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Author Topic: SSB transmit frequency management  (Read 7024 times)
K7ZRZ
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Posts: 279




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« on: February 19, 2013, 10:50:22 AM »

From a beginner....   what is the basic, PRACTICAL, requirement for controlling my transmit frequency for doppler shift while working SSB through Hamsat VO-52??

For an operator who has radios which are NOT capable of being controlled by a computer program, what might be some tips for making SSB contacts and not mess things up for others that are also trying in earnest to make contacts at the same time?  I happen to have two radios (IC-7000 and an FT-817ND that can be controlled... just asking the above out of curiosity.

I've only made two contacts so far over the FM SO-50 satellite, and understand the basics of that pretty well. (What a fun trip).  However, the information I have been able to gather on SSB satellite operation is sketchy and scattered.  And also that situation is complicated with AmSat site being so inaccessable.

Thanks,
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Brian K7ZRZ
W5PFG
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« Reply #1 on: February 19, 2013, 12:32:34 PM »

From a beginner....   what is the basic, PRACTICAL, requirement for controlling my transmit frequency for doppler shift while working SSB through Hamsat VO-52??

For an operator who has radios which are NOT capable of being controlled by a computer program, what might be some tips for making SSB contacts and not mess things up for others that are also trying in earnest to make contacts at the same time?  I happen to have two radios (IC-7000 and an FT-817ND that can be controlled... just asking the above out of curiosity.

Often, I use two radios for working the satellites. 

The rule of thumb on VO-52 is to find a downlink frequency on VHF and stick to it, moving only your uplink on UHF.  You will drift a little, but not much.   Passes are so short anyway.  VO-52 takes a little practice but once you have got it down, it's the easiest to hear.

Many people use computer control... But not ALL.  I do not.  Generally you adjust Doppler on the highest frequency where there is more impact. 

If you want to try working VO-52 (or FO-29) tonight, shoot me an email to my callsign at arrl dot net.

73
Clayton
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K7ZRZ
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Posts: 279




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« Reply #2 on: February 19, 2013, 01:43:19 PM »

Thanks for the reply, Clayton. Very good information and better than I was thinking.  I do have the two radios, but not setup for SSB work quite yet. I need to devise some antenna scheme (other than the handheld Arrow I have now) for that. I'll keep you in mind for another time of trial and maybe to answer some other question about it all if something comes up.

Thanks again, I deeply appreciate your time.
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Brian K7ZRZ
W4HIJ
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Posts: 367




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« Reply #3 on: February 19, 2013, 04:52:22 PM »

My experience back in the days when I had my TS-2000 was that computer control wasn't all that great unless BOTH stations happened to be using it.
Michael, W4HIJ
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WD9EWK
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« Reply #4 on: February 20, 2013, 10:40:13 AM »

From a beginner....   what is the basic, PRACTICAL, requirement for controlling my transmit frequency for doppler shift while working SSB through Hamsat VO-52??

For an operator who has radios which are NOT capable of being controlled by a computer program, what might be some tips for making SSB contacts and not mess things up for others that are also trying in earnest to make contacts at the same time?  I happen to have two radios (IC-7000 and an FT-817ND that can be controlled... just asking the above out of curiosity.

I've only made two contacts so far over the FM SO-50 satellite, and understand the basics of that pretty well. (What a fun trip).  However, the information I have been able to gather on SSB satellite operation is sketchy and scattered.  And also that situation is complicated with AmSat site being so inaccessable.

Thanks,

The advice W5PFG offered, about using a fixed (more or less) downlink frequency and adjusting your uplink frequency is also valid for AO-7.  For FO-29, with a 2m uplink and 70cm downlink, try to keep your uplink frequency fixed and just follow the downlink.  This would be the so-called "One True Rule", making adjustments on the higher of the two frequencies, where the Doppler effect is greater, if you are not using computer control for your radio(s). 

AMSAT's web site is in the process of being rebuilt, and - even on the old site - didn't have a lot of information for getting started on the SSB satellites.  I've worked those satellites using a two-radio setup (transmit with an FT-817ND, receive with either another FT-817ND or some radio with an all-mode receiver at 2m/70cm like the Kenwood TH-F6A HT, Icom IC-R20 receiver, etc.) and a handheld antenna for several years.  I have some YouTube videos where I'm working SSB via satellite at:

http://youtube.com/va7ewk

and would be happy to go back and forth with you on getting set up to making SSB satellite contacts - either through this forum, or directly via e-mail.

Good luck and 73!
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Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
K7WDO
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Posts: 20




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« Reply #5 on: February 21, 2013, 06:53:18 PM »

I run two radios full manual and here's how I learned it:

Start with CW.  Even if you don't know Morse or want to work SSB, the doppler correction is the same either way.  And for a beginner, it's a lot easier for your ear to focus on a carrier tone than it is to listen for yourself on voice.  You can hear the pitch change with the doppler and if it sounds distorted, you're probably putting too much power in to the transponder. 

Most of the activity on the linear birds is focused around the middle of the passband.  If you tune about 10 kHz in from the top or bottom of the band, it's usually a nice empty space to practice in without needing to worry about drifting in to anyone if you get it wrong.  In the case of VO-52, 435.270 MHz will usually drop you in around 145.880 MHz on the downlink.  Start sending dits and adjust your downlink frequency until you find your signal.  From there, keep sending dits but now adjust your uplink frequency instead to keep the pitch constant.  Once you get the hang of it on CW, switch your transmitter to LSB and give SSB a try.  Receive will always be USB.

Hope this helps and have fun!
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K7ZRZ
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Posts: 279




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« Reply #6 on: February 22, 2013, 10:07:23 AM »

Thanks for the responses. I've read them and am pondering my next efforts, which are to get some kind of MOUNTED antenna setup. It's going to take a while before I arrive at SSB capability, and in the mean time, I have the FM satellite operations that I can do right now. Sure hope it quits raining out here on the Oregon Coast.
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Brian K7ZRZ
NO9E
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« Reply #7 on: March 13, 2013, 08:12:43 AM »

Would Kenwood th-f6a be good enough for receive? I have IC-7000 for transmit.
Ignacy, NO9E
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KO4MA
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Posts: 120




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« Reply #8 on: March 14, 2013, 12:43:19 PM »

Would Kenwood th-f6a be good enough for receive? I have IC-7000 for transmit.
Ignacy, NO9E

Yes, with some practice. The SSB filters are very wide. I've done it with the F6 and an 817, and I think Patrick WD9EWK has as well.
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N8HM
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Posts: 87




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« Reply #9 on: March 15, 2013, 07:40:17 AM »

Would Kenwood th-f6a be good enough for receive? I have IC-7000 for transmit.
Ignacy, NO9E

Yes, with some practice. The SSB filters are very wide. I've done it with the F6 and an 817, and I think Patrick WD9EWK has as well.

I've made one QSO on VO-52 with a TH-F6A and an FT-817. I have to get out and try it more often.
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WD9EWK
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« Reply #10 on: March 15, 2013, 08:49:49 AM »

Would Kenwood th-f6a be good enough for receive? I have IC-7000 for transmit.
Ignacy, NO9E

I have used a TH-F6A for SSB satellite work, as a receiver while transmitting with an FT-817.  As has been mentioned in this thread, it is OK - but not great.  I have had my best luck with it on VO-52 and its stronger downlink.  It hasn't worked as well for me on FO-29 or AO-7 (mode B - haven't tried it on the 10m mode A downlink), mainly on higher passes where the downlinks are a little stronger.  Since its receiver has a wide front-end, strong adjacent signals will be a problem - even strong adjacent signals coming through the transponders. 

When using the TH-F6A, it is probably best to set the VFO with the all-mode receiver (I think it is VFO B) to tune in the smallest possible steps for SSB, 33 Hz.  Its tuning steps aren't as fine as your IC-7000 in SSB or other radios like FT-817s and FT-857s to name a couple of examples, but 33 Hz should be good enough to tune in signals to have them sound intelligible.  The TH-F6A's receiver is not as sensitive as other radios like those mentioned previously, so don't expect to hear VO-52 when it is just above the horizon.  With my Elk antenna, I usually start to hear voices clearly when VO-52 is at least 8 to 10 degrees above the horizon. 

The TH-F6A is a good backup radio for my portable satellite station.  I can use it on FM satellites, as an all-mode receiver, and - one day, in the future - as a chirpy CW transmitter by keying the HT's PTT.  Good luck and 73!

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Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
KQ6EA
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« Reply #11 on: March 23, 2013, 01:53:16 PM »

Patrick, have you tried using a preamp with that setup?

Seems to me if one radio is receive only, a simple preamp could help.

Jim
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WD9EWK
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« Reply #12 on: March 23, 2013, 03:17:50 PM »

Patrick, have you tried using a preamp with that setup?

Seems to me if one radio is receive only, a simple preamp could help.

I have not tried a preamp with the TH-F6A.  Since it's not my primary receiver for satellite work, I have not worried about that radio too much.  I ordered the broadband preamp from AMSAT, but haven't had the time to try it out.  One of the many things on the radio to-do list......

73!
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Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
KQ6EA
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« Reply #13 on: March 23, 2013, 03:37:09 PM »

OK...just curious.

I just bought a bunch of MiniCircuits MAR06 and MAR-7 MMIC's to play with.

I'm thinking of making a couple of receive-only preamps, and see how well they perform on the discone I use for my scanners.
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