I've been trying to get my receive setup going the last few days but I'm having horrible results. I have my 11 element 70cm "cheap yagi" back up on the mast and my homebrew SaebrTrack and OR-360 AZ/EL TV rotator system interfaced to SatPC32. I have an ARR preamp mounted at the mast fed with a seperate 12VDC feed and about a 40 foot run of JEFA brand LMR 400. Once I get into the shack there is a bit of patchwork to the cables. I'm using a Yaesu VX3 to receive and due to the SMA connector on the HT and not wanting to strain it I have a 4 foot adapter cable of LMR 100 that goes from an SMA to a SO-239. I then have to use a short length of coax with a PL-259 to N male to mate up with a N barrel connector connected to my LMR 400 coming from outside. Now obviously, I know this isn't optimum and eats up valuable RF and I intend to change it ASAP but I'm hearing absolutely nothing on AO-51 passes. Not even the hint of signals. I'm thinking with that preamp in the line I should at lest hear something discernible besides noise regardless of the patchwork of cables. Am I off base in thinking this? I did catch just a bit of discernible signal off SO-50 last night but it was almost overhead. I'm not a beginner at this but I'm frustrated. Perhaps I'm putting too much faith in the preamp to push the signals through my hodgepodge of adapters and cables? Any thoughts are appreciated. 73, Michael, W4HIJ
Do you hear a noise increase when you power up the preamp? If not, are you sure you are getting power to it? Can you hear terrestrial repeaters, and does the signal change when you cycle the preamp power?
Check your ins and outs on the preamp to make sure they didn't get reversed. Same thing for any diplexer you may be using as a high pass filter.
More of the obvious...sure you are tracking correctly, and at the right time?
I wouldn't suspect any of the cabling or adapters other than one being flat out broken. The preamp should easily overcome any shortcomings of the cable you've described.
73, Drew KO4MA
I concur with what Drew states here. I am presently using (not by choice) a minimum setup with a 1/4 wave 2 meter homebrew groundplane for 70cm reception. I have an in-shack pre-amp that I use when I get serious in working AO-71 but I hear it rather well above 20 degrees without the preamp. I am limited to about 20 degrees or higher due to using the ground plane and a Ringo Ranger II for the two meter up link. Above 20 degrees the ground plan works well but the Ringo begins to lose signal due to radiation angle.
I recommend following Drew's suggestion and also insure that your array is pointed correctly. An 11 element array can be narrow enough to easily null out the signal if you are not in the 15 - 20 degrees beam width.
Reid, W4UPD
Andrew Glasbrenner wrote:
Do you hear a noise increase when you power up the preamp? If not, are you sure you are getting power to it? Can you hear terrestrial repeaters, and does the signal change when you cycle the preamp power?
Check your ins and outs on the preamp to make sure they didn't get reversed. Same thing for any diplexer you may be using as a high pass filter.
More of the obvious...sure you are tracking correctly, and at the right time?
I wouldn't suspect any of the cabling or adapters other than one being flat out broken. The preamp should easily overcome any shortcomings of the cable you've described.
73, Drew KO4MA
Andrew, I definitely can heart an increase in noise when I power up the preamp and also see an S-meter response. Unfortunately I have absolutely no terrestrial repeaters within my range on 70cm. I've never been able to get into one even back in the days when I had my TS-2000X. Never been able to hear them either. Checked the preamp cables to make sure they weren't backwards also. In reference to some questions from others I've had, I am compensating for doppler on receive and I've checked all my cables except for the 40 foot piece of LMR 400 for open or short with an ohmmeter. Just for giggles I decided to see if I could copy NOAA weather on 162 Mhz band and I can. Don't know if that means anything. I will check my antenna pointing. Getting an accurate fix on true north has sort of been my achilles heel before but I've managed.There is not that much declination here. When I did happen to pick up the brief SO-50 transmission last night the rotator was making a fairly large change in Azimuth though. I may just whip up a quick little groundplane to give me a baseline as someone suggested also. Thanks for all the responses I've gotten so far. Michael Andrew Glasbrenner wrote:
Do you hear a noise increase when you power up the preamp? If not, are you sure you are getting power to it? Can you hear terrestrial repeaters, and does the signal change when you cycle the preamp power?
Check your ins and outs on the preamp to make sure they didn't get reversed. Same thing for any diplexer you may be using as a high pass filter.
More of the obvious...sure you are tracking correctly, and at the right time?
I wouldn't suspect any of the cabling or adapters other than one being flat out broken. The preamp should easily overcome any shortcomings of the cable you've described.
73, Drew KO4MA
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Do you have a 70 cm source of any type that you can use downrange to prove that the system is working? That is, all together as a complete system. If you can drive the source away until it is demonstrably weakening, then you can test the beam pattern, etc. If the preamp front end is hooked to a dummy load (non functioning antenna system in front of it), then the noise from the dummy load will increase. You need an external source.
Bob
Michael Tondee wrote:
Andrew, I definitely can heart an increase in noise when I power up the preamp and also see an S-meter response. Unfortunately I have absolutely no terrestrial repeaters within my range on 70cm. I've never been able to get into one even back in the days when I had my TS-2000X. Never been able to hear them either. Checked the preamp cables to make sure they weren't backwards also. In reference to some questions from others I've had, I am compensating for doppler on receive and I've checked all my cables except for the 40 foot piece of LMR 400 for open or short with an ohmmeter. Just for giggles I decided to see if I could copy NOAA weather on 162 Mhz band and I can. Don't know if that means anything. I will check my antenna pointing. Getting an accurate fix on true north has sort of been my achilles heel before but I've managed.There is not that much declination here. When I did happen to pick up the brief SO-50 transmission last night the rotator was making a fairly large change in Azimuth though. I may just whip up a quick little groundplane to give me a baseline as someone suggested also. Thanks for all the responses I've gotten so far. Michael
On Sun, Nov 29, 2009 at 8:02 PM, Michael Tondee mat_62@netcommander.com wrote:
I've been trying to get my receive setup going the last few days but I'm having horrible results. I have my 11 element 70cm "cheap yagi" back up on the mast and my homebrew SaebrTrack and OR-360 AZ/EL TV rotator system interfaced to SatPC32. I have an ARR preamp mounted at the mast fed with a seperate 12VDC feed and about a 40 foot run of JEFA brand LMR 400. Once I get into the shack there is a bit of patchwork to the cables. I'm using a Yaesu VX3 to receive and due to the SMA connector on the HT and not wanting to strain it I have a 4 foot adapter cable of LMR 100 that goes from an SMA to a SO-239. I then have to use a short length of coax with a PL-259 to N male to mate up with a N barrel connector connected to my LMR 400 coming from outside. Now obviously, I know this isn't optimum and eats up valuable RF and I intend to change it ASAP but I'm hearing absolutely nothing on AO-51 passes. Not even the hint of signals. I'm thinking with that preamp in the line I should at lest hear something discernible besides noise regardless of the patchwork of cables. Am I off base in thinking this? I did catch just a bit of discernible signal off SO-50 last night but it was almost overhead. I'm not a beginner at this but I'm frustrated. Perhaps I'm putting too much faith in the preamp to push the signals through my hodgepodge of adapters and cables? Any thoughts are appreciated. 73, Michael, W4HIJ
Michael --
I think something is quite amiss here, perhaps a connector is bad or a bad joint in one of the cables. I bet a couple of hours with a volt-ohmmeter will find the guilty party. Alternatively, you could be in a bad noise situation.
By way of comparison, because of my digital project right now I have a very minimal station, with a 70cm vertical antenna soldered directly onto a N-connector. About 10' of LMR400 goes to the preamp, which then has another 100' of cable to my FT-817. AO-51 is not great copy, but I know it is there. Similarly, all the usual cubesats in CW mode, and SEEDS (CO-66) with its fine FM signal of cheering Japanese school-children.
(Actually, this got me thinking that SEEDS would make a pretty good way of evaluating two side-by-side receiving systems. Pass the resulting wav files through a SSTV decoder, and the one with the better picture wins!)
You might consider making a very simple vertical antenna, attaching it to one end of the preamp with a very small patch cord between it and the radio, and using that as a kind of baseline.
73, Bruce
Michael Tondee wrote:
I've been trying to get my receive setup going the last few days but I'm having horrible results. I have my 11 element 70cm "cheap yagi" back up on the mast and my homebrew SaebrTrack and OR-360 AZ/EL TV rotator system interfaced to SatPC32
Simplify. An 11-element yagi is very very pointy. Everything would need to be absolutely bob on to even be looking *near* the satellite.
Make yourself a K5OE handi-tenna - nice little three-element Yagi, great for portable operation. Work out where the satellite will "rise" and "set" and when, and tune manually for Doppler. Wait for a good high pass, and start about 10kHz high. Most FM radios tune in a minimum of 5kHz steps, so you've got only a couple of "notches" to try. The little three-element Yagi has a very broad beam, so you don't have to be *too* accurate.
Gordon MM0YEQ
participants (6)
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Andrew Glasbrenner -
Bob McGwier -
Bruce Robertson -
Gordon JC Pearce -
Michael Tondee -
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