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Re: Dualband HT info



At 10:01 PM 01/08/2000 -0600, Peter D. Bayne wrote:
>Scott wrote:
>
> >I am looking for a new HT that will allow me to work ao-27 and so-35.  What
> >HT's are people using that allow full crossband duplex, etc?
> >
>You wrote:
>Scott, the HT commonly in use for the AO 27 bird is the Kenwood TH-D7
>which allows full duplex mode to work the up-link and downlink
>frequencies on both 144 and 70 cm. I have also had good success with the
>Arrow Satellite antenna with the duplexer built in using the Kenwood HT.
>Although the power output is limited to 5 W that is more than adequate to
>work AO 27 provided that there aren't any QRO enthusiasts in the arena.

One of the nice things about a single channel FM bird, is you don't have to 
hear your down link in order to use the transponder.  Some of the half 
duplex transceivers will work just fine for these birds, and are generally 
much less expensive than the various HTs capable of full duplex operation.

Personally, I've had a great deal of success with a Yaesu FT50R.   The 
FT51R is a full duplex rig, but as I stated, a half duplex rig will work 
just fine.

If you program in a series of paired frequencies, you can tune in "memory 
channel steps" from AOS to LOS.

For revue sake, and for those interested, here are some suggested pairings 
for AO27 and SO35.

+++++++++

Working AO27

You should program your HT with 5 frequency pairs for working AO-27.  Start 
with the first pair, using a non-standard split, and tune to the next one 
as the pass progresses.

Downlnk -  Uplink
_________________
436.805 - 145.845
436.800 - 145.850
436.795 - 145.850  Mid Pass
436.790 - 145.850
436.785 - 145.855

The Doppler shift on the 70-cm downlink can be a little more than 10 
kHz.  The 2-meter Doppler is close to 3 kHz.


++++++++++

Working SO35

If you are using a scanner to listen, or an HT which only tunes in 5 kHz 
increments, use this table as a guide. Since the downlink frequency will be 
closest to 145.825 during most of the pass, break the pass into a little 
over 3 minute chunks, and increment your programmed pairs (you will need to 
program nonstandard splits) during the pass for best centering in the 
passband of your uplink signal.


Downlink  --  Uplink
--------------------
145.830      436.280
145.825      436.285
145.825      436.290  Satellite directly east or west of you
145.825      436.295
145.820      436.300


The first or last pair may not be required, depending on your latitude.


73, Mike


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