Hi David,
You are spot on, fortunately, this old dog used to manual tune all the time, so its just a matter of me going back to my original ways to doing things.
Knowing that the the LO is changing around a bit with temp makes me understand why the Doppler corrections never seemed to fit what I was hearing from the bird itself, even thought most of my operation is during Eclipse (before it emerges back into light, when the temp should be cold and fairly stable).
AO-73 is a great bird, and a pleasure to work, but I do hear people time and again saying they can never hear themselves on the downlink. All it would take is a published hint to try transmitting higher by about 8-12 KHz for example, and I think folks would have much more luck. The information is out there, in various forum posts, personal blogs, and message systems, it just hasn't been adopted by authoritative sources like funcube.org.uk, or AMSAT itself (which list the original ideal UL/DL relationships). Until then it is sort of unconfirmed rumor.
Thanks again!
73, Bob, WB4SON
On Mon, Oct 26, 2015 at 11:06 AM, David G0MRF g0mrf@aol.com wrote:
Hi Bob.
AO-73 is difficult to track using a PC as there is a fixed offset on the receive crystal oscillator together with a variation in frequency which is temperature dependent. Consequently, the ideal midband frequency when the satellite is at TCA will be different for a pass in eclipse or a pass during the illuminated part of the orbit.
As you know, it takes a bit of getting use to, but once you get the feel for it, manual tuning can get good results. I agree the published frequencies should probably include the fixed offset so people can get a little closer to the 'correct' frequencies for success.
73
David
-----Original Message----- From: Bob WB4SON@gmail.com To: George Henry ka3hsw@att.net CC: mm0kjg mm0kjg@googlemail.com; AMSAT-BB amsat-bb@amsat.org Sent: Mon, 26 Oct 2015 13:52 Subject: Re: [amsat-bb] Ao 73 problems
Hi George,
You are one of many who have said manual tuning is best, and after so many similar comments, I should probably give that a whirl.
Of course this will vary for rig and doppler, but I'd be curious to know what you find your tx frequency to be at mid pass?
The reason for asking is the published spec is
Uplink 435.150 - 435.130 MHz LSB (Inverting) Downlink 145.950 - 145.970 MHz USB
Implying that a RX of 145.960 (mid band) would have a TX of 435.140. From my tests it appears that I would actually have to transmit on 435.156 to hear myself at mid-pass. That, of course, appears to be outside of the published passband, and those published specs probably prevent anyone new to the bird from ever finding themselves.
I appreciate and data or feedback.
73, Bob, WB4SON
On Mon, Oct 26, 2015 at 12:21 AM, George Henry ka3hsw@att.net wrote:
I have found that computer tuning for AO-73
simply doesn't work... the
satellite frequency drifts enough that your up-
and downlinks won't stay in
sync for long. I leave my downlink frequency
alone as much as possible
(unless needed to chase the other guy), and
manually adjust the uplink, and
that has worked well for me.
George,
KA3HSW
----- Original Message ----- From: "mm0kjg via AMSAT-BB" < amsat-bb@amsat.org> To: amsat-bb@amsat.org Sent: Sunday, October 25,
2015 6:24 AM
Subject: [amsat-bb] Ao 73 problems
Hello all.
I
seem to have a wee problem with working Ao-73. The problem I cant work
it at
all. I am hearing people talking but when I attempt to find my
downlink
nothing heard. I have tried sending cw up and tuning downlink and
also
tuning uplink and nothing. I have set up tuning for 145.950 down and
435.150 up. Am missing something here?
I spoke to my good friend and very
good Sat operator Derrick Gm0fmw and
he also cant access it with a fairly
good antenna set-up. We are both in
Edinburgh Scotland Is this the
problem?
Please all help will be appreciated .
Thanks Kev MM0KJG
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Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings:http://www.amsat.org/mailman/listinfo/amsat-bb