----- Original Message -----
Sent: Wednesday, September 22, 2004 1:10
PM
Subject: LF: Re: PORTADYNE
You should be able to make out the circuit just
by looking at the underside of chassis.
I thought all G3's could draw the circuit
of a simple 4 valve TRF rx from memory and first principles having built
several as teenagers ?
You are correct I could rebuild it from memory
without any cct info but I want to put it back to the original
cct.
My first RX built was a 3 valve TRF around 1952
and it worked first time !!!!!!!
War surplus radios then appeared and I modified
just about all that were available at the time!!! both RX and TX
I have met some G3's that could not solder two
wires together, nor have a QSO using CW. Where do you fit in
?
My first rigs were built using a soldering iron
heated on a primus stove, out in the wild open spaces in TYRONE.
One of the v. condensers is almost
certainly the "reaction" control. [positive feedback in
modern terms ] although the same result could be obtained by the variometer
you describe.
Not a reaction control. Both variable condensers
are connected to the main tuning dial.
Start with loudspeaker leads (high impedance in
series with the anode of output stage) one will got to output valve anode. the
grid of that will take you (via condenser) to anode of audio stage and the
grid of audio stage to the detector valve.
Bryan G3GVB
----- Original Message -----
Sent: Tuesday, September 21, 2004 4:48
PM
Subject: LF: PORTADYNE
Hi All.
Thanks to the response about the Portadyne
radio. Here are the answers to the questions asked.
Tech details:
4 valves
Battery leads consist of 2 leads poss
LT, 2 more for HT and a couple of others poss bias. The set is so old
that the leads have virtually disentegrated along with the internal wiring
on the chassis.
2 independent tuning condensers, each with
own knob each side of cylinderal dial on top middle of RX facia,
to left is on/off
switch and to the right is what looks like a small variometer that would
appear to interact with the loop antenna winding.
(looks like a lollipop) The dial has lost its
markings so cannot identify any anything, would not be freq or wavelength
because its so narrow. Possibly just graduations.
There is a very crude loudspeaker to the front
of cabinet and on the outside there is a screw adjustment about the centre
of the speaker for some sort of sensitivity adjustment I suppose.
The cabinet is wooden 15 inches high and 14
inches wide. The front appearance is fretted and flaired. The controls are
under a lift up pannel on top of the cabinet.
There are no coils except what appears to be a
choke type inductor and the frame aerial winding around the inside of the
cabinet.
This would be a TRF type radio with a RF stage,
top of the range in its time !!!!
I expect is must be one of the first valve type
radios and some of you old timers will know its exact age and maybe have a
cct for it.
Thanks for the 11 replies showing a lot of
interest, it probably covers MF and LF, the tuning is odd ball with both
condensers moving the dial independently.
The valve bases seem small compared to the UX5
and UX7 type but similar pin displacement.
There could be a pint or a wee whiskey for
the first one to come up with a cct diagram
The cabinet is in good condx but the chassis is
corroded but not too bad, the wiring has just about gone.
More info welcome.
de Mal/G3KEV
