On Feb 18 2011, zach hillerson wrote:
I purchased a Yaesu 847 for both satellite and HF work. Since this is my
1st base-style transceiver I am now in need of a power supply. I was
originally considering the Astron RS35M and am curious if linear or
switching is the proper choice? Is there a Amsat BB favorite between
switching and linear?
Thanks for any help!
Zach
N4ERZ
Zach:
I've had my FT-847 for many years, and have used it both for satellites and
VHF/UHF terrestrial work. (Very little HF, but some).
It has never complained about any properly working power supply it's been
hooked to. These include an Astron 20 amp linear PS, an Astron 60 amp
linear, an Astron 35 amp switcher, car battery plus vehicle alternator, and
others when I've brought it out to Field day. Runs perfectly with any of
them.
In general, more power is better, because these amp suckers seem to
multiply. My first PS, the 20 amp linear, worked fine with the FT-847, but
when I added a linear amplifier for the 144-148 MHz band, the combined draw
was too much. I've NEVER managed to draw more power than the 60 amp linear
can provide, but it is an enormous pain (literally and figuratively) to
pull it off its usual resting place in the shack and carry it up two
flights of stairs to load into my SUV to haul out to Field Day. The 35 amp
switcher has done a fine job for me, and the difference in weight is
incredible, at least to a rickety old guy with worn out knees, like yours
truly.
In fact, my FT-847 has NEVER refused to work for me, except for the time I
set it up in a tent trailer for Field Day on a Friday afternoon, and a big
wind storm came through overnight. When I arrived Saturday morning to
complete final setup and get ready to operate, I found that the tent
trailer was lying on its roof, with the FT-847's face planted in the ground
and its back panel holding up one end of the tent trailer. At that point,
the big knob on the front would not turn, but who could blame it? And best
of all, the repairs cost $0.00! After Field Day was over, I brought it
home, started a careful disassembly of the front panel, and discovered that
the reason that the tuning knob wouldn't turn was because the steel
sub-chassis onto which it was bolted had bent from the weight of the
trailer on top of the radio. Some carefully-placed whacks with a big hammer
fixed that. Put it back together and it's worked like a champ ever since.
(I also used some toothpaste to polish up the scratches on the front face
of the tuning knob, and you'd never know it had been treated so cruelly!)
In short, the 35 amp Astron (either linear or switching) will be plenty
strong enough and reliable enough to power an FT-847 and a typical VHF/UHF
amplifier, with power left over to run more small station equipment.
73 de W0JT
___
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
