[amsat-bb] Re: Active FM Sats

Patrick STODDARD (WD9EWK/VA7EWK) amsat-bb at wd9ewk.net
Tue Jul 5 08:43:01 PDT 2011


> Show me an all-mode HT that retails for the same sort of price and is the
> same sort of size as an FM HT and I might be interested.  Otherwise, to
> get UHF and VHF SSB I'm stuck with an inconveniently large radio which
> is only really useful for the twenty minutes a day that a satellite is
> overhead.

An all-mode HT.... doesn't exist at this time.  Probably the closest you get
in an HT would be a TH-F6/TH-F7 with its all-mode receiver, but still an FM
transmitter.  You could attempt transmitting CW by keying that transmitter,
but it's not ideal with the 5 kHz tuning steps at FM on that radio (SSB
tuning steps on a TH-F6/TH-F7 can go as small as 33 Hz) and no
provision for computer control.  Otherwise, an FT-817 gets close to the
HT size, is an all-mode transceiver at HF and 6m as well as 2m and
70cm, and would qualify as a radio that can be used more than "twenty
minutes a day that a satellite is overhead."  It does cost more than an
FM HT, but FT-817s should be available on the secondhand market
as they have been in production for a decade.  Even two FT-817s as
a portable all-mode full-duplex satellite station are not what I - or
many - would consider "inconveniently large".  If you prefer computer
control, the 817s have Yaesu's CAT port to allow for that.

> Not to mention the difficulty involved in tuning the radio and aiming the
> antenna.  Doesn't the Doppler shift mean you need to constantly
> retune?  How do you manage to do that, key the mike and point the
> aerial, *and* have enough brainpower left to make a contact?

You are having to make minor adjustments to your frequency - or
frequencies - when working SSB or CW via satellite.  If you follow the
so-called One True Rule, you're making the adjustments to one of
the two frequencies (usually the higher of the two frequencies).
Everyone had to work SSB/CW via satellite this way in the past,
before the advent of computer-controlled stations, and it is still an
option today even if some (many?) discourage it.

If you've worked FM satellites, you already know about the "key the
mike and point the aerial" part.  Then just focus on the QSO in
progress.  Don't try to remember everyone you worked - leave that
on an audio recorder, or recorder app for a mobile phone or iPod
type of device or laptop/netbook, and play it back later to update
your log.

Pedro EB4DKA has posted a lot of useful information for working
SSB via satellite.  I read the writeups and watched the videos as I
started out on the SSB birds.  I don't operate using a mobile setup
like Pedro does, but with one directional antenna (an Elk 2m/70cm
log periodic) through a diplexer to my two-radio setup.  I've
uploaded some videos working those satellites at:


I used both of my FT-817NDs on the SSB passes shown in these
videos, but on occasion swap out the 817 I use as the receiver
and put my TH-F6A in its place.



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