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RE: AO-14, UHF antenae revisited



> Well, I tried the empirical method of testing, in the true 
> tradition of the
> Aussie "bush", using a 1/4 wave GP as a baseline. Guess what?

:-)

> Can't hear a damned thing on either!! I was listening for 
> AO-14 last night
> around 2144 EST and didn't here a thing. Couldn't trigger a downlink
> either.(operating full duplex) with 10w to an 11 element beam.

I haven't worked it for a while.  Might have to get back on tonight, to
double check the bird for tomorrow's little session atn the hamfest. :-)
> 
> 
> The problem resolves to;-
> 
> [i]Neither antenna works? They both have reasonable 
> VSWR...about 1.5 / 2.0 :1.

Could be a radiation angle issue.

> 
> [ii]Wrong frequencies? 145.975 up 435.070 down, with and w/o doppler
> correction.

Freqs are correct.

> 
> [iii]Tracking error? Winorbit 3.6,
>      UO-14
>      1 20437U 90005B   00125.15817591  .00000389  00000-0  
> 16588-3 0  5453
>      2 20437 098.4144 193.6270 0011124 350.4463 009.6505 
> 14.30416019536570
> 
>      gave me AOS at 2144EST Australia (+10) 1144utc at QTH 
> 32d 50.328' South,
> 145d 52.726' East.

Hmm, I haven't got up to date Keps with me ATM, so can't check from here
(without a bot of mucking around :) ).

> 
> Is the bird still in fm mode, did I get the freqs right, did I get the
> tracking right? perhaps some kind soul could enlighten me?

What are you using for the Rx?  How much (and what type of) coax do you have
between the antenna and the 70cm rx?

I routinely work the bird with small beam pointed at it, and a couple of
watts on the uplink.  The beam is the difference between hearing it and not
hearing it a lot of the time.

As an experiment one day, I put a 2m 1/4 wave (which has a nice high angle
of radiation) on a magnetic mount on the roof of the car and went mobile
during a pass.  Installed a diplexer and connected up the 2 rigs for 2 and
70.  On this setup, I heard very little on the downlink.  Disconnected the
Rx and put a 1/2 wave (modified UHF CB rubber duck!) on top of the rig and
stuck it out the window and could clearly hear the downlink.  Seems the 3.6m
of RG-58 was enough to kill the downlink. :-)  Mind you, 2 watts into the
1/4 wave was ample for the uplink.

Your problem may have something to do with feedline losses.
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