Well, well, what should I say.......it´s unbelieveable.

I thought, before I replace everything in the rectifier unit, I will measure the DC voltage after the rectifier unit. And what should I say - 3100 VDC.

But the HV-meter on the front tells me only 300V. So now I´m sure everything is working well in the PA, except the meter.
On the way from the high voltage, there are three resistors. I´ve measured everyone before, but NOT out from the board. And this was my fault. The 1.5MOhm resistor is open. So the meter can´t tell me the truth.

I will replace only one resistor, and this was it. The PA is working well, and everything on the display also. I´ve learned very much about the function of the PA and the fault-finding in it. Also learned much about the handling of high voltage.

I have to say a big "THANKS" to everyone here in the forum who helped finding the right way.

Hope to hear from you, maybe on the bands.

73 es 55 de DH1OK

Hi,

well after two days here, now i´ve got a bit of time for the pa.

First i have to say sorry, of course the pa has a voltage doubler. I think i can´t read the circuit diagram, hi.

I´ve done the tranfsormer test as described. After about 40 Minutes, the transformer is getting a bit warm, but not hot. I put my hand on the transformer and i think it is only a bit warmer than my hand.

I pulled out the rectifier and the filter capacitor board to measure and look at the capacitors. I measured every C out of the board with my C-meter and the caps seems fine.
I tried every diode - also fine. All the parts shows the same measured value(+/- 5 to 10 %) Also tested the resistors - ok.

Now I´m a bit in disorder. If it is not the transformer - and i think so now also - what could the thing be?

When I put the pa on and switch the meter switch on HV i can read only 1300 Volt. Few weeks ago i had 1900 and more volts on the meter. Is the fault on the meter board?

Hi

In the circuit diagramm you can see, that there is no voltage doubler in. I´ve checked the pa problem with ameritron by email. The result was also , the fransformer is the problem.

Was your HV reading a DC measurement? --No AC
Because I´ve measured direct the wires of the transformer.

Does your HV diode stack have an open diode? --No
I´ve checked every diode on the rectifier board.

Are all the capacitors good? --Yes
I´ve measured every cap on the board - ok.

Hi all,

I´ve got here an old AL80A from Ameritron. Since 1987 it works very fine here. But now i´ve only 1300Volt on the HV. Unsoldering all wires from the transformer for the measuring shows me the following:

HV (red-red) is 1335 Volt
FP-Voltage(yellow-yellow) is 10.5 Volt
Heating for tube (grenn-green-green)2.7V - 2.7V - 5.4Volt

Can anybody tell me the real measuring and the data of the transformer, so i can built a new one?

Does anybody know an adress in Germany/Europe where i can get a new one?

Ameritron told me, the transformer of the AL80B is the same, and a new one is abt. 125$. But the shippment is very large. Is this right?

Thank you for any answer.

73 es 55 de DH1OK

Olaf

Hi Steve!

First I´d like to say thanks to you for writing the code for the software. I use here a FT980 for a short time and now i`d like to CAT- him.

Have you tested your software already? What kind of Modem are you useing?

Please write back to DH1OK@darc.de.

73 es 55 de DH1OK