Wireless Set No. 19 MKIII. PSU arrangements?

[See_Mos]

Thanks for the VMARS link, I never knew there was so much information available for the WS19.

I sold my last one around twenty years ago, a complete Land Rover rack mount setup. I sold it back to the guy from Keighley that used to sell them at the radio rallies

[G4YVM David]

Grrr

Connected the 12v to test heaters...nice shower of sparks as I connected the ground the chassis, then nothing. No heaters that's for sure.

Oh well, the fun begin...

[Keith]

If you're putting 12V into the PSU (as opposed to the set itself), the dynamotor will take a hefty current to get moving. This might be too much for your 12V supply (unless you're using a car battery as I do!).

[G4YVM David]

I used a car battery into the set itself. I know from previous experience that my PSU is dragged down by the rotary inverter.

D

[llama]

There was a simple mod back in the '60s for converting the heater chain from 12 V to 6 V. From memory it was just to earth the hot end of the heater chain at the 807 and off you go. If this mod has been done it could cause the effects noted...
Graham

[G3VKM_Roger]

SWM November 1967, an article by F G Rayer on modding the WS 19. Downloadable on the American Radio History site:-

http://www.americanradiohistory.com/index.htm

73

Roger

[G4YVM David]

Thanks

D

[radiotechnician]

I do own a MKIII, with many accessories, including crystal calibrator, junction box with three snatch cords, variometer, etc.

Sadly the 120 VAC pack was retrofitted with a home built supply.

I do go back years with both the MK II and III sets.

My MK III is Russian/English, and has a Chinese decal as well.

As to the original AC power packs, they were almost totally useless because apart from the rectifier tubes, everything was enclosed in a large sealed metal case.

We tested hundreds of the MKIII AC packs and found very few good.


At one time the long 12 pin cords were in short supply, so I contracted to make them up, because the plugs were plentiful.

My reference folder for the MKIII was bought from the Military Museum and had all the schematics, and all the Canadian maintenance notes and revisions they had collected.

By a strange turn of events , I have a huge quantity of NOS E1148 and EF50 tubes, mostly from Australia on hand here.

My father worked for the telephone company during the war, and told of a group of engineers sent to England to gather manufacturing details for WS 19, which were to be manufactured in Canada. The ship on which theyreturning, was lost at sea because of enemy action. The plans then were flown over.

[Radio Wrangler]

There is a very high risk that any 19 set found today has been mucked about with. I'd check the machine through quite carefully against the manual before connecting to any power supply.

The 19 set PSU I stripped for bits in the sixties had a dual output dynamotor with three commutators. One for the 12v drive, one for 275v output and one for 500v.

DAvid

[Orakle42]

This is very interesting but surely the first question is do you wish to retain authenticity and use only a 12 volt power source with the original PSU or do you want to change to mains power only. Which ever option one chooses unless fitted in a vehicle a lot of the connections become redundant. This is why a lot of 19 sets have been "mucked about with". I altered my mkII example but retained a 12v power supply with a discrete option to use mains derived power rails., however, authenticity is lost because the original PSU is no longer required. The modification mentioned above about converting to 6v heaters is interesting, but think about the turn on surge!

Orakle42

[Keith]

One of the problems with using the dynamotor power supply is the amount of noise produced (of the audible variety, that is). In a WWII tank this was not a problem as it would have been hardly noticeable in a 130dB ambient. In a domestic environment, however, it is very tiring over a long period of use. I cheated slightly by interposing some pieces of hard foam between the dynamotor body and its clamp which helped a bit. If I was using it for extended listening I think I would knock up a mains PSU with the correct 12 point plug (socket?) that could be subsituted to give my ears a rest!

http://www.tibblestone.com/oldradios...radio/army.htm

[ex seismic]

That's where the Canadian supply wins, it can run on vibrator for receive and the dynamotor only kicks in on transmit. You have to remember to wait a second or so before talking to allow it to get up to speed. Mine runs off a mains 12v PSU with a 7Ah SLA to give enough oomph for the dynamotor to start.

Gordon

[G4YVM David]

A bit like the rotary relay on my T1154. Not so bad really, when you're sat between four Merlin engines...