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allgemeine Kategorie => mcHF Projekt Deutsch / English (here you can discuss everything related to mcHF) => Message started by: WD8BXS on 18. July 2019, 10:36:23

Title: Lost IQ adjustment
Post by: WD8BXS on 18. July 2019, 10:36:23

I have a version 6 radio in for repair that has lost its IQ adjustment.

I see some sporadic signals, and the IQ adjustments have no effect.

Any ideas??

de WD8BXS, Chuck

Title: Re:Lost IQ adjustment
Post by: DF8OE on 18. July 2019, 10:41:33

Hi Chuck,

I am guessing you are talking about RX...

It looks not like a software error but a hardware error. But you have to do more investigations. Take a signal generator and report what happens...

I am nearly sure one path (I or Q) is out of order ::)

vy 73
Andres

Title: Re:Lost IQ adjustment
Post by: WD8BXS on 18. July 2019, 14:44:26

Sorry, no, this is on transmit

Chuck

Title: Re:Lost IQ adjustment
Post by: DF8OE on 18. July 2019, 15:01:40

What do you mean with "sporadic signals"? Do you see a signal but not constantly? What ybout the frequency - are there two peaks transmitting? Or is the frequency hopping, too? Or is the output power hopping?

vy 73
Andreas

Title: Re:Lost IQ adjustment
Post by: WD8BXS on 18. July 2019, 15:24:09

Here are pics of the receiver.

Transmit power on MCHF is .5 watts
40 meters, 20 meters, 80 meters

Title: Re:Lost IQ adjustment
Post by: WD8BXS on 18. July 2019, 15:24:39

Title: Re:Lost IQ adjustment
Post by: WD8BXS on 18. July 2019, 15:25:00

Title: Re:Lost IQ adjustment
Post by: DF8OE on 18. July 2019, 15:44:24

Trace af from pin2 and 3 of boards connector via opamp to the four inputs of the mixer.
Look if 90° lo signal is present at the mixer.
Look if all three connections from mixer output transformer are good.

vy 73
Andreas

Title: Re:Lost IQ adjustment
Post by: WD8BXS on 18. July 2019, 16:33:22

OK, will test that circuit later.
Thanks
Chuck