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