[Boatanchors] Alignment Question: High Side of Osc. vs Low Side

[Richard Knoppow]

----- Original Message ----- 
From: "Mark Johnson" <mvjohn at sympatico.ca>
To: <boatanchors at mailman.qth.net>
Sent: Monday, June 03, 2013 1:21 PM
Subject: [Boatanchors] Alignment Question: High Side of Osc. 
vs Low Side


> Team,
>
> An issue that has always been unclear to me when doing an 
> alignment of a receiver. Some receivers have you adjust 
> the local oscillator frequency to the high side of the 
> incoming signal and some to the low side. Some receivers 
> have you do either depending on the band your aligning. 
> Example I'm checking out a Hallicrafters SX-110 and the 
> oscillator frequency is adjusted to the high side of 3 of 
> the 4 bands and the low side on the 4th band.
>
> I understand the theory but how do I actually know or test 
> for this during the alignment process? That is, if 
> instructed to adjust the oscillator to the high side vs 
> the low side, what do I test for or do to insure I'm on 
> the high side?
>
> Thanks very much.
>
> Mark VE3LU/VE3DJU

     The surest way is to listen to the LO on another 
receiver.  You can use a signal generator and try to find 
the images but that can sometimes be misleading.  Most of 
the time setting the LO lower than the signal is done 
because it makes it easier for the oscillator to put out 
strongly or because of problems with stability.  The 
annoying thing is when the instructions don't tell you which 
side to set up on, for instance the Hammarlund HQ-120 and 
129 don't say a thing and yet both set above the signal on 
the four lower bands and below it on the two top bands.  It 
does make a difference.


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