David,
For some reason my message sent to you three hours ago, see below, did not
get across the pond. Sorry for using bandwidth.
73,
Geoff
GM4ESD
----- Original Message -----
From: "Geoffrey Mackenzie-Kennedy" <[EMAIL PROTECTED]>
To: "David C Dawson" <[EMAIL PROTECTED]>
Cc: "Elecraft Discussion List" <elecraft@mailman.qth.net>
Sent: Saturday, November 18, 2006 12:23 PM
Subject: Re: [Elecraft] Peaking L34 (IF amplifier)
David, VE7HP wrote:
Now, I've come to peak the IF amplifier.
It seems to me that a signal just gets louder when I turn the slug
counter-clockwise until it hits the stop and quieter turning the slug
clockwise. If there was a peak, it was a really shallow one.
I followed the instructions and could hear the internal birdie quite
well, so peaking should not have been difficult.
--------------------------------------------------------
David,
The peak is quite broad, and in my K2 the position of the slug in L34 for
best S/N when using the 7 MHz birdie is slightly different from that when
using a signal applied to the antenna input. The reason for this can be
explained, but I won't bore you with the details. I opted to make the
adjustment using a signal applied to to the receiver's antenna input at a
frequency further up the band so that the 7 MHz birdie would not confuse
the issue.
Although I used an external spectrum analyzer which makes it easier to
tune L34, the AGC must be OFF, I suspect that Spectrogram could be used
although I have not tried this. If you are using a crystal oscillator to
provide the signal, you simply tune the receiver so that the signal
appears on the display wherever you want it in the passband, and the
weaker the applied signal the easier it becomes to make the proper
adjustment. It is not a good idea to use a 'real' signal from the antenna
to do this because its level could be changing due to QSB.
73,
Geoff
GM4ESD
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