Hi guys,
I've just had the chance to have a closer look at my QDX, mainly to see why, to me, it's only outputting half power.
I've changed all the BS170s, and IC5 and the issue still remains. I've checked solder joints on T1 and L14, plus all the others. They seem to be okay.
So what I've got is this:
Supply voltage: 11.49V
Using a DVM connected to a QRP-Labs Dummy Load:
On TX (40m) 23.84V,?(30m) 24.25V,?(20m) 24.86V,?(80m) 24.75V
Average being 24.725V. Using the usual (X*X)/400 gives 1.528W.
If the 24.725 is doubled it gives 49.45V. The formula above then giving 6.11W. So to me the issue is this half voltage to what it should be. A reply to my original post indicated that IC5 is probably toast on one side of the BS170 drives, so I've just changed that along with all the BS170s, however the issue still remains.
Voltages on IC5, p8/11 and p3/6 during RX are 0V. On TX they are 2V6 so that seems to indicate IC5 is okay.
I'm now at a loss as to what's causing the problem. I've managed to procure another QDX from the new batch so I can later use that as a reference to compare with, well assuming that unit doesn't have issues once I've built it ha ha.
Has anyone got any ideas on what to check next?
73 de Robbie M1ROK
