The set is in very good general
condition and from their appearance the valves are in new condition.
The top corner of the front panel is badly bent and the meter
glass is cracked but otherwise the set is in very good order.
The tuning controls were rather sticky and improved considerably
when I'd refitted them. I had to file off about a sixteenth of
an inch from the rear of the main tuning knob as this was rubbing
on the mechanism.
I temporarily removed the components in the area of the dent
and straightened the metal using a heavy bench vise as a press.
Before connecting the set with its ancillaries I tested the resistors
to ensure that these were within tolerance. In the event no resistors
needed to be changed. The decoupling capacitors are metal-cased
and none of the critical components showed any significant leakage.
The set was then connected to its various ancillary parts and
a quick test was made to ensure it was generally functional running
from a DC supply. To carry out further work I had to make a test
I identified the power input connections at the top connector
and fitted temporary cables for carrying 265-volts DC for the
main HT and 12-volts for the valve heaters.
A cable was clipped to the audio output connections at the lower
connector and this was connected to an audio amplifier and speaker.
The set received reasonably well on its two wavebands but performance
improved considerably when the IF strip and front-end tuning
The aerial tuning control was noted to be slightly out, as if
the inductance of both the tuning coils was a little high. As
the dial is set for optimum reception this is of little consequence.
I connected the set to an RF power meter and checked its performance.
The set employs a mixing arrangement so that there are several
frequencies present within the RF amplifier. It's important to
select the correct frequency when tuning up the set as it's possible
to tune to the (lower) image frequency produced at the output
of the mixer. I identified the correct signal and aligned the
set for best output on the 40m and 80m amateur bands.
To produce RF output one needs to connect an HT supply to the
RF amplifier. In the test rig I merely connected this to the
265volt receiver HT supply.
I noted an RF output of around 6-watts or so which will improve
when the full transmitter HT is supplied.
During testing I noted that in the CW setting the receiver produced
what sounded like a continuous side-tone that completely masked
the audio. This turned out to be audio feedback resulting from
insufficient loading at the audio output valve and is a known
design fault. I connected a damping resistor across the audio
output as recommended in the Army modification instructions and
this cleared up the problem.
The BFO is switched on in the CW setting and it may be varied
by the front panel control however, in this setting, the bandwidth
is significantly reduced for Morse code reception and this is
not optimum for receiving SSB. SSB can be resolved using the
net switch in the normal AM/RT setting but in this mode the BFO
is not adjustable.
The BFO wasn't apparently working when I first tested the set
and I discovered that the tuning slug in the coil was jammed.
This had resulted in loosening of the entire plastic former,
which was rotating inside the coil and not producing any change
to the frequency. I dismantled the BFO parts and removed the
coil. I was able to remove the tuning slug and after reducing
its size with emery paper it fitted and I was able to refit the
coil and reset the compound securing the plastic former in place.
I set the centre frequency of the BFO to correspond with the
IF. During testing I noticed hum on signals whenever the BFO
was switched on although this appeared to have been coming from
ripple on the HT supply I was using for testing and shouldn't
arise when the set is working with its correct ancillaries.
I noted that the meter reading for RF output was not registering
but from the circuit description I think this is because the
rectifier for the monitoring circuit is contained in an external
unit, which I didn't connect in the test rig.
MCW appears to work properly. Note that in CW and MCW the key
has to be removed for reception. I used a metal jack plug in
the test rig and found to my surprise that HT is carried on what
is normally the ground connection of the lead.
I found that there is what seems to be a regular AM net on 80m
and I listened to this for some time but didn't have a microphone
in the test rig so could not join in. The setting of the centre-tuning
knob should be adjusted for maximum RF output rather than best
Because the set employs very high gain in its front end you may
find it advantageous to make use of the RF gain control for best
signal to noise.