Reception Set (Canadian) VRL

 

 

Here's the receiver shown as it arrived. The missing knob was inside and the dial escutcheon is not original. Whether the home-made paper disk covers original markings remains to be seen but I can probably use my PC to print something better.

Below are two other examples of this receiver. You can see that there's going to be a lot of work needed to bring this receiver up to a respectable cosmetic state. Bolted onto the side of the upper case the last owner had added a 240-115 volt Radiospares autotransformer because the set was designed for North American mains.

The receiver is described in "Wireless for the Warrior Volume 3" which includes circuit diagrams and other information showing the receiver uses a staggering total of 19 valves, bearing in mind it's just a normal single convesion superhet (although it does have a 3-valve crystal-controlled calibrator). From information found on the Net it's likely that the receiver was designed to meet a particuarly stringent specification which is suggested by the number of RF, IF and AF stages of amplification. I understand it was paired up with a transmitter which failed to meet its specification, resulting in most of the receivers being used by themselves in the UK.

The receiver weighs in at 57 pounds whilst the power supply including the calibrator is a mere 31 pounds (plus the weight of that autotransformer). Ideally the two units should be fitted into a small rack for mechanical stability (as is shown in the example below left).

 

 

 

 Now some pictures of the interior of the main receiver, followed by pictures of the PSU box.

Below, a view looking down on the set with its cover removed followed by a view under the second lid. The loose knob needs securing to the phasing control.

You can just see a hole upper left under the magic eye where it appears a transformer has been removed and an alternative fitted below the chassis. This is a common fault because often a capacitor has been connected to the anode of an audio valve to reduce hiss and if it fails close to short circuit the transformer primary will fuse open.

 

 

Above... when I initially saw this picture, before I bought the receiver, I imagined it took plug-in coils or there was something really important that was missing, but after studying it I guessed those holes might have been for mounting valve holders to accommodate a set of spare valves.

A view of the underside followed by an enlargement of the writing.

 

 

 The receiver has clearly been worked on many many years ago by someone new to the hobby.

I'd need to look through post-war copies of radio magazines to figure out when these sets were sold in government surplus shops.

 

 

 

 

 

 

 

 

 

Below a view with the coil pack cover detached.

 

The receiver is vaguely similar in size and shape to the AR88 receiver except the power supply (with the calibrator and loudspeaker) are in a second case.

The open layout makes it very easy to work on the set. Nearly all the capacitors are of the metal-cased type and maybe more long-lasting than the common wax-covered ones which invariably tend to be leaky.

 

 

 

 Here are some circuit diagrams. First, that of the power supply with the crystal calibrator and loudspeaker (click to see full size)

 

 

 The receiver connects to its power supply via a cable harnessed from individual wires. The connections to these are shown above and are listed as follows:-

From left to right, 1 & 2 isolated heater wires, 3 chassis ground/HT negative, 4 preset HT feeding screen grids, 5 Stabilised 150 volts , 6 HT+, 7 Loudspeaker via speaker switch, 8 Speaker, 9 Second chassis connection for audio output transformer secondary, 10 Output from calibrator.

 

 Here's the schematic for the main receiver (click to see it full size)

 

 When I got this receiver it had been fitted with an auto-transformer to allow it to be used on UK mains but this had been (very inconveniently) screwed to the outside of the power supply case.

Below... I moved the VR150-30 stabilizer valve to a space adjacent to the loudspeaker giving me just enough space to mount the auto-transformer then did a little rewiring to return the connections to the relocated valve. As you can see bottom left I also fitted an IEC mains connector.
 

 

 Above is a block diagram of the receiver. Of note is the unusual high gain audio amplifier, a 6SF5; presumably the standard types such as the 6J5 wouldn't meet the stringent spec. Also of note is the use of a 6C8G in the calibrator. This valve was designed for use as a driver for a push-pull power amplifier and the best I can come up with is perhaps the two triodes were accurately matched and the designers chose this feature rather than using a common twin triode such as an 6SN7 for developing a "clean" multivibrator output?

I find it slightly surprising the designers used the Type 80 rectifier because this uses a UX base rather than the universal IO base used by the other valves. Maybe the manufacturers were using up an existing large stock of these?
 

 in progress

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