pcs 8015 unstable, transmitter problems

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tower block dreamin
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pcs 8015 unstable, transmitter problems

Post by radionortheast » Wed Jun 05, 2019 9:50 am

afew months I had none dc short aerial connected, blew the final transistor on both my 3000+ and 8015. I was able to get both working again, the 3000+ stopped working a week ago took me a week to find out it was loose connection to ground under the final, unforunately it nolonger shows tempreture tiny black component was burned out durring the desoldering (it measured 5.7ohms I don’t know what it was, obviously not a resistor) . I was wondering if the 2015 is the same as the 3000+, but closely looking at the pictures looks like their the same, the whole ramping up slowly is incase its connected to an amplifier.

I had been using the 8015 in the mean time but i’ve noticed it can go unstable fairly easly, slight wind hitting the aerial, less than perfect swr, on my radio nearby I started hearing it breaking throught on other frequencies. This is with it set to low power 1w, or 3w, I wouldn’t of noticed it at all but I use my radio as a white noise generator.

Theres something weird about the 8015, its always ramped up the power very slowly which is annoying, it dosen’t show reflected watts, it always reads zero. when I turn down the power to zero on my 3000+ I get nothing on my radio, but doing it with the 8015 theres still a signal there. You can still get about half a watt, if you bypass the output transistor, I was wondering if perhaps the output transistor is been over driven?, as they both use the same transistor.
with the 3000+ on low power I should be ok but if it goes wrong i’ve got no replacement, if the tempreture goes too high theres no protection..

the output transistors are pd85015 they seem use, I thought about trying to find a lower wattage output transistor for the 8015, Seems to me the problem is with the early stages. Its been years since I did anything of that nature, you could easyly swap transistors in old veronica nrg plls these things are alot different…

Albert H
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Re: pcs 8015 unstable, transmitter problems

Post by Albert H » Thu Jun 06, 2019 3:12 am

Your tiny black component could have been a base to ground choke. This is usually essential for the amplifier to have stability and useful gain.
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