[ARC5] A Heterodyne Sweep Generator

[Dennis Monticelli]

Yes, they did.  The intended application was portable where strong signals
were unlikely to be an issue and low receive power consumption was
important.  It was a good choice for the job.  I think the KX-1 was similar.

Dennis AE6C


On Thu, Mar 13, 2014 at 7:04 PM, Fuqua, Bill L <wlfuqu00 at uky.edu> wrote:

>   The ELKRAFT K1 applied the agc to the SA602 Mixer.
> 73
> Bill wa4lav
>
> ________________________________________
> From: arc5-bounces at mailman.qth.net [arc5-bounces at mailman.qth.net] on
> behalf of Fuqua, Bill L [wlfuqu00 at uky.edu]
> Sent: Thursday, March 13, 2014 9:40 PM
> To: Geoff; David Stinson; ARC-5
> Subject: Re: [ARC5] A Heterodyne Sweep Generator
>
>   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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