[AMRadio] Halli HT37 Phasing Mod problem


David Knepper collinsradio at comcast.net
Tue Nov 27 22:18:11 EST 2007


Gary, my late father-in-law (W3MGU) used a loud mechanical clock with a 
microphone to listen to the other sideband.  He then adjusted the sideband 
supression for the weakest tick-tock.


Dave, W3ST - W3CRA
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----- Original Message ----- 
From: "Gary Schafer" <garyschafer at comcast.net>
To: "'Discussion of AM Radio in the Amateur Service'" 
<amradio at mailman.qth.net>
Sent: Tuesday, November 27, 2007 9:16 PM
Subject: RE: [AMRadio] Halli HT37 Phasing Mod problem


> If you are trying to align it using a tone and looking for a flat response
> on the scope and you have any hum in the circuit you will never get it
> aligned. Hum can come from poor filter caps in the power supply or audio
> leads picking it up.
>
> The best way that I have found to align phasing rigs is to talk into the
> mike while listening to the opposite side band and tune things for minimum
> (best side band suppression). A nice long ooooooh works good. You will 
> need
> to switch side bands and do the same on the other as they interact. You 
> can
> tune it for really great suppression on one side band while the other one
> won't be so great.
> Find the point where the suppression is nearly equal on each side band 
> while
> listening to the opposite side.
>
> Sometimes the Rf phasing coil will have little effect when tuning it. It
> depends on how tightly it is coupled to the next stage.
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: amradio-bounces at mailman.qth.net [mailto:amradio-
>> bounces at mailman.qth.net] On Behalf Of DOXEMF at aol.com
>> Sent: Tuesday, November 27, 2007 11:59 AM
>> To: amradio at mailman.qth.net
>> Subject: [AMRadio] Halli HT37 Phasing Mod problem
>>
>> Hello,
>>  I have been trying to get this like new HT37 on the air for awhile.
>>  The audio phasing modulator has been near impossible to properly 
>> ballance
>> espeially using the manual instructions.
>>  So far have replaced a leaky low pf brown drop silver mica
>> that corrected some of the problem but still am not able to get a 
>> properly
>> phased output from the modulator.
>>  The audio seems ok up up to the rf stage where it won't align. The
>> carrier osc is on freq ok but the carrier phasing adjustments do not work
>> out.
>>   Where would be a good location to apply a ballanced audio signal to
>> bypass most of the original circuit?.
>>   Has anyone come up with an alignment procedure using modern test gear?
>>
>> Thanks,
>> Bill,
>> KB3DKS/1
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