Power Supply Problems

[1 ADAM 12]

I have a Pyramid PS14KX power supply that I use to operate a Yaesu FT2900 mobile 2-meter radio (setup as a base station). The power supply works great as long as the radio is operating at 25 watts or less. When I operate the radio in the 75 watt transmit mode and key the mic, the radio shuts off and immediately restarts (the power supply continues to run). The power supply does not get hot. The Yaesu manual states that this radio will draw 11 amps. This power supply operates at 12 amps constant and 14 amps surge. The power supply is brand new. What is the problem?

['Doc]

Sounds like your radio is telling you that there's not enough current and shuts down.
- 'Doc

[MDYoungblood]

Sounds like the final circuit shutting the radio down, check the antenna and connections. Try the high mode into a dummyload and see if it does the same thing. If the radio was drawing more than the PS could handle than the PS would shut down. 'Doc has a good point too, look to see what the fuse is in the PS, it shouldn't be any larger than the rating and while you are at it look at the radios fuse to, same thing applies there. I am not familar with the Pyramid PS's but have been told their rating's are pardon the pun, "overrated".

3's

Greg

[Savoirfaire]

Try on the lower power settings and make sure the power supply stays on then.

If so, then you are over drawing the power supply.

The only Yaesu FT2900 I found on the web has an (FT2900 R).

It says on the web 13.8 VDC at 14 amps.

This is probably the problem as you are very close to too much power and at times it will shut down on high power.

Looks like other power settings can be used until you can get things straightened out.

73, Frank 10 X-Ray 47

[231]

I agree with everyone else. You are running the power supply at it's 'marketing limit.' You always want a little more fudge room when sizing a power supply...even if you have to run on batteries a little longer in order to afford one. Turning down the transmit power a tad will likely solve the problem. Besides, its not likely anyone (but you) will notice any difference whatsoever between 50w and 75w most all of the time (especially on repeaters).

There are a couple of other possibilities...but I believe the one already stated is the likely culprit. Another possibility is the wiring connection to the power supply might need re-doing. Double check they are soldered well and making good contact. Yet another possibility is a short in the antenna system somewhere failing at more than say 50w. I've had it happen on my Icom IC-7000 before when a brand new barrel connector (SO-239 x SO-239) would short at more than 50w. Under that it was fine, but it would cause the transceiver into a re-boot. I was using it on a portable dipole set up in the mountains, and thankfully had another with me...but it was a pain trying to determine where the problem was. In any event, if you've checked or replaced everything else above, then it's time to start looking at coax, antenna connections, the works.

Hope that helps a little more.

231

[1 ADAM 12]

Thanks for all the replies. I have a confession to make. The manual for my radio lied to me a little. In one section of the manual, it states that the operator needs a power supply that will produce at least 11 amps. Then in another section, the manual states that the radio requires 15 amps to be operable on high power (75 watts). I currently operate the radio at only 25 watts. The power supply seems to work great at this setting. Just simply need to get a power supply that has more amps. Thanks again.