[amsat-bb] Re: "Newbie" Need's Help working AO-07

Alan Sieg WB5RMG wb5rmg at somenet.net
Tue Dec 30 19:27:22 PST 2008

N0FJP said:
> I am new to working the Sats so if I am in need of "directions"
> please feel free to set me in the right direction.
> With that said, I am having problems working AO-07 and the other SSB sats.
>I can copy stations vary well but I can't seem to keep on track with them.

I can provide some direction ...
 - whether it is considered the 'right direction' remains to be seen.
I was brought up in the 'old school' before CAT and HRD assisted tuning,
so I'll describe the manual tuning mode I've used since way back.

A couple of starting points to keep in mind:
1. doppler affects both uplink and downlink, moreso the higher freq.
2. you need hear yourself, anyone calling you back will be on your downlink.
3. It is not considerate to 'sweep' your Tx around the band
   looking for yourself - better to sweep your receiver.

I'll have a table of 'un-doppler-d' transponder freqs, like this for VU-52:
    up (LSB)   dn (USB)
     ...        ...
   435.260    145.290
   435.250    145.900
   435.240    145.910
     ...        ...

As the pass starts, lets say I'll set Tx for 435.240 (LSB)...
then I'll set the Tx to CW and send a string of dits with the keyer.
I'll tune around with the Rx until I hear my dits, and zero beat them.
In otherwords, tune Rx until the pitch goes down to nothing. Then I'll
switch Tx back to LSB and whistle, and slightly adjust Rx to perfectly match
the pitch of my whistle in the headset. Now as I call CQ, I can gradually
tweak the Tx freq to keep the pitch normal so that I don't need to adj
the Rx. I try to keep the Rx coming out in the same place, so I'm only
trying to keep up with one knob (Tx)... When someone comes back, they may
drift across the band a bit, and I follow them (Rx) - assuming they are
also following themself. Then when it is my turn to Tx, I first whistle
and tweak my Tx for that zero-beat of the pitch, and start talking...

I guess I've had plenty of practice, as it comes easy for me.
If the other station is adjusting their Tx to keep a steady Rx freq,
then each of us only needs adjust the Tx freq along the way...
At least that's the way I learnt it, you know - back in the day.

Sometimes good practice for 'newbies' is to whistle to themselves,
and get some practice finding their downlink and matching the tone.

This method works with manual tuning, others may have additional suggestions.
Probably the guys using CAT have methods that better suit their needs.
The FM satellites obviously don't have the passband to waller'round in.

My radio is a Yaesu FT-736 and has the ability to lock the two VFOs once
you hit that zero-beat, but as short as the LEO passes are, I hardly ever
do that. Back in the day of AO-13, it was common to lock them and run up
and down the passband looking for other stations. Find one, unlock for a
quick zero-beat whistle, and lock it back... I do miss that bird...

I don't get on a lot, and may only get one or two contacts per pass, but
I prefer linear transponders over FM, so listen for me... I'll be the one
whistling alot. Looks like VO-52 is coming up AOS about 0340z for me.

   73 for now, let us know how it goes.   /;^)
  <- Licensed in 1976, WB5RMG = Alan Sieg * AMSAT#20554 ->
  <- http://www.somenet.net * http://wb5rmg.somenet.net ->
  <- http://www.linkedin.com/in/alansieg * My 'Day Job' ->

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