[amsat-bb] Re: AO51 mode: 23cm SSB up / 70cm FM down ?

Greg D. ko6th_greg at hotmail.com
Tue Sep 9 00:04:45 PDT 2008

Hi Henk,

I always like to try new modes, but are you sure that your uplink isn't working?  I've got an ICOM 1271A, which also runs 10w.  It feeds a homemade 18 turn helix (http://home.wavecable.com/~ko6th/IMG_0138.JPG) after about 60' of 1/2" hardline and another 10' of RG-8-like stuff to get out of the house, and to run around the rotor.  There can't be much left of the signal after all that, and I have no problem getting into AO-51 with this setup, even at low elevations (long distance).  I heard myself this evening down below 10 degrees with it.

Are you able to hear the downlink when others are on the bird?  The hardest part for me with mode LS has been on the "S" side - finding the downlink and tracking it through fades and the nasty doppler shift.  My downconverter is off by about 50khz, and the IF receiver is a bit deaf, which doesn't help either.  

But, if you can hear the downlink, perhaps it is the uplink that is at issue.  What sort of cable run do you have between the rig and the antenna?  How many elements in the quad?

Greg  KO6TH

> Date: Tue, 9 Sep 2008 07:36:41 +0200
> From: hamoen at iae.nl
> To: amsat-bb at amsat.org
> CC: pa3guo at amsat.org
> Subject: [amsat-bb]  AO51 mode: 23cm SSB up / 70cm FM down ?
> Dear all,
> I was considering to submit the following mode to the AO51 command team.
> (I did this already a while ago but my emails seems to bounce)
> Objective: provide a means for stations with small ERP to test their
> 23cm uplink channel into AO51.
> Uplink   23cm SSB (!)
> Downlink 70cm FM (preferably 435.300)
> With 23cm FM uplink I seem not to have enough ERP to get over the sat.
> That is, I never made it through the squelch level of the AO51 receiver
> (using Kenwood TS2000X/10W, and a small cubicle quad antenna only).
> In SSB mode with the squelch open I could try even CW to see how weak my
> uplink is. Maybe just below squelch level, maybe far down in the noise.
> And: with SSB we can even have multiple stations testing their links at
> the same time !
> Any thoughts of anyone else before I submit this request ?
> Henk, PA3GUO
> (... and I have a 33 elements beam now)
> http://www.pa3guo.com
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