The Panda Cub transmitter survived a 900Km trip in the boot of the car. Despite the rough handling and a bit of accumulated rust, it fired up just fine.
I used a 240V 50W lightbulb as a dummy load, (it has a cold resistance of 70 ohms, no idea what it goes to when hot), and it certainly puts out a little power.
There's not a lot of information available on the internet about the Panda Cub. There are a few mentions and mostly information about the larger sibling by the English Panda Radio corporation.
A circuit in my bad handwriting is available in the scans of the old Contronics humour magazine here, and here.
It's a very simple design with a single 807 in the final. If anyone could point me to a user manual I would be most grateful.
Over the years the built in modulation circuitry has been decommissioned and the unit must be modulated by plugging in a 30W audio amplifier drive through a socket in the back.
Also, the frequency multiplier that made this a multi-band transmitter isn't there anymore so this is now a 160m AM transmitter which is fine by me.
Dallas tells me that the metal covered 6AG7 valve has an "N" on it because it belongs to Nigel - let me know if you need it.
I'm modulating it with a 100W RMS amplifier (way more than enough) and it's looking good:
The trapizoid (audio on the X axis, RF on the Y axis) shows a phase problem, not sure how serious that is.
Would you believe I purchased this in the 80s for $10 at an auction. I count myself very lucky.
The next challenge is an antenna for 160m...
I've hammered an earth stake into the ground at the base of the neighbour's gum tree and run up an inverted L with a 10m vertical and 12m horizontal part.
A test transmission over the weekend sounds terrific on a transistor radio while I walk around the block but I don't think I'm getting out much more than that - no one responded to my calls during the Sunday morning VK2WI 160m callback.
No doubt more inductance is needed to make this work a bit better.