[amsat-bb] Problem with original AMSAT Satellite RX preamp
I have one of the Original AMSAT Broadband Satellite RX Preamps which has quit functioning. I have checked most of the components and everything looks normal except there is a large loss of signal instead gain. I suspect the Mini-Circuits MAR-07 has failed. Both Mouser and Digikey list the part as discontinued and zero stock. Is there a source for quantity 1-2 each of the part, or does the AMSAT group that builds it have the part available? Or is a substitute available? Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Finding yourself on the linear transponders
Perhaps it’s just me, but it seems like an increasing number of operators are trying to find their downlink by speaking into their mic while tuning up and down the band, often plus or minus 20-30 kHz. Not only is this disruptive to existing QSOs, it is not the most effective way to do it. My receiver has a panadapter with a 40 KHz bandwidth, and I can see these SSB signals swishing up and down, over and over. If you don’t have computer control of your frequency, set up a switch by which you can send a SHORT series of dits. Then don’t swish. Adjust your transmitter is steps of about 3 kHz. Send a burst of dits at low power and listen. If you don’t hear yourself, tune up or down. This way you will have an effective way to find yourself and you won’t interrupt other QSOs repeatedly. Once you find yourself, make sure you are not interfering with an existing QSO. Then refine your tuning until your frequency is nearly right. If you are operating CW, your done. If you are operating SSB, try holding a tone generator near your mic and adjust your transmitter or receiver until the tone on the downlink matches the tone generator. There is probably a free tone generator available for your smart phone. Better yet, try computer control of your transmitter and receiver. You can easily find an Elmer on the air if you need help. But, PLEASE. don’t swish! Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] AO-73 frequency fluctuations
Using the keps from this morning (epoch 1.066), I measured the frequency of the telemetry signal of AO-73 during a 43 deg pass at about 1648 UTC (Nov 29). This is a pass with the satellite in the sun The frequencies are the frequency “at the satellite” calculated by SatPC32 to place the center of the telemetry in the middle of my 3.0 kHz USB passband. Thus the frequency of the center “at the satellite” are 1.50 kHz higher than these. Elevation xx where the frequency is 145935.xx MHz 0 .94 5 .87 10.81 15.73 20.70 25.62 30.60 35.56 40.57 43.54 40.48 35.42 30.37 25.39 20.36 15.32 10.30 5 .27 0 .20 Thus a change of about 600 Hz over the entire pass with the frequency DECREASING. -- Using the keps from this evening (epoch 1.744), I measured the frequency of the telemetry signal of AO-73 during a 21 deg pass at about 0340 UTC (Nov 30). This is a pass with the satellite in shadow, running on batteries. The frequencies are the frequency “at the satellite” calculated by SatPC32 to place the center of the telemetry in the middle of my 3.0 kHz USB passband. Thus the frequency of the center “at the satellite” are 1.50 kHz higher than these. Elevation xx where the frequency is 145934.xx MHz 0 145933.98 5 .00 10.12 15.16 20.21 20.32 15.48 10.50 5 .65 2.5 .74 0 .76 Thus a change of about 800 Hz over the entire pass with the frequency INCREASING. However, where noted with , there were were sudden shifts in frequency up and down of 1.0 to 1.5 kHz. During this pass, the linear transponder was on, and I assume the sudden shifts of frequency noted by could have been caused by changes in total power used by the transponder. - The first pass above was during battery charging and the frequency decreased. The second pass was during battery discharging and the frequency was increasing. The sudden shifts of frequency are very obvious when you are in QSO on the transponder. It would be interesting for someone to correlate the frequency shifts with some parameter such as voltage or temperature. Ron W5RKN EM10ci ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: AO-73 keps
Using the keps from this morning (epoch 13331.102), the Doppler corrections by SatPC32 are slightly closer than yesterdays keps. I got the following frequencies from a 40 deg pass about 1739 UTC. The frequencies are the frequency “at the satellite” calculated by SatPC32 to place the center of the telemetry in the middle of my 3.0 kHz USB passband. Thus the frequency of the center “at the satellite” are 1.50 kHz higher than these. Elevation xx where the frequency is 145935.xx MHz 5 .88 10.78 15.76 20.71 25.68 30.68 35.62 40.55 35.48 30missing 25.44 20.43 15.35 10.33 5 .28 Thus a change of only about 600 Hz over the entire pass, a little better than yesterday. Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] AO-73 keps
The keps from this morning (epoch 13330.154) brings the sat LOS a little early. I was clearly hearing the telemetry down to –1.0 deg after “LOS”. AOS, of course, a little late. Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: AO-73 keps
Using the keps from this morning (epoch 13330.154), the Doppler corrections by SatPC32 are much closer than yesterdays keps. I got the following frequencies from a nearly overhead pass about 1722 UTC. The frequencies are the frequency “at the satellite” calculated by SatPC32 to place the center of the telemetry in the middle of my 3.0 kHz USB passband. Thus the frequency of the center “at the satellite” are 1.50 kHz higher than these. Elevation xx where the frequency is 145935.xx MHz 5 .90 10.85 15.80 20.75 30.68 40.65 50missing 60.59 70.52 60.50 50.49 40.47 30.41 20.37 15.34 10.29 5 .24 Thus a change of only about 660 Hz over the entire pass. Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Rapid frequency change on ARISSat pass
On the nominal 0015 UTC pass over Texas, the ARISSat-1 telemetry seemed normal but at about 4-5 minutes before LOS, the frequency of the CW marker and the BPSK telemetry envelope started dropping very rapidly. I lost track how many times I had to adjust the Doppler-corrected frequency down by 100 Hz. Then suddenly, the telemetry signal stopped. Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Rapid frequency change on ARISSat pass
Forgot to note the altitude give by the most recent keps was 175 km. Ron W5RKN From: Ronald G. Parsons Sent: Tuesday, January 03, 2012 6:27 PM To: AMSAT-BB Subject: Rapid frequency change on ARISSat pass On the nominal 0015 UTC pass over Texas, the ARISSat-1 telemetry seemed normal but at about 4-5 minutes before LOS, the frequency of the CW marker and the BPSK telemetry envelope started dropping very rapidly. I lost track how many times I had to adjust the Doppler-corrected frequency down by 100 Hz. Then suddenly, the telemetry signal stopped. Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] ARISSat-1 KURSK frames all zeros
On the just concluded pass of ARISSat, all the KURSK frames I copied were all zeros (except for the header). Is there a problem or a change? Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Has the ARISSat-1 CW-2 frequency shifted?
A couple days ago, I noticed that to get a 500 Hz signal for CW-2 (nominally 145.9190 MHz) to decode the BPSK-1000 signal, I had to change the unDoppler-shifted frequency on my USB receiver from 145.918500 MHz to 145.918280 MHz, a change of 220 Hz. This new value have been consistent over a couple days of careful watching. I don’t believe it to be an error in the keps or clock as it has been true both at the beginning and end of the pass. My receiver has been on for over a month, so unless a component changed value suddenly, Has ARISSat-1 changed, has my radio changed, or does only my hairdresser know for sure? Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: ARISSat telemetry and Doppler tuning
One thing I've discovered which makes things go more smoothly is to reduce the minimum Doppler tuning interval. I am using SatPC32 V12.8a. There are two parameters in the CAT menu -- the Speed which I changed to 5x (which is not sticky) and the minimum Doppler tuning step for SSB which I set to zero (it will be sticky if you remember to click Store). With these two changes, although the Doppler correction may drift off, it does so very smoothly, which I assume allows the decoding of the BPSK data to be more accurate. Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] ARISSat telemetry and Doppler tuning
Last evening, after having several days experience capturing ARISSat telemetry, I sat at my radio and watched carefully how SatPC32 and ARISSatTLM played together. I had settled on a tuning correction value of –540 HZ to get the CW signal to center around the CW tuning point as the Doppler correction was handled by SatPC32. The approach of the satellite seemed normal. but as the satellite passed by, I noticed the CW signal average “position” to be creeping upward, needing a reduction of the tuning correction by about 40 Hz to –500 Hz. This lasted for a couple minutes and then the CW signal started creeping down and I had to go back to my –540 Hz value. The first explanation I could think of is that the Doppler correction computed by SatPC32 from my position and the keps was in error. But of course, it could have been a change in my radio (unlikely as it had been on for hours) or a change in the frequency of the CW signal from the satellite. I’ll keep watching this and wonder if others have noticed something similar. Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Certificate for receiving BPSK-1000 telemetry
The ARISSat web site shows how to get a Reception Certificate for Voice ID, Voice Telemetry, and SSTV. I have screen shots of the BPSK-1000 reception and CW. How does one claim a certificate for BPSK-1000 reception? Ron W5RKN ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Full Doppler Tuning
My July/August 2010 issue of The AMSAT Journal arrived today and I was pleased to see the article by Alan Biddle on Doppler Tuning. This has long been a pet project of mine since Paul Williamson, KB5MU, published his article The One True Rule for Doppler Tuning in the OSCAR Satellite Report, January 1994 and my article A Recommendation for Doppler Tuning in the March/April 1996 issue of The AMSAT Journal. I was especially pleased by Alan's call for satellite tracking programs that control your transmitter and receiver to display the frequencies at the satellite. This should be very easy for the developers of the software to do. For example, in SATPC32 (an ad for which appears on the last page of Alan's article), the frequencies at the satellite are almost displayed now. In the center of the window, just below the menu bar, are displayed the Receive and Transmit frequencies (at your location) and just below these are the Doppler correction values from the frequencies at the satellite. Algebraically subtracting the lower (Doppler correction) value from the upper (your site frequency) values yields the frequency at the satellite. It would seen to me that the program should display the frequency at the satellite as the frequency of your receiver and transmitter are most likely already displayed on your rig. How about it, you software developers? At least give your users the option of which value to display in your window. As an aside, speaking of Doppler shifts, I (along with K5EWS and others) are currently working on a method of tracking model rocket flights using an inexpensive UHF transmitter (925 MHz CW in my test case) in the rocket and, using several receiver sites, analyze the Doppler shift of the transmitted signal and use the mathematics of Trilateration to determine the location of the rocket in 3-space. Our first full scale test is this coming weekend. Ron Parsons W5RKN ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: IC-910H low audio problem.
I discovered this with my 910H. If you compare the schematic with an older Icom transceiver, say the IC-756, you will notice that the voltage divider on pin 8 decreases the audio on that pin by a factor of about 50 from the IC-756! I thought of two cures: 1. Modify the radio by replacing the offending resistor. 2. Modify my headset by bringing the line that would go to pin 8 outside the mic connector and run it to a 1/4 phone plug. I chose 2. I plug the phone plug into the nearby headphone jack when I use the headset, or pull it out to use the speaker. Works on both my 910 and 756. I was told by a person at Heil that Icom made that change to better use a TNC with the mic connector on the 910. Ron W5RKN Date: Tue, 9 Jun 2009 05:21:35 +0300 From: Kostas Ioannidis kostas.ioanni...@gmail.com Subject: [amsat-bb] IC-910H low audio problem. To: AMSAT-BB@amsat.org Message-ID: 6cd5903a0906081921k5cb111e0j945fc7b09e7d...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 According to the IC-910H manual, pin number 8 at the mic connector is audio output (which varies according to af control). I connected a pair of headphones at the pin but the audio is way to low and cannot be used for listening. Is it normal? I thought that it was designed for this purpose. Am I missing something in the menus? Thanks in advance! 73 de SW1IXP, Kostas Ioannidis ___ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
