[ARC5] A Heterodyne Sweep Generator

[Fuqua, Bill L]

  If you look at the schematic for the MC1350P and the NE602  you will see that they are very similar.
I used to use the 1350 for a phase discriminator over 30 years ago. I fed the oscillator into the gain pin.
 Later I used a a MC1357 for a limiter and phase discriminator. The quadrature detector was actually an analog multiplier with an external pin for
one of its inputs. This allowed a reference signal to be supplied to the multiplier.
 Unlike the MC1358 which had internal connections to both inputs and the external pin was to be connected
to the quadrature LC circuit. 
  
  73
Bill wa4lav

________________________________________
From: Geoff [geoffrey at jeremy.mv.com]
Sent: Thursday, March 13, 2014 7:00 PM
To: Fuqua, Bill L; David Stinson; ARC-5
Subject: Re: [ARC5] A Heterodyne Sweep Generator

Mine used audio AGC to the MC1350 IF amp. Built one for 80-15M including
WARC, fun little things.

Carl




----- Original Message -----
From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
To: "David Stinson" <arc5 at ix.netcom.com>; "ARC-5" <arc5 at mailman.qth.net>
Sent: Thursday, March 13, 2014 1:18 PM
Subject: Re: [ARC5] A Heterodyne Sweep Generator


>  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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