Re: RE: [amsat-bb] 2m to 10m to 70cm converters

["John B. Stephensen" <kd6ozh@xxxxxxxxxxx>]

Varactor diodes can be used as mixers just as switching diodes can - all
mixers are nonlinear. The LO power must be much larger than the signal to be
upconverted or downconverted or the unwanted mixing products at n*f1 +/-
m*f2 get too large.

73,

John
KD6OZH

----- Original Message -----
From: "KC6UQH" <kc6uqh@cox.net>
To: "Robert Bruninga" <bruninga@usna.edu>; <amsat-bb@amsat.org>;
<pe1rah@yahoo.com>
Sent: Monday, June 06, 2005 05:36 UTC
Subject: Re: RE: [amsat-bb] 2m to 10m to 70cm converters


> Robert,
> Let us assume that you use two audio tones 900 and 1900 HZ fed into a 14
MHz
> transceiver with the resulting output being 14.000900 and 14. 001900 times
> 31 = 434.0279 and 434.0589, with the difference between the two tones of
31
> KHz.
> A varactor diode is also non linear, requiring some power through it when
no
> audio is present.
>  All SSB signals must be mixed up or down not multiplied. Also mixes on
the
> high side, if the IF is less than the mix results in the opposite
sideboard.
> Art, KC6UQH
>
> ----- Original Message -----
> From: "Robert Bruninga" <bruninga@usna.edu>
> To: <amsat-bb@amsat.org>; <pe1rah@yahoo.com>
> Sent: Sunday, June 05, 2005 9:24 AM
> Subject: RE: RE: [amsat-bb] 2m to 10m to 70cm converters
>
>
> > >>> William Leijenaar <pe1rah@yahoo.com>
> > >The biggest problem is only to get from
> > >HF on 70cm uplink.  These upconverters from
> > >28MHz to 435MHz are very rare and...expensive.
> >
> > But they dont have to be I dont think.  Remember
> > the old high-level varactor diodes.  Just one
> > active part.  Hit it with plenty of power at 14
> > MHz SSB and plenty of power at 449 MHz
> > carrier from two rigs and then filter the resulting
> > RF mess to only pass 435 MHz and you should
> > be able to get a few watts there.
> >
> > In fact, I thought these days if you cant find the
> > old high-power varactor diodes, that  you can
> > simply parallel say about 36 1N4148's to handle
> > the power and do the same thing.
> >
> > This depends heavily on people building the
> > good filters on the output to keep all
> > spurrs down.  But it should work.  This high-level
> > mixer doesnt even need a power supply.
> > It is totally passive.
> >
> > I'd love to have time to experiment with this,
> > but alas, no time...
> >
> > de Wb4APR, Bob
> > ----
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