Philip, I use M2 EggBeaters, both have preamps for receive... I use no more than 10 watts and am heard fine, if and only if the sat is on a low pass (i.e. less than 15 degrees above horizon) I may use 15 to 20 watts to be heard.. 50 watts is way too much power and indicates another problem if they cannot be heard..
My 2 cents
David KK4QOE
-----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of Philip Jenkins Sent: Sunday, August 02, 2015 7:54 PM To: [email protected] Subject: [amsat-bb] Why too much uplink power is bad/eggbeater antennas on xmit
The discussion on uplink power fits right in with a conversation I had last weekend...
While I was not wearing my AMSAT badge at a hamfest on July 25, a married couple - both hams, both fairly recently licensed - recognized me from a previous hamfest when I was wearing that badge. Their question for me was to why they could hear (a) satellite(s), but no one could hear them...
The satellite in question is SO-50 (and I did take a few minutes explaining the difference between linear birds and FM-only ones).
Before the OM joined us, his YL told me that her husband doesn't want to use antennas like the Elk or Arrow, even on a tripod. I then suggested to her that he consider a fixed elevation mount, so as to only have to track the azimuth.
Then the OM showed up. He doesn't even want to consider the fixed-elevation, because he'd still have to track . I suggested he leave the tracking to a computer...still not acceptable
He then explained that they spend a lot of time in a motorhome. For his antennas now, he is using eggbeaters. On the 440 receive side, he is thankfully using a pre-amp, so he can hear adequately,
For the transmit, he is using 50 watts into an eggbeater, and still can't be heard on the satellite. He told me one recommendation he was given was to increase the xmit power to 150 watts (*I visibly shuddered*) so as to overcome the non-directionality of the eggbeater. (And I explained why too much uplink power is bad for both FM and linear sats, in terms of bandwidth and power consumption on the satellite.)
On further questioning, he knew about the PL tone to turn-on SO-50, but didn't know about the different PL to actually access the satellite on each transmission. I explained to him that it is like terrestrial repeaters; no matter how much power you run, the repeater won't "hear" you unless you transmit the PL every time.
In a follow-up email the next day, I passed on the SO-50 operating guide (PDF) from the AMSAT website, and advised him to try programming his radio with the proper PL and frequencies for adjacent memories BEFORE consdering increasing transmit power.
I really think his problem is not using PLs, rather than inadequate power levels on an omni antenna.
My question is two-fold (I still need to follow-up with him). 1) For those of you successfully using eggbeaters for the uplink (and he is adamant about not using a yagi, despite my advice that the performance will suffer quite a bit with eggbeaters), what output power do you typically use? I think 50 watts into an eggbeater is probably still too much power, considering 5 watts into an Arrow is usually enough for successful communications.
2) I know that various power levels are suggested for various gain antennas, but I'm wondering what the suggested EIRP is for successful - not ones which would hog the satellite - uplinks.
Philip N4HF _______________________________________________ Sent via [email protected]. 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