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Re: Trying AO-40

HI guys,

I believe the 2836.990 conversion is still accurate, but in a quick search
I did not find a reference to it.  I suggest everyone, that is a regular
user of AO-40, to bookmark the following web address for up-to-date info:


And I have one of these handy circular calculators to help me find my
uplink frequency once I know the current MA (either from my tracking
program or the beacon telemetry).  With +/- Doppler of up to 30 KHz getting
an accurate number for the uplink can be challenging. So look at this:


Using my calculator set to mid-pass MA= 128 I get the uplink of 435.667
MHz!  The Calc even is marked MB at this freq.!  (Hint: At MA=128 Doppler
is theoretically zero!)

Small deviations from the calculator will be observed.  You must know where
your receiver is tuned (does 2401.323 show on the IF radio at 145.323 or
123.323, or do you have to add/subtract a freq correction for your convertor).

Wish it could be simpler but this is NOT that bad after the initial few times!
Ed - AL7EB

By the way, the considerate method of finding your own signal on AO-40 is:
1)  Find the beacon first and peak up your antenna.
2)  Tune your downlink (2401 MHz) receiver off from the beacon frequency by
a min of 20 KHz (preferably more so you don't step into an ongoing QSO...I
try to go to 2401.370 or higher where there is little activity up there).
3) Listen on this new freq. to be sure no QSO is in progress.
4)  Calculate your uplink for this downlink freq using the handy calculator.
5)  Set your transmitter to that freq. (keep Tracking feature off for now).
6)  Transmit some "dits" and you will likely be within close enough tuning
to hear yourself.
7)  If not then slowly tune the Tx until you do.  It should only require
tuning +/- 1-2 KHz.
8)  Lock the tracking feature on your radio if you have one.
9)  You are ready to operate "on-freq"!

This is far better way to find yourself than tuning ("ditting") thru
everyone on AO-40 while searching for the correct up link freq.  It is also
very fast and reliable!

At 01:57 PM 6/1/2003 -0400, Don Woodward wrote:
>The conversion equation I have used in the past is:
>2836.99 - S2RX = UTX
>2836.99 - 2401.323 =  435.667
>This assumes no Doppler or error/drift in the downconverter.
>I have a conversion chart at: http://kd4app.webhop.org/ao40/conversion.htm
>Don Woodward
>AMSAT 33535
>----- Original Message ----- 
>From: "Andrew Glasbrenner" <glasbrenner@mindspring.com>
>To: "Reinhard Schulze" <dc8ts@onlinehome.de>; "Jon Ogden"
>Cc: "David Rush" <david@davidarush.com>; <amsat-bb@AMSAT.Org>
>Sent: Sunday, June 01, 2003 13:43
>Subject: Re: [amsat-bb] Trying AO-40
>35 khz difference is sweeping a lot of QSOs. 435.666 gets you within 10 khz
>every time. There is no substitute for accurate information. If you don't
>know, let someone else answer, because Hardy is right, and you are not.
>73, Drew KO4MA
>----- Original Message -----
>From: "Jon Ogden" <na9d@speakeasy.net>
>To: "Reinhard Schulze" <dc8ts@onlinehome.de>
>Cc: "David Rush" <david@davidarush.com>; <amsat-bb@AMSAT.Org>
>Sent: Sunday, June 01, 2003 12:24 PM
>Subject: Re: [amsat-bb] Trying AO-40
>> On Sunday, Jun 1, 2003, at 09:23 America/Chicago, Reinhard Schulze
>> wrote:
>> > I wonder about 435.700 MHz as a corresponding uplink frequency for the
>> > beacon. For me it's abt. 435.666 MHz.
>> > On my website I have compiled some information about
>> > preparing for AO-40 from my experience.
>> >
>> > 73 de Hardy DC8TS/KC2DMA
>> 435.7 is about the theoretical uplink if you chart it out from the
>> published frequency tables.  It may be different for you due to
>> doppler, radio variations, etc.  Regardless 435.666 is still fairly
>> close to 435.7.
>> 73,
>> Jon
>> NA9D
>> -------------------------------------
>> Jon Ogden
>> NA9D (ex: KE9NA)
>> Citizen of the People's Democratic Republik of Illinois
>> Life Member: ARRL, NRA
>> Member:  AMSAT, DXCC
>> Ham Radio Webpage: http://www.qsl.net/na9d   <- Updated on 1/12/03!!!
>> Digital Photography Page:
>> http://homepage.mac.com/jogden/Photography.html

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