From tractorb at ihug.co.nz Thu Aug 3 19:30:38 2017 From: tractorb at ihug.co.nz (Dave Brown) Date: Fri, 4 Aug 2017 11:30:38 +1200 Subject: [Microwave] Doubling from 12 to 24 GHz Message-ID: <031401d30cb0$83962930$8ac27b90$@ihug.co.nz> 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 From geraldj at netins.net Thu Aug 3 20:14:30 2017 From: geraldj at netins.net (Dr. Gerald N. Johnson) Date: Thu, 03 Aug 2017 19:14:30 -0500 Subject: [Microwave] Doubling from 12 to 24 GHz In-Reply-To: <031401d30cb0$83962930$8ac27b90$@ihug.co.nz> References: <031401d30cb0$83962930$8ac27b90$@ihug.co.nz> Message-ID: <5983BC66.4090308@netins.net> 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 From tractorb at ihug.co.nz Sat Aug 5 23:44:53 2017 From: tractorb at ihug.co.nz (Dave Brown) Date: Sun, 6 Aug 2017 15:44:53 +1200 Subject: [Microwave] Doubling from 12 to 24 GHz In-Reply-To: <5983BC66.4090308@netins.net> References: <031401d30cb0$83962930$8ac27b90$@ihug.co.nz> <5983BC66.4090308@netins.net> Message-ID: <013101d30e66$5cfdb420$16f91c60$@ihug.co.nz> 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