Wireless Set No. 52 Canadian - Project

[David Dunlop]

I have been running the Remote Receiver each evening for a week now, between 30 minutes and an hour each time.

The valve readings from the meter have stayed very close to those initially recorded when I first fired the receiver up. The background noise seems to have dropped off a bit on the loudspeaker when listening to the WWV Time Signal and this is still all with the RF Gain at 'maximum' and the AF Gain at very close to maximum. The crystal calibrator pips are still somewhat buried in the background noise.

I decided to add another test to the mix on the weekend by checking out my Receivers, Headgear, MC, Mk.1 in both PHONES sockets. I figured this would tell me what both sockets were up to, that the Receivers Headgear worked and that the toggle switch between the loudspeaker and the headgear also functioned properly. Pleased to report all items responded correctly, but one point did surface I am curious about.

This is the first ever wartime wireless set I have ever worked on/listened to that is equipped with an installed loudspeaker. What I noticed straight away was the level of background noise seemed much greater via the loudspeaker circuit than the headgear circuit. I had to back off the RF Gain nearly 1/4 from full maximum and the AF Gain by about 20 % from where these two controls were set for the loudspeaker, when I was listening to the set via the headgear. I also noticed that through the headgear, the crystal calibrator signal was very clear at all three positions compared to when listening with the loudspeaker. The speaker is identified as:

LOUDSPEAKERS, 3-in, PM, 3.5 Ohms

Now it is still quite possible that some of the valves are not fully up to standard and this may be influencing the level of background noise I am experiencing, but can anyone advise if, in general, it would be expected for a wartime era loudspeaker in a wireless set to have a noisier output than a set of headgear?

David

[David Dunlop]

At this point, some of you might be interested in what the 52-Set Remote Receiver setup looks like powered up, so here are a couple of photographs of the receiver warming up on it's own, and with the Crystal Calibrator also warming up.

Nice to see the red indicator lamps finally glowing. I cannot help wonder when that last happened.


David

[Bruce MacMillan]

A sight to see emitting only photons and not smoke.

Nice set, winter is coming, maybe a qso across the pond.

[David Dunlop]

Yes, Bruce, I am quite pleased at how things have been progressing and I do hope the ethers tidy up over the Winter season enough to improve the listening experience.

I have been able to confirm that the R58A resistor in my Remote Receiver has packed it in. It is a pair of 1.2M Ohm resistors actually. The Master Parts List provides two options of a single 600K Ohm or the aforementioned pair, but of the three receivers I have for inspection, all are equipped with the paired arrangement. I wonder if the single resistor configuration was very early production, or very late?

In any event, both of this particular pair are fully open and toast. I have tracked down a supply of carbon composite resistors that match the factory originals and once on hand will swap the offending pair out. Took a while to track down the location of the R58A on the chassis but did finally find them, with the help of a nice bright LED torch, sitting on the long terminal board on the underside of the chassis. See the attached photograph. They are the pair immediately right of the empty pair of terminals on the right half of the board.

I think I may take some time to ID all the other components on this board for future reference. Particularly the resistors. In poor lighting, the background colour and the aging of colours can make it a bit of a challenge to spot the typical resistor colour codes easily.

David

[Chris Suslowicz]

Originally Posted by David Dunlop

Yes, Bruce, I am quite pleased at how things have been progressing and I do hope the ethers tidy up over the Winter season enough to improve the listening experience.

I have been able to confirm that the R58A resistor in my Remote Receiver has packed it in. It is a pair of 1.2M Ohm resistors actually. The Master Parts List provides two options of a single 600K Ohm or the aforementioned pair, but of the three receivers I have for inspection, all are equipped with the paired arrangement. I wonder if the single resistor configuration was very early production, or very late?

600k is not one of the 'preferred values' in general use, so while it might have been the designer choice in practice it would have been a pair of 1.2M resistors (which are in the E12 preferred value range). The closest single E12 value otherwise is either 560k or 680k (all values +/- 10%. A pair of E12 resistors meant one less specialised stores item (that may just have been used in that receiver) that needed to be carried by workshops.

Chris.

[David Dunlop]

That would explain it, Chris. Thanks.

I did actually find one supplier in the States with NOS 600K Ohm carbon composite resistors correctly rated for this receiver, but passed on them because they seemed an odd/rare value and I wanted to maintain the original configuration of the Remote Receiver. Interestingly, this same supplier also has a stock of NOS in the box Delco Dynamotors for the 19-Set. Amazing what turns up when you don’t need it.

David

[Bruce MacMillan]

Actually 600k was a standard value of resistance. The E series of resistance is the EIA values that weren't adopted until 1952. Prior to that resistors had values like 400k, 500k, 600k,etc. Have a look at an early Allied or other distributor catalogue. Same applied to early capacitors. Old values of 0.02 & 0.05 became 0.022 & 0.047, etc.