Fw: [Elecraft] Peaking L34 (IF amplifier)

[Geoffrey Mackenzie-Kennedy]

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" <gmk at gm4esd.fsworld.co.uk>
To: "David C Dawson" <ve7hp at shaw.ca>
Cc: "Elecraft Discussion List" <elecraft at 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