... >> ... what is essential for a successful and pleasant satellite operation, YOU NEED A PREAMP!
One thing that I have shown to about a hundred audiences LIVE as I work passes in front of them is there is absolutely NO NEED to spend money on pre-amp to successfully work the FM LEOs. AO-27 and SO-50 are received wonderfully with just improved antennas on handheld radios/scanners.
If you cannot hear '27 and '50 and the ISS - nor worked '51 and heard ARISSat-1 when they were available - with just a "better" antenna (suggestions on the ANTENNAS page at work-sat.com), then something is wrong with your setup.
Might a pre-amp be on one's list as a future purchase to work other birds? Quite possibly.
Clint Bradford, K6LCS http://www.work-sat.com
... what is essential for a successful and pleasant satellite operation, YOU NEED A PREAMP!
Op 21-1-2012 19:36, Clint Bradford schreef:
...>> ... what is essential for a successful and pleasant satellite operation, YOU NEED A PREAMP!
One thing that I have shown to about a hundred audiences LIVE as I work passes in front of them is there is absolutely NO NEED to spend money on pre-amp to successfully work the FM LEOs. AO-27 and SO-50 are received wonderfully with just improved antennas on handheld radios/scanners.
If you cannot hear '27 and '50 and the ISS - nor worked '51 and heard ARISSat-1 when they were available - with just a "better" antenna (suggestions on the ANTENNAS page at work-sat.com), then something is wrong with your setup.
Might a pre-amp be on one's list as a future purchase to work other birds? Quite possibly.
Good point, a preamp is to cancel out the cable losses, anymore and you are just boosting the background noise and not improving the reception. So if your cable is very short there is not point in using a preamp.
I even dare to say that you can have more succes using a portable setup then a fixed instalation with preamps and elevation rotors because you can adjust polarisation, theoreticly this can give a gain upto 30 dB, in practice somewhere between 3 and 9 dB.
73 Andre PE1RDW
Hi Andre!
Good point, a preamp is to cancel out the cable losses, anymore and you are just boosting the background noise and not improving the reception. So if your cable is very short there is not point in using a preamp.
I have never used a preamp when working satellites. If your station - radio(s), antenna(s), and feedline - are good enough, you may not need to invest in preamps.
I even dare to say that you can have more succes using a portable setup then a fixed instalation with preamps and elevation rotors because you can adjust polarisation, theoreticly this can give a gain upto 30 dB, in practice somewhere between 3 and 9 dB.
Very true! I'm working with portable setups, even from my back yard like I showed in the videos I posted earlier today, and do well without preamps. I use short RG58 coax runs - 10 feet (3m) from antenna to radio or diplexer, and 3 feet (1m) from diplexer to radios if I am working SSB/CW. Modifying K4FEG's statement to "YOU *MAY* NEED A PREAMP" would be more accurate.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/
----- Original Message ----- From: "Andre" [email protected] To: [email protected] Sent: Saturday, January 21, 2012 8:12 PM Subject: [amsat-bb] Re: Thanks for all the ...
Good point, a preamp is to cancel out the cable losses, anymore and you are just boosting the background noise and not improving the reception. So if your cable is very short there is not point in using a preamp.
73 Andre PE1RDW
Hi Andre, PE1RDW
It depends on the noise figure NF of your receiver. Lets suppose the NF of your commercial receiver is as usually in the order of 6 dB, then a preamplifier with a NF = 0.5 dB and 15 to 20 dB gain will improuve your (S+N)/N ratio even if the lenght of your coax cable between the antenna and receiver is very short.
73" de
i8CVS Domenico
Op 21-1-2012 22:06, i8cvs schreef:
----- Original Message ----- From: "Andre"[email protected] To:[email protected] Sent: Saturday, January 21, 2012 8:12 PM Subject: [amsat-bb] Re: Thanks for all the ...
Good point, a preamp is to cancel out the cable losses, anymore and you are just boosting the background noise and not improving the reception. So if your cable is very short there is not point in using a preamp.
73 Andre PE1RDW
Hi Andre, PE1RDW
It depends on the noise figure NF of your receiver. Lets suppose the NF of your commercial receiver is as usually in the order of 6 dB, then a preamplifier with a NF = 0.5 dB and 15 to 20 dB gain will improuve your (S+N)/N ratio even if the lenght of your coax cable between the antenna and receiver is very short.
73" de
i8CVS Domenico
true you can add a 5,5 dB improvement that way but you are talking EME class LNA, about 60 usd per dB is far more then most hams are willing to pay. a more reasonable priced preamp is more likely to be around 1.5 dB NF and would probably cost around 35 usd per dB improvement. However you still run the risk over overloading your reciever frontend with strong signals because you are not only boosting the satelite by 15 to 20 dB but also the athmospheric noise and other inband signals while you only needed 6 dB to overcome the NF of the reciever. by the way my ts790 is measured by DJ5IR at 4.5 dB NF so a typical preamp would only improve by 3 dB at the cost of lowering my IP3 from -14.5 dBm to -29.5 dBm, granted not everyone would do a portable opperation with a ts790 but I do. a more typical portable reciever is probably a ft817 and is measured at 5.4 dB NF by DK2DB.
http://www.df9ic.de/tech/trxtest/trxtest.html
BTW I know that the real IP3 stays the same but the offending signals are boosted giving a virtual worsening of the IP3 73 Andre PE1RDW
participants (4)
-
Andre -
Clint Bradford -
i8cvs -
Patrick STODDARD (WD9EWK/VA7EWK)