[Hallicrafters] SX-111 Calibration?

[Richard Knoppow]

----- Original Message ----- 
From: "Bob Macklin" <macklinbob at msn.com>
To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>; 
"Halicrafters" <Hallicrafters at mailman.qth.net>
Sent: Friday, July 13, 2012 10:40 AM
Subject: Re: [Hallicrafters] SX-111 Calibration?


> Thanks,
>
> I am thinking of centering the Dial Reset then adjusting 
> the LO to the proper end point.
>
> My initial tests showed the LO would start OK when the 
> unit was turned on. But would quit when the band was 
> changed.
>
> Working inside the LO section of this thing is extremely 
> difficult for me.
>
> I'll know more later today.
>
> Bob Macklin
> K5MYJ
> Seattle, Wa.
> "Real Radios Glow In The Dark"

     I think you are doing exactly the right thing. I assume 
you have the handbook.  There are two at BAMA one for the 
MkI, I don't know how much difference there is.  I would do 
a complete RF alignment.  If you have the necessary 
generator check the IF also but its much less likely to have 
drifted off. The adjustments will allow you to set both high 
and low band ends. Center the pointer before doing the 
alignment and, if its easy to move, lock it with a bit of 
tape. Also, the alignment instuctions want you to check what 
they call indexing, that is simply making sure that the 
pointer is at the low end of all the scales with the tuning 
capacitor closed all the way.  If its off it will throw off 
the other adjustments. This is a mechanical adjustment and 
not likely to change. Once adjusted at the frequencies 
specified the dials should be pretty accurate overall. There 
may be minor errors in the center of the bands due to slight 
non-linearity of the tuning capacitor but the calibrator 
should take care of this.
    The procedure will also insure the RF stages are all 
tracking for best sensitivity.
    About the intermittent oscillator, even though you 
cleaned the band switch contacts they may still be 
intermittent.  I suggest cleaning them using Deoxit D5 and 
when that has evaporated treat with Deoxit G5.  Although 
Caig says its for gold contacts in fact its a protective 
treatment for _all_ contacts after they have been cleaned 
with D5. My experience with D5 is that it will clean some 
contacts that will become intermittent or noisy again after 
a day or so.  In the past I've used General Cement Tuner-Lub 
to protect them after cleaning with Deoxit. That has worked 
very well and you may also want to try that. Also, when you 
clean the contacts work the switch back and forth many times 
with the contact cleaner still wet. That will tend to polish 
off whatever is on the contact.  Its still possible that 
there is something else wrong but give this a try.  If you 
can get use of a good tube tester check the tubes.  Bad 
tubes are not as frequent as sometimes thought but a really 
weak one will cause trouble.
    This looks like a good little receiver and worth some 
effort to get working right. Keep in touch and let me know 
how its coming.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com