connected it to the grid of the RF amplifier (actually the
tuning
> capacitor stator).  Wow, reception GREATLY improved!  This problem was
there
> when I did a preliminary checkout before starting work on the set, so
it's
> not a problem I created.
>
> Further troubleshooting indicates that the primary side of the RF coils
are
> all shorted to ground, this even when the back Panel jumper from A2 to
> ground is lifted.  When that jumper is removed the inputs should "float"
and
> have no ground.  Examination of the circuit shows no shorted wires to
ground
> that I can find.