Albrecht AE6490

[Jane]

The CB Albrecht AE6490 has a problem with transmitting. Front panel  shows that Albrecht transmits yet, no output power on antenna connector.So I would guess power amplifier could be faulty. What voltage should I measure on output antenna connector?

In the schematic, there are also few test points but not given a proper voltages.One is marked as TP1 Driver. I expect it should be an output voltage of a driver block. Is it an input voltage for amplifier block?
What voltage is normal for that driver output?
Thanks

[CJay]

Service manual is here:

http://www.cbradio.nl/abrecht/Service_Manual_Albrecht_AE6490_ENG.pdf

You won't be able to measure a DC voltage on the output, you need a dummy load, power meter or diode detector.

[Jane]

Thanks for the reply.
Unfortunately the schematic does not give test point voltage values.

>You won't be able to measure a DC voltage on the output
I know you are right but I do not understand the reason.
Is a modulation reason?

[CJay]

Thanks for the reply.
Unfortunately the schematic does not give test point voltage values.

>You won't be able to measure a DC voltage on the output
I know you are right but I do not understand the reason.
Is a modulation reason?

You don't need testpoint voltages, the collector of the final should be somewhere around 8V to 13V with no modulation but you will find it difficult to measure if there's RF present.

The reason you won't measure a DC voltage on the antenna socket because there should be no DC voltage on the antenna socket, there should only be RF which is high frequency AC, that's why you need the dummy load and a diode detector or RF power meter.

Does the front panel show power when you transmit?

[Jane]

Thank you for the reply.
>the collector of the final should be somewhere around 8V to 13V with no modulation but you will find it difficult to measure if >there's RF present.
How to check that the final transistor( collector) is working properly and a problem is behind it?Or how to check that there is RF present or not ?With a scope?

Yes, the front panel shows power when I transmit.
Do you have any idea how to continue with a repair?
Thanks.

[CJay]

What test gear do you have?

[Jane]

I have a power meter, dummy load, scope 200Mhz, digital multimeter