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Re: New FT-847, Help with doppler shift please



Hi Rick.

I've tried successfully the same configuration on FO20 (FT847 and Arrow
antenna).

You might want to check my page www.btinternet.com/~hlong/using_the_ft.htm
on configuring and using your FT-847 on transponder birds.

I use manual doppler compensation. I've tried (not very hard I hasten to
add) using computer correction on the 847, but I found it more trouble than
it was worth. More often than not the other station is using manual
compensation, so a bit of technique has to be learned. The general rule of
thumb was 'keep the lower frequency fixed', but on relatively quiet birds
like FO20, I've found it's not always adhered to. A frequent small
adjustment with the sub tune and occasionally the main tune keeps me on
frequency.

I'm very envious about your AO10 operation even though it was curtailed.
Never manged to work it myself! I suppose I must go out portable again with
that Arrow antenna to see what I can do!

73, Howard G6LVB

----- Original Message -----
From: "Rick Allnutt" <ws8g@hotmail.com>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, June 12, 2000 9:13 PM
Subject: [amsat-bb] New FT-847, Help with doppler shift please


> BBs,
>
> I have been trying to get on a satellite for several years.  At
Hamvention,
> I bought an Arrow and was on the FM birds within a week.  That got me
> excited, and I decided to jump into the deep water.
>
> I got an FT-847 from the UPS on Friday and made several FM UO-14
> and AO-27 contacts on Saturday AM using the Arrow
> Antenna on a camera tripod without the duplexer, of
> course.  I listened for FO-20 in vain.  On Sunday, I
> made a number of contacts on the FM Birds and heard
> myself and traffic on FO-20 and FO-29.  I even heard
> someone call me back, but lost the signal before I
> could complete the contact.
>
> For grins, having about 10 minutes before I had to go
> to an open-house, I set up the arrow antenna toward a
> relatively low pass of AO-10.  The satellite had
> passed North America and was heading out, but still
> about 45 degrees above the horizon.  I heard several
> people making contacts, but was pulled (kicking and
> screaming) into the car to fulfill my social
> obligations before I could try to make a transmission.
>
> QUESTIONS:
>
> I have an effective technique down for changing the
> freqs on the FM birds for doppler shift, but have no
> good technique for the SSB sats yet.  A little help
> here would be appreciated.  Here are my setup and my
> questions:
>
> I have the main tuning dial set to transmit freq and
> the sub freq to receive.  (I have the two frequencies
> set to track each other inverted, and the
> sub frequency can be changed alone to deal with
> doppler effect.)
>
> I have been starting at the middle of the pass band
> and searching for my signal by whistling.  If I
> remember right, I have to tune up on the receive
> during the early part of the pass from the simple
> inverted frequency and that receive frequency drops as
> the pass continues...  Seems like if I have the
> Transmit set to 145.950 and the receive to 4XX.850 I
> have to increase the receive to about 4XX.855 or
> 4XX.860.  The receive then drops to about .010 below
> .850 (4XX.840) by the end of the pass. Is this about
> right?
>
> Can the numbers reported as doppler shift on the
> tracking programs be used to predict this frequency
> shift directly?  Is that useful, or does one just get used to changing the
> frequency to compensate for doppler?
>
> A newbie trying to learn.  (And get it right the first time.),
>
> 73s de WS8G (Rick)
> ________________________________________________________________________
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