[Hallicrafters] SX115 Mode switch problem on LSG

[lardiere at ix.netcom.com]

Mark,

Thanks for the hints.  I have a pristine SX-101A that has a "wandering" VFO.  I think the problem is in the soldering of the main tuning cap, which is difficult to access.  One of these days, I will go in there again and try to fix that.  When I do, I will take your advice on the caps to heart.  My sense is that the 101A has great potential - it is a very late production model, concurrent with the 115.  

Sorry to have missed you in the CX.  My Colorado station is not very capable in the antenna dept.  Wish I could have operated from here in California, but my Colorado/LA work schedule did not permit that.  

73,

Rocco N6KN

-----Original Message-----
>From: Mark K3MSB <mark.k3msb at gmail.com>
>Sent: Oct 20, 2007 8:12 AM
>To: lardiere at ix.netcom.com
>Cc: jeremy-ca <km1h at jeremy.mv.com>, Mike Anderson <Mike.Anderson at motion-ind.com>, hallicrafters at mailman.qth.net, rrkrr <rrkrr at comcast.net>
>Subject: Re: [Hallicrafters] SX115 Mode switch problem on LSG
>
>Had / have a problem(s)  -- how's that for grammar -- with my SX-101A
>over the years.
>
>Picked it up in 99,  and would loose the audio in one of the sideband
>positions.   I swapped the crystals with those in my SX-111 and the
>101A worked fine, as did the 111.
>
>The problem cropped up last year again in the 101A.   I've completely
>recapped my 101A except for the selectivity switch which I'll get to
>over the Christmas holidays.  Now the radio works in the "troubled"
>sideband position after warmup,  but typically not during.
>
>This may be cured with a complete alignment (but I want to wait until
>I have the selectivity caps replaced).    IIRC,  the alignment for the
>stage the crystals are in requires you to select the mid point of the
>gentle slope off peak voltage (the other side is a sharper slope).
>What may be happening is that the radio is so far down the slope that
>it's not oscillating correctly,  but get's back into alignment enough
>after warmup.     Silver migration in the SM caps in the transformers
>may also be contributing so I've been told;  I've not replaced them
>yet in my 101A as getting the subchassis off does not seem like fun.
>
>BTW,  recapping the 101A really perked the radio up;  it was a great
>receiver on 10M AM as we were coming off the solar cycle peak and that
>was before recapping.   Now I typically run the radio with the RF Gain
>not even midway.
>
>BTW #2 -- almost every black beauty cap in the 101A failed it's
>voltage test.  EVERY 600 V BB failed at 50% voltage;  the worst
>crapped out at 100V.   And the radio worked great in that condition!!!
>  If I'd know the BB caps were that bad,  I'd have done the
>replacement years ago.   But since the radio was working nicely,  I
>wasn't worried about it.   I should've been.
>
>OK, sorry to be long winded and wander down a few rabbit trails..........
>
>73 Mark K3MSB
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