BFO and WIRING

Below is the TenTec 460khz BFO, as supplied by Walters and Stanton for about £10, I suppose I could have made one, but to be honest I couldn't be bothered to scrabble around looking for the parts, getting lazy in my old age, it is a kit but easy to make up, although I had, or thought I had, trouble getting it going, as nothing seemed to be happening, until I realised the output is VERY low, not enough to operate my frequency counter, let alone using it by loosely coupling it to the antenna lead as in the docs!!! but by connecting it to the grid of the 2nd IF amplifier with about 10pf coupling cap it is VERY good, and transforms the old receiver, At this stage I simply couldn't resist trying it out on the air, all a bit temporary but I needed some encouragement to carry on, Two calls on the 7.03 mhz QRP channel and Dieter DN6WF came back, but very weak and I lost him in the QRM, after a couple more CQ's Hubert DF2MF came back and gave me a 559 he was 559 with me also both QRP as the old 18 set was pushing out about 1.2 watts, not bad for a first attempt, about 400 miles, my antenna is a 80/40 trapped dipole.

Next job after the excitement of the QSO's was to tidy up the wiring, the original power plug lead was in a bad way, the rubber insulated wires were just crumbling away, so I chopped them off and replaced them with some multi core wire and an octal plug that now plugs nicely into the new AC Power Supply as you can see below

Now you can see it is starting to look respectable with nice tidy wiring, there is still some temporary wiring around the old BFO coil but that will soon be redundant when the new BFO is fitted, I had to take the meter out again as the connections to the HT and LT are under it, I also had to change the metering resister as it was charred and open circuit.

I beginning to see the end of the first part of the project, if I can finalise the receiver tomorrow, the power lead needs rewiring and the BFO fitted, and of course the crystal socket for the transmitter, then I can think of putting it in it's case and having a play, I may leave the RF gain control as I was quite impressed with the old receiver with the QSO this morning...

Below is the Crystal Socket mod, they are simply two Wander chassis sockets spaced to fit a 10xj crystal, in fact they are these mini layer crystals soldered into 10xj cases but it preserves the vintage looks a bit, I have coloured the glaring white sockets with a bit of olive drab paint to make it look a bit "Army" and if you unplug the rock then the MO operates as normal.

And here below is the interconnection plug, which connects the receiver into the transmitter, this was missing so I have made one by drilling a disk of Acetal with the five pin layout slightly undersize and then inserting speaker pins with heat from my soldering iron, soldering on the wires and then using a piece of blue shrink wrap to make a nice tight electrical finish, it works well and will do until I can source the correct one.

And here below is the new BFO installed, mounted on the back of the tuning gang, it does look a bit incongruous a good demonstration of old and fairly new technology, and to be honest I feel a little guilty about using it but no more than using my Audio filter after the headphone jack, anyway there it is, at last it is time to put the whole thing together back in the box (usually fatal)

And now  for  Finalising the project

G3YUH