[AMRadio] Receiver if alignment question

[Dennis Gilliam]

Hi Jim,

Perhaps your signal generator output was high enough to cause saturation of
the IF system.  You might try it again with a lot lower level, just enough
to get a meaningful detected output level.

73DG

On Sat, Jul 16, 2011 at 10:10 PM, Jim WB5OXQ inb Waco, TX <
wb5oxq at grandecom.net> wrote:

> 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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