[ARC5] A Heterodyne Sweep Generator

[Fuqua, Bill L]

  In some QRP transceivers they feed the AGC back into the input pins.
By reducing the input bias voltage the gain is reduced. I can't recall the exact radios
that used this scheme but they derived the AGC voltage from the audio and applied
it to the mixer which had a transformer directly connected to the input pins and a bypass to ground
on one side. The AGC was applied to the bypassed side of the input transformer. 
  However, I would suggest that you set up the system for constant output and use a variable
attenuator between the output and device to be tested along with the appropriate series resistance
to match the input impedance of the device under test. 

73
Bill wa4lav

________________________________________
From: arc5-bounces at mailman.qth.net [arc5-bounces at mailman.qth.net] on behalf of David Stinson [arc5 at ix.netcom.com]
Sent: Thursday, March 13, 2014 11:20 AM
To: ARC-5
Subject: Re: [ARC5] A Heterodyne Sweep Generator

> The NE602 has a useful amount of conversion gain - an advantage
> in
> receiver applications (which is what it was designed for) - and
> often a
> disadvantage in frequency-conversion applications,...

Can the gain be throttled with negative feedback?
I've used them but never looked into this.
Back to yard work!

73 Dave AB5S


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