[NLRS] [Mw] 2304?

[Dr. Gerald N. Johnson]

On 12/29/2016 2:47 PM, Ben wrote:
> Gerald et al,
>
> A few months ago I bought an EDUP 2.4 GHz Broadband amplifier, a WiFI
> signal booster
> (http://www.ebay.com/itm/EDUP-EP-AB003-2-4G-Broadband-Amplifiers-8W-/282306573527?rmvSB=true)
> for use on 2304 MHz for $30.  This amplifier has 8 watts output and
> runs off of 12 v.d.c.  The gain may be high for your needs, but you
> can fix that with a pad.  The amplifier is listed as 2400- 2500 MHz,
> but all I could detect at 2304 MHz was a couple of dB loss in gain
> with the output still at 8 watts.  The input drive level is given as
> 3 dBm min. to 20 dBm max.  I did run and input/output curve which
> looked linear, but I haven't run a two-tone linearity test as of yet.
> Working at 2304 is a bit different than HF or even VHF in that if
> your IMD was as bad as 20 dB, you won't have to worry adjacent
> channel interference 2 or 3 I.F. bandwidths away; i.e. there probably
> isn't anyone operating there anyway.

Interesting. Bits of RG-174 should make reliable and simple 2.3 GHz 
attenuators, maybe even RG-58. I have used RG-58 to drop the drive to a 
tube PA at 432 in decades past.

I wrote a paper for CSVHF a few years ago on setting drive for 
transverter signal quality primarily to sound better at the other end 
without sacrificing too much weak signal performance. I proposed looking 
for peak clipping using a diode detector and audio bandwidth scope. I 
titled it: "Setting Transverter Drive for Better Signal Reports." CSVHF 
2012, on line.
http://www.geraldj.networkiowa.com/papers/2012/TXanticlipping.pdf
>
> I have looked at combining two of these amplifies to get 15 watts or
> so.  I'd start by building strip line, branch line couplers, with
> copper flashing lines suspended between two ground planes, similar to
> the way I made my ring-hybrid for a rat race mixer for 2.3 GHz in my
> QST article with W5HN somewhere around 1973.  The ground planes can
> be G-10 PC board or just about anything else as the strip line uses
> the air dielectric between the top and bottom ground planes.  You can
> build these couplers in an hour with a soldering iron and a pair of
> scissors to cut the copper flashing.  I would then stack two of the
> amplifiers horizontally with the input and output couplers mounted
> vertically.  The two inputs are phase separated by 90 deg., but the
> output couple shifts the signal 90 deg. back to combine the two
> amplifiers in phase.  Using 4-way splitters/combiners with 4
> amplifiers will get you about 30 watts for $120.  Just some
> thoughts.

I've been looking at wide band impedance matching with tapered lines and 
I have found seom references using planar tapers for four way splitters. 
I've written some software to analyze such a taper and for a 2:1 
impedance ratio its saying a quarter wave linear taper works as good as 
a 4 wavelength taper. I'm not sure I believe the results yet.
>
> Using the 2 ft. x 3 ft. reflector antenna will give you about an 12
> deg. horizontal beamwidth, three times as wide as your 18 inch DSS
> dish at 10 GHz and three times easier to aim.

Its going to take getting a better rotor than Ham-M style with its 15 
degree brake steps when I put it up on a tower.

Thanks for the ideas.

73. Jerry, K0CQ
>
> 73's...Ben/K4QF
>
>
> -----Original Message----- From: Microwave
> [mailto:microwave-bounces at mailmanlists.us] On Behalf Of Dr. Gerald N.
> Johnson via Microwave Sent: Wednesday, December 28, 2016 8:20 PM To:
> Microwave List<microwave at mailmanlists.us>; NLRS
> Reflector<NLRS at mailman.qth.net> Subject: [Mw] 2304?
>
> I brought home the 2304 1 watt DEMI transverter from MUD in October.
> I haven't yet fired it up. Been working on antenna ideas some with a
> 2x3 ft WiFi skeleton reflector including variations on K4QF's log
> period feed that I published in the proceedings for CSVHF and MUD
> this year. There is still work to be done there.
>
> Living 165 miles from the twin cities and at least that far from the
> Quad Cities, near the Boondocks
> (https://www.flickr.com/photos/22711505@N05/24151165432) looking at
> the propagation data in the International Microwave Handbook and 2304
> contest activity for the last couple years of ARRL contests it
> appears to me that 1 watt even with 20 dB antenna gain isn't going to
> make those paths work, there might be a chance of working a couple
> rovers from home, but that can't run up lots of points. And aiming a
> 20dB gain antenna won't be easy.
>
> Looks like if I get on I'll need to either rove to Chicago or the
> twin cities or add a PA, perhaps 50 watts to stay in the low power
> class in ARRL contests. Looking at VHF conference and MUD
> publications for the past decade or so, it appears the most popular
> PAs come from Pyro Joseph as the Spectrian boards, single or grouped
> for several hundred watts output. Are there other practical options.
> There was a post a few weeks ago about another package but when I
> looked at the conversion article it looked almost as easy to build
> from scratch as to drag the PA from 1900 to 2304. Looking at
> Mouser.com I see some reasonably priced 25 to 50 watt GAN parts
> without internal matching so they are good from HF to a few GHz
> depending on the part. Has there been any work making them work for
> multiple bands? Most of the solid state amplifier circuits I've seen
> are single band using shunt capacitors and a length of line,
> sometimes a quarter wave as a Pi network transformer and low pass
> filter. That makes them single band. I have some hardware on hand for
> 902 and 1296 that it would be nice to get on too, but no working
> power amps.
>
> So what are my options for power on 2304? Used Spectrian, or pay Pyro
> Joseph's price and go from there?
>
> 73, Jerry, K0CQ _______________________________________________
> Microwave mailing list
> https://www.mailmanlists.us/mailman/listinfo/microwave
>