[Microwave] Doubling from 12 to 24 GHz

[Dave Brown]

Tks Jerry- that aligns with not being aware anything like this  has ever
been used in the amateur world at higher power levels. I guess I'll look at
snowflaking the 12GHz amp down to 10 GHz as its too tempting to just leave
it unused.  Even if it dies in the attempt..!     Which means I need to  go
back to looking into  generating lower power on 24GHz for starters. I have a
couple of 23GHz ODUs ex commercial service that use ~11 GHz doubled from
Gunns for both TX and the RX LO but at low (10s of mW at most) levels, so
will see if the doublers can be isolated from the 11 GHz drive source so as
to feed in an external source  instead.
73 Dave, ZL3FJ

-----Original Message-----
From: microwave-bounces at mailman.qth.net
[mailto:microwave-bounces at mailman.qth.net] On Behalf Of Dr. Gerald N.
Johnson
Sent: Friday, August 04, 2017 12:15
To: microwave at mailman.qth.net
Subject: Re: [Microwave] Doubling from 12 to 24 GHz

Most frequency doublers or triplers work at milliwatt levels, often using a
couple diodes fed 180 degree out of phase RF, a full wave rectifier that has
a fairly strong 2x and other even harmonic outputs with very little
fundamental. Triplers often use two anti parallel diodes as shunt clippers
to convert the sinewave drive to something approaching a square wave that
has a spectrum of fundamental and odd harmonics. The clipper can be a
transistor or MMIC. There has been some work that shows the distance between
the output of the clipper and the harmonic filter can enhance the desired
harmonic, I think mentioned on the W1GHZ web page from quite some time ago.

A push-pull amplifier with the active device outputs connected in parallel
instead of 180 degree out of phase would be a strong doubler, and with the
normal connection would minimize the 2nd harmonic but if the output network
presented a mismatch impedance to the active devices at the fundamental and
impedance matched the third harmonic would be a very effective frequency
tripler.

I'm not aware of any passive multipliers that would take in several watts,
nor any diodes that would absorb that much power and have a fraction of an
RF cycle switching time. A junction that could handle several watts would
have so much capacitance because of its large cross section that it would
not work at 12 GHz at all, probably not 1 GHz.

73, Jerry, K0CQ

On 8/3/2017 6:30 PM, Dave Brown wrote:
> I'm looking, ideally,  for some surplus piece of hardware that can be 
> used (with a retune?) to do this.  I have up to several  watts at 12 
> GHz available from an amp ex some surplus analog TV link gear and want 
> to use that doubled to make a 24 GHz  TX. I can generate a good stable 
> 12 GHz drive signal for the amp so that's no issue but wondered if 
> there's some surplus piece of gear around to use for the doubler 
> stage. There's nothing like this available down here in ZL. The 12 GHz 
> amp output is SMA, but I expect anything surplus that could be used 
> for a doubler would likely  be waveguide
> input-  again, no issue,  as I have 12 GHz and 24 GHz  coax to w/g 
> transitions available.
>   I can also come up with several watts at 8 GHz and triple, if 
> surplus  gear to triple with is more readily available.
>   All suggestions welcome.
>   73
>   Dave, ZL3FJ
>
>
> ______________________________________________________________
> Microwave mailing list
> Home: http://mailman.qth.net/mailman/listinfo/microwave
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Microwave at mailman.qth.net
>
> This list hosted by: http://www.qsl.net Please help support this email 
> list: http://www.qsl.net/donate.html
______________________________________________________________
Microwave mailing list
Home: http://mailman.qth.net/mailman/listinfo/microwave
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Microwave at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html