[Hallicrafters] SX-115 anomaly

[Al Parker]

Hi Jim, et al,
	I hoped Todd, or somebody, would have a possible solution for you, but 
guess I had to hunt up my manual to follow my thought.
	I think you're right abt the 3rd mixer being the problem.  Look at pg 
13 in the manual, maybe adjusting T8 (upper and lower slugs as 
appropriate) to help the oscillator to start running.  I thought there 
would be an adjustment, either a slug or trimmer, just needed to RTFM.
	Todd's suggestion is also a good one, clean things up.
	By chance, would it start working if you just switched sidebands?  You 
could swap in a new 12AT7, that might have one weak section.
	Sorry it's taken us so long to break out of the weekend doldrums.
73,

Al, W8UT
www.boatanchors.org
www.hammarlund.info

"There is nothing -- absolutely nothing -- half so much
worth doing as simply messing about in boats"
Ratty, to Mole

On 6/4/2012 1:30 PM, Todd, KA1KAQ wrote:
> On Sat, Jun 2, 2012 at 10:35 PM, Jim Marshall<jmarshall1945 at yahoo.com>wrote:
>
>>
>> One thing that is a very slight problem that continues to bother me, but
>> not so much to really tear in to it, is that when I first power the rig up,
>> the actual receive frequency is about 50 khz higher than displayed. This
>> would indicate to me that the 3rd mixer or ssb crystal oscillator is not
>> firing. The fix is to simply change the band switch up or down then back to
>> the desired band, and the radio works fine. It always does this on power
>> up, and stays working after I do the band switch thing....
>>
>
> Sounds like the similar problems I've had with a 75A-4, caused by some bad
> mica caps. Could also be an aging crystal that needs a little kick to get
> it oscillating causing the problem. Had an SX-101 that exhibited this
> issue, tweaking a slug made it oscillate but was a PITA to do each time.
>
> Start by cleaning all connections (sockets, pins, etc) for crystals and
> switches. Then move on the checking components. Considering it's roughly a
> 50 yr old radio, it's probably due for some maintenance.
>
> Good luck with it -
>
> ~ Todd,  KA1KAQ/4
> ______________________________________________________________