[AMRadio] Receiver if alignment question

[Gary Schafer]

Did you modulate the signal generator with FM rather than AM perhaps? Some
of the service monitors only did FM.
If so that would fit your description of what is going on.

73
Gary K4FMX

> -----Original Message-----
> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> bounces at mailman.qth.net] On Behalf Of Jim WB5OXQ inb Waco, TX
> Sent: Sunday, July 17, 2011 1:10 AM
> To: Discussion of AM Radio in the Amateur Service
> Subject: [AMRadio] Receiver if alignment question
> 
> I am trying to make sure the vintage tube receiver I bought is aligned
> properly.
> I have the manual that came with the radio and it has alignment
> procedure in it which I followed.
> My question is in regards to the if alignment for the single conversion
> 455khz if.
> The instructions begins with removal of the 6aq8 oscillator tube from
> its socket and connecting the generator to pin 7 of the 6be6 mixer tube
> and ground.
> Set the generator to 455khz with 400hz modulation at 30%.  connect a ac
> voltmeter across the speaker.  Set the avc to off.
> Now I have a signal and tone in the speaker from the generator ( my
> Motorola am fm service monitor) and if I adjust the if coils in the
> order stated in the manual this is what I get;
> adjusting the 2 if coils each with a primary and secondary  I get the
> loudest volume and highest meter reading but when I do the signal sounds
> miss tuned and raspy.
> of I tune for the purest tone the volume is much less.  So which is
> correct?  Higher volume or clearest tone?
> The adjustments were way off from where I found them originally.  I
> doubt the factory alignment was that bad but who knows what any previous
> owner might have done?
> There is a scope in the service monitor but I did not use it and only
> used the voltmeter.  Would the scope be better?
> I followed up with a complete alignment of all 5 bands so dial
> calibration is extremely good now but I just don't seem to get the
> quality of audio I feel I should be getting.
> Broadcast stations sound overloaded even with the avc on to the point I
> have to turn the rf gain nearly to 0 on local am stations and there seem
> to be an abnormal amount of birdies on all the bands.  Weaker stations
> on any band seem ok.
> This receiver is a 1965 Lafayette HE 80 built by Trio in Japan
> (Kenwood).  It is a 14 tube receiver with a built in 6 meter converter
> and is an all mode receiver.  It does receive ssb stations fairly well
> on 6 meters on a poor antenna for that band but there are lots of
> birdies on that band.   I just wonder if I misaligned the IFs and that
> is causing oscillations where they should not be?
> Any advice will be appreciated.
> Jim wb5oxq
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