[amsat-bb] L band gear

Thu May 14 13:43:04 UTC 2020

Hi John 
Not familiar with the DEMI converter. I’ll look it up. 
The idea of reducing feed line loss has always appealed to me. One of my AO-13 L-band experiments was a 4’ long helix, rear mounted, with a brick M57762 amplifier on the boom extension behind the cross boom serving as a counterweight for the helix. Minimum amp-ant feedline loss. The transverter was in the shack. I used the transverter to amplifier feedline (~40’ rg213) as an attenuator to reduce the transverter’s power output (too strong fir the brick) to the correct level for the brick. (Worked properly, but the 10W output was really too weak for the high orbit sats). Man, that was fun stuff. 
I have toyed with a similar concept for a fixed station now, with a much smaller antenna. The present transverter is too big and clunky to mount in a box with the amp on the tower, but the W1GHZ transverter can be quite small. Not a real high priority but interesting nonetheless. 

Ed Krome K9EK

Sent from my iPhone

> On May 14, 2020, at 8:35 AM, John Kludt <johnnykludt at gmail.com> wrote:
> 
> 
> Ed,
> 
> Just curious if you have looked at the DEMI L band TX upconverter.  This was designed for the L band satellite uplink and is a transmit only converter.  The IF can be 28 MHZ, 50MHz or144MHz.  What I like about the idea is there is a verion design to be mounted at the antenna which gets around the feedline loss issue at 1267 MHz.  Still looking at it - as anyone purchased one?
> 
> John
> 
>> On Thu, May 14, 2020 at 8:28 AM Ed Krome via AMSAT-BB <amsat-bb at amsat.org> wrote:
>> Hi Zack
>> My comment about how much easier it is to get to 23cm today was based on W1GHZ’s transverter. Great little device. I have been meaning to try mine on 1267. Also have thought about using my DigiLO as the LO, since it goes to 6ghz. It was slated for a 10ghz transverter but I don’t think it cares. You and I should compare notes more often! W1GHZ also has some multiplier boards that would simplify use of a lower freq as a base. Not (yet) familiar with the Arduino based Si synthesizer. Need to look for that thing. Do you have a link? Oh great, a new project to grab my interest and devour limited (time) resources. 😁
>> The amplifier I referenced was my article. Easy to build, works great and 30 watts. 
>> OK, so I’ll dig out and sweep/tweak the W1GHZ transverter and see what happens. Stay tuned. 
>> 
>> Ed Krome K9EK
>> 
>> Sent from my iPhone
>> 
>> > On May 14, 2020, at 12:00 AM, Leffke, Zachary via AMSAT-BB <amsat-bb at amsat.org> wrote:
>> > 
>> > In line with Ed's thoughts on homebrew....
>> > 
>> > somewhere on my todo list is to take a look at the W1GHZ 1296 transverter kit (SUPER cheap to get on the air, great documentation) with an eye towards 'tweaks' for 1267(ish).  Very high(hi) level ideas include different LO (I think, but haven't confirmed, the digiLO may have an output suitable for this) to produce a useable IF.  I also just discovered the Si5351 arduino controllable synthesizer (~$10 for a breakout board), which with a few multiplication stages and some filtering, might make for a suitable base chip for a configurable custom LO design on the cheap (there's probably already a QEX article somewhere for this).  The builtin PCB hairpin filters on the 1296 transverter might be an issue....but also might not be an issue, and maybe also 'tweakable' (razorblade style....or maybe with a little copper foil tape).
>> > 
>> > W6PQL has some good reference designs as well for the RA18H1213G Ed mentioned (he might also be the author of the referenced articles, not sure haven't checked).
>> > 
>> > Wanted to get the basic idea out there in support of the homebrew concept:  W1GHZ transverters for satellite bands.....the idea might be extendable to higher bands as well for future birds (i.e. GOLF) for cheap access to microwave for satellite....the pipecap filters used on higher frequencies are probably more easily tuneable than the PCB filters on the lower bands...so in a way, the higher bands might be easier to tweak for the satellite sub bands.
>> > 
>> > As is probably obvious, not fully thought through idea, so not sure of the feasibility, and currently pretty far down on the todo list.....but I'd be happy for someone to beat me to the punch!  Adventures in this area would make for some great articles for the Journal and help spread the word and stimulate some microwave activity.
>> > 
>> > -Zach, KJ4QLP
>> > -- 
>> > Research Associate
>> > Aerospace & Ocean Systems Lab
>> > Ted & Karyn Hume Center for National Security & Technology
>> > Virginia Polytechnic Institute & State University
>> > Work Phone: 540-231-4174
>> > Cell Phone: 540-808-6305
>> > 
>> > 
>> > -----Original Message-----
>> > From: AMSAT-BB <amsat-bb-bounces at amsat.org> On Behalf Of Ed Krome via AMSAT-BB
>> > Sent: Wednesday, May 13, 2020 10:22 PM
>> > To: 73 Bob W7LRD <w7lrd at comcast.net>
>> > Cc: amsat-bb <amsat-bb at amsat.org>
>> > Subject: Re: [amsat-bb] L band gear
>> > 
>> > I’m a bit surprised that so few are using portable (and no homebrew) 1267. Here’s an alternative, homebrew style. Something old and something new. 
>> > Antenna: 12el hb yagi with folded dipole DE, mounted on top of Arrow with 8” fiberglass rod spacers
>> > Amplifier: hb brick amp with RA18H1213G. See AMSAT Journal Jan-Feb 2019 for construction details. Can do 30W, but never use that much.
>> > Transmit-converter: ancient hb, dbm + discreet transistor amps. Would be so much easier today with MMIC’s. ~1/2W out. Originally built for AO-10 and used  a lot on -10 & -13
>> > RF (2M) source: Baofeng UV5R+ ht. Why? Because that thing has no problem transmitting slightly below the 2M band edge. The trans-converter was crystaled so 145 in = 1269 out. AO92 is 1267.x, so the trans-conv requires 143.x input. In the AO10&13 days, the driver was a Drake T4X driving an hb 2M transverter. Complicated, but as a fixed station (100+W out from 2x7289) it worked well. 
>> > The whole portable rig runs on a single drone battery. 
>> > Now if I could just get around to operating once in a while. 
>> > 
>> > Ed K9EK
>> > 
>> > Sent from my iPhone
>> > 
>> >> On May 13, 2020, at 12:53 PM, 73 Bob W7LRD via AMSAT-BB <amsat-bb at amsat.org> wrote:
>> >> 
>> >> Hi all-  I would be curious to know what "everyone" is using for L band gear.  Perhaps others would like to know.  example I run
>> >> IC-910- at 10W
>> >> 70 feet of LMR600
>> >> 24 element looper yagi horizontal polarized
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>> > _______________________________________________
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>> _______________________________________________
>> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
>> to all interested persons worldwide without requiring membership. Opinions expressed
>> are solely those of the author, and do not reflect the official views of AMSAT-NA.
>> Not an AMSAT-NA member? Join now to support the amateur satellite program!
>> Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb