Wireless of the Week - week 52

[Jon Skagfeld]

Wow!

Who would have thought that "old" radios/comms equipment of a certain era could take a year to demonstrate/display/explain?

Good job Bruce. Many thanks.

Looking forward to the index so I can file it away in my favourites for future reference.

[benamucke]

Shucks was waiting for a write up and pictures for the R107 Reception set. Never the less You did a wonderful job.
Ben in Toronto

[David Dunlop]

Jason.

Two or three years ago, somebody in either the UK, or Western Europe, was making excellent reproductions of the No. 23 Carrier. They might even have been mentioned somewhere here on the forums.

David

[benamucke]

Originally Posted by Jon Skagfeld

Wow!

Who would have thought that "old" radios/comms equipment of a certain era could take a year to demonstrate/display/explain?

Good job Bruce. Many thanks.

Looking forward to the index so I can file it away in my favourites for future reference.

Sorry no measurement but have two picturesBase No 3 (1).jpg

Base No 3 (2).jpg

[cletrac (RIP)]

Well, Bruce's weekly threads made for a year of interesting reading. Thanks so much!

[Bruce MacMillan]

I add my thanks to Bruce for this series. Many of these sets have passed through my hands over the years and it was great to see them again.

It's a wonderful collection you have, Bruce. Your postings show that not everything is about rusty old trucks.

[wendel daniel]

hello
Thanks for this presentation. A wonderful set.
You have just an incredible collection,
thanks for all
daniel from france

[wendel daniel]

hello
I find this set today.
Could someone tel me the voltage and amp i must have for work with this set ?
Thanks for all
daniel from France

[Chris Suslowicz]

Originally Posted by wendel daniel

hello
I find this set today.
Could someone tel me the voltage and amp i must have for work with this set ?
Thanks for all
daniel from France

Hi Daniel,

The set will operate from either 12 or 24 volts. You need to slide the power unit out of its case and check the position of the switch on the top deck.

If set for 12 volts you can run the set on vibrator (if the vibrator is OK) for receive, and the dynamotor will start on transmit.

If set for 24 volts it will only work on the 'Dyn' position (the vibrator is 12V only).

Before trying it out you need to test (and probably re-form or replace) various capacitors in both set and supply unit to prevent permanent (and expensive) damage.

First, check the fuses fitted to the supply unit. The output (HT1 and HT2) should be 250mA and higher rated fuses must not be fitted they are to protect the dynamotor against short circuits that could destroy the output windings. (The vibrator fuse is 10 amps and is there to protect the vibrator transformer from a 'stuck' vibrator.)

You need to check the following capacitors before applying power:

Power unit.

C32A the large electrolytic on the top deck - this can explode if faulty due to internal pressure build-up.

C105A/B the dual electrolytic next to the vibrator socket.

Set.

C16A - the cathode decoupling capacitor on the 6B8G (V3A). If this has failed (low resistance) there will be no grid bias on the audio output stage, the 6B8G will be turned on very hard indeed, and the audio output transformer (T2A) primary winding will fail. This is a very expensive item to replace.

All the 0.1uF capacitors need checking, but are unlikely to cause damage if power is applied briefly to the set.

Input current: The specification is 7.1 Amps on receive (all on) 10.7 Amps on 'A' set transmit. I assume that's for 12V input and that 24 volt operation will be about half that.

You will have great difficulty running it from a 12V power unit because the dynamotor acts as a short-circuit on start-up and will cause overload trips to operate. It should run on a 24 volt 15 amp supply (mine does). A solution to the start-up current is to connect a 12-volt lead-acid battery in parallel with the AC supply unit output (connect battery to set, then switch on your bench supply before connecting it to the battery in case it does not like voltage on the output terminals when it's switched off), then switch on the WS19 supply unit and check the LT voltage on the set meter. (Check the polarity is correct and that it reads around 12 volts and does not go backwards!)

(If the dynamotor runs slowly and draws about 20 amps with no load on it, it's faulty (short-circuit armature) and you need to get another dynamotor.)

Hope this is some help,

Chris.
(I wrote a long article for the WS19 (UK) group on the Canadian Supply Unit No.2, should I dig it out and re-post it here?)