[Hallicrafters] sx101 mk III alignment

[Edward B Richards]

Jack;

This is not model specific but applies to almost any alignment. The
object is to insert a weak signal on the correct frequency and tune the
RF and IF stages for maximum output. IF alignment should be done first by
inserting a frequency into the mixer grid the same as the IF frequency.
This is often, but not always 455 kc for single conversion receivers.
(For dual or triple conversion receivers do the last IF first and work
backward toward the antenna) This is usually done by using a blocking
capacitor in series with the sig gen output, applied to the mixer
(converter) section of the tuning capacitor. This is the center section
for one RF amplifier radios and the second from the front for two RF
stages. Metering can be done by monitoring the AGC voltage with a
negative reading VTVM or by connecting an AC voltmeter across the speaker
terminals. Tune (adjust) all adjustments for max reading on the meter.
Some procedures will call for going back to de-tune one stage some
specific amount. Keep the gain controls wide open and use the smallest
signal that you can see. Sig gens are not calibrated for frequency so use
a counter across the sig gen to determine frequency. I hope this helps.

When tuning T1,T2,T3,T4 etc. adjust the screw or slug both ways to find
the maximum reading on the meter. You do not tune to maintain one volt,
you tune for max reading while adjusting the sig gen output to maintain a
reading around one volt.

73, Ed Richards K6UUZ
Simi Valley, Ca 93065
Home of the Air Force 1 pavilion

On Sun, 29 Jan 2006 19:56:23 -0500 "Jack Schrader" <w1jhs at midmaine.com>
writes:
> As I've said before I've lost most of what I once knew about radio 
> electronics, so here's the questions.
> 
> I have started to so an alignment of my sx101 mk III and I am 
> stumped on the first step. First thing is that when I attach the dc 
> vtvm probe to point B do I also attach the other wire in the probe 
> to the chassis, because if I do it kills the input from the signal 
> generator? Secondly, it says to maintain a 1 volt reading on the 
> vtvm while adjusting t1, t2, t3, and t4 but not how and what to 
> adjust for to maintain this one volt.
> 
> In step 2 it tells me to tune the generator through 1650kc to 
> determine the IF passband and then to set it at the center of the 
> passband. Where 'am I to listen to hear the passband and is the 
> center of the passband the null or do I determine the center of the 
> passband by  reading the outside freqs. off of the signal generator? 
> I have attached 500 ohm resistance to the speaker terminals but no 
> speaker.
> 
> Thanks for your help!
> 
> 73 Jack
> ______________________________________________________________
> Hallicrafters mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:Hallicrafters at mailman.qth.net
> ----
> List Administrator: Duane Fischer, W8DBF **for assistance**
> dfischer at usol.com
> ----
> Hallicrafters Collectors International: http://www.w9wze.org
> 
>