Trio jr500s comms receiver

[G8HQP Dave]

I was thinking of changing my HT rectifier from half-wave to full-wave, so I'm pleased to hear that others have done this. Were silicon diodes so expensive in those days? Did the bean counters get at the design when it went into production?

Another thing which caught my eye is the first audio amp triode - it seems to have a poor operating point (anode voltage too low), so it is in danger of taking grid current on peaks. This might explain the apparently low power output for an ECL82. Has anyone tried raising the triode cathode resistor a little?

[Alan Stepney]

As the new owner of the Trio JR500 that started this thread, I can see why Adi was less than impressed with it.
On first test, the sensitivity was far less than my CR100 (used for comparison as it was plugged in at the time).
Now, I know the latter were good receivers, but given the relative age...

A quick prod round with the AVO showed some unexpected voltages, and the cathode resistor of the 6BE6 was high. (It actually measured 3k.)
Replacing that and a couple of others and it all sounded much better.

Except on 80.
There, the sensitivity is minimal, in fact, a screwdriver on the grid of the RF amp produces far more signal.

I suspect that either someone has been twiddling cores & trimmers, or else there is a fault in the coilpack / switching.

Quite a nice receiver though.

[Station X]

As a contributor to the other thread on this radio I think this illustrates that it's all too easy to make invalid assumptions when giving advice remotely. I had assumed the receiver was working correctly when clearly it wasn't. Similarly in another case I assumed that the valves in a domestic set were in the correct sockets when they weren't.

I'm sure we'll all be interested to learn what you find wrong with the 80M band Alan.