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why is my amp clicking on and off during TX on high?

loosecannon

loosecannon

Sr. Member
Mar 9, 2006
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hi all, hoping to get some advice here.

i am running a texas star DX400 amp, at home, using a pyramid PS52K 50 amp power supply.
i am driving the amp with a 2000gtl that is deadkeying 2.5 watts, and swinging to maybe 20 watts PEP.

the problem is, when the amp is on high power, it will squeal, and/or start clicking from RX to TX back and forth.
if the mic gain is all the way down, sometimes it squeals, sometimes it will stay keyed.

SWR into the amp is 1.5 on high.
SWR out of the amp is 1.2 on high.

is it harmonics from the radio that is causing the amp to go into self oscillation?
the radio does have the AMC removed, (R131) but i only run the mic gain at 12 o clock max.

is it just too much for the power supply?
the supply is metered, and it doesnt seem to be the problem, the amp does.

any advice, experiences, or whatever are helpful.

amp works fine in low or med power.

thanks,
LC
 

What do you mean by clicking on and off ? Do you mean the relays are chattering ? Try and different size patch cord (jumper) between your radio and amp or add another one to the one that's already there with a barrell connector and see if the chattering stops. IM still not very sure what you mean by on and off ?
 
its not chattering.
i have experienced that before.

its like on modulation peaks it will unkey the amp temporarily.
if i speak a steady "ahhhhhh" into the mic, it will key and unkey about once a second, but not steadily. intermittantly

maybe it is just starved for current.
this is the biggest amp i have tried on the PS52k supply, and pyramid is not the greatest brand, but this amp shouldnt be pulling anymore than 40 amps should it?

its 4x2290

thanks for the interest,
LC
 
so the relays are not chattering , but they are slowly opening and closing on transmit , I think your power supply is more then enough for that amp , I've seen 50 ampers run DX500 without any problems , Did you try changing jumpers for grinnies ? other then that and not being to swavey when it comes to amps , my next guess might be a keying transistor in the box ? Texas Star will usually fix something like that for free , you would just need to send it to them after getting a RMA number from them.

I don't have the number off the top of my head , but if I come across it I'll give it to you .
 
I've had a few sent to Escondito like yours over the years and they returned fixed and still worked on 11 meters. And nether amp cost me other then shipping it to them. You just need to get the RMA number from them first.
 
Typical CB amplifier might have RF bouncing around inside the (hopefully RF-tight) cabinet and affecting the operation of the relays. Just a guess, but since it works "properly" on lower power, you might look at that. Look at the power supply also, though.

Try ferrite beads on the relay coil leads. Can't hurt. Might work.
 
i had a problem sort of like this what i had was a 500 ts on a 52 amp like the one you have and what had to do is turn the dk down on the radio to like 1 watt because what was happening was when i first keyed up it would peak the amps and shut the power supply off ...........when i first would key up my dk on the amp would shoot way up and then fall back good luck
 
loosecannon said:
thanks for the replies guys, all good stuff!
LC
Click to expand...

Check the cap from the input socket to the key circuit, there maybe a cold solder joint which might disconnect at higher input from the radio or possibly may have gone short.

I've seen cold solder joints on the relays also so you might key it up and try wiggling the relay and you may find a solder problem there.
 
Initial reaction was stray rf getting into the circuit somewhere, but...

I don't think that power supply is enough for the amp. How many watts does that amp put out...500 or so? 500/13.8 volts / .5 (efficiency for an AB biased circuit) = 72 amps . Your power supply is a 50 amp, but probably about 40 amp constant?
 

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