[amsat-bb] Financial arguments about full duplex

Patrick STODDARD (WD9EWK/VA7EWK) amsat-bb at wd9ewk.net
Tue Jun 28 16:35:08 UTC 2016

Hi Jerry!

I had written about using certain Chinese-made dual-band HTs to
work AO-85 full-duplex a few months ago on this list, and an
article based on those posts appeared in a recent AMSAT Journal.
But that is not the only way, or even the cheapest way, to get on
AO-85 (or other U/V FM satellites) full-duplex. I, like many others
reading this list, have worked stations using two Baofeng HTs and
a homebrew 2m/70cm Yagi like the WA5VJB design. Two Baofengs
should be in the $60 to $70 range, and a homebrew Yagi a few
dollars more in parts. Basically, for less than $100, a ham can
have a station capable of full-duplex operation for FM satellites.
If someone already has an HT, then the costs for a second radio
and parts for a 2m/70cm homebrew Yagi become more like $40 or $50.

As I mentioned in other recent posts on here, I worked an FM satellite
pass during Field Day half-duplex, on LilacSat-2 (like SO-50,
using a 2m uplink and 70cm downlink). It can be done, but many of us
hear the complaints from those who have tried the half-duplex
approach unsuccessfully. If anything, the advice about working
FM satellite full-duplex is an attempt to set expectations for success
on these satellites. Yes, half-duplex can work, but full-duplex
works better.

As for the linear transponders, that will take different equipment
where there really isn't the same inexpensive option as we have with
the Chinese-made HTs for FM satellites. There are options to hold
down the costs for equipping your station to work these satellites.
Using a pair of all-mode HF/VHF/UHF transceivers, or one of those
transceivers with a software-defined receiver, are a couple of
examples of this. But it can be done.

Good luck, and 73!

Twitter: @WD9EWK

On Tue, Jun 28, 2016 at 3:32 PM, Jerry Conner via AMSAT-BB <
amsat-bb at amsat.org> wrote:

> That is what I have done, built a cheap antenna.  I have a Chinese radio
> and I have made contacts on SO-50, half duplex.  I DO NOT get on the linear
> birds because primary I do not have the means to run 2M/70CM SSB. I can
> also understand that it would near impossible to effectively make a contact
> But newbies can/should be given guidance in the form of Elmers. Not being
> told they are not welcome if they don't have the equipment others have.  By
> the way check the prices an arrow antenna that will give someone the best
> chance to get into AO-85 with a Cheap Chinese radio is about $150.00.
> I love VHF/UHF but I can't do much more than be a spectator at this point
> due to the equipment required.  I will get there eventually.
> I am just trying to point out that not everyone has the ability and may
> never have the ability work the satellites with the gear that others have.
> I would love to have a way to do so but for now it is not in the cards in
> my household.  I am OK with that.
> So when the arrows start flying try not to hit the people that you should
> be trying to bring in the fold to help, in any way they can, put more
> satellites in orbit for us all to enjoy.  Just my viewpoint from down here.
> 73
> Jerry W4JWC

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