Contamination meter No 1 - UK Vintage Radio Repair and Restoration Discussion Forum

Paul-Harrison · 15th Nov 2023, 4:20 pm

Good afternoon
I have a number of contamination meter No. 1's some operational, what I cannot find is circuit / service information on the power supply units vibrator 666-110029 and mains 6665-110028 can anyone help? Regards Paul G8ADY

TonyDuell · 15th Nov 2023, 4:59 pm

I couldn't find anything official either, but I've attached the circuit diagrams that I traced out from my units.

Be warned that the mains supply is potentially lethal. One of the (easily touched) sockets on the top is directly connected to the red (live) wire of the mains cable!

Paul-Harrison · 15th Nov 2023, 5:45 pm

Hi Tony
many thanks, that must have taken a while! The mains unit is even simpler, a sealed main tx diode rectifier and cap, with fused op. As for keeping the fingers out of the way, don't worry, I started my working career in radio & tv some 60 years ago, when it was all like that! Regards Paul

TonyDuell · 16th Nov 2023, 10:58 am

You did notice that page 2 of the .pdf shows the mains unit I have. It's much the same as yours, a mains transformer, selenium stick rectifier and smoothing capacitor. But my fuse is on the mains side.

It didn't take me that long to draw the circuits out, I've done things a lot more complicated than that!

As for safety, I am used to dealing with mains on what I expect to be mains terminals. And with live chassis sets which are safely encased when in use. But I do not expect an exposed brass socket on the outside of a unit to be directly connected to mains live.

Paul-Harrison · 16th Nov 2023, 12:15 pm

Morning Tony, Sorry you are correct, I've only recently acquired the mains PSU, I've been looking for quite some time for one, only just investigating! I agree with about the live terminals at the base of the PSU as this can be removed from the main body by the operator still powered from the mains and NO warning signs!!

Uncle Bulgaria · 16th Nov 2023, 11:07 pm

TonyDuell's circuit diagrams were vital in repairing the one I got hold of (using Ukrainian Soviet capacitors to replace the leaky ones). I've attached some other technical details that you may find handy.

Paul-Harrison · 17th Nov 2023, 12:08 pm

Good morning, many thanks for your info, Tony's PSU circuits are a great help, its strange there appears to be no Info available for the two PSU units, Tony's comments about the dangers of the mains unit, the more I looked at it, more I thought what a dangerous bit of kit! I am considering putting an inline RCD on the input cable. I have two working meters, one with the Plessey connectors and one with the rubber connectors. I did the cap and diode changes some years back, I found a company in Canada "just radios.com" they do a wide range of HV caps and other bits. I have also re-built a duff CV2247 using the original rubber housing and packing in a Russian SB-180G tube, which works quite well, but I cannot seem to find them anymore.
Regards
Paul

Uncle Bulgaria · 17th Nov 2023, 12:35 pm

I've not seen a mains unit but they sound very dodgy! I guess the only use for it would be testing as field use would require the original batteries. The manual does show a stationary use case where personnel are being checked as they pass the detector, perhaps into a shelter.

I use mine with a vibrator supply on AA batteries, with a CV2247 from Langrex as the original was duff. I have one of the other type with the removable cap, which the manual says is for testing water for radioactivity, but that's defunct. GSTube has several Soviet geiger tubes including an SI-180G, but I'm not sure how advisable it is buying from Russia at the moment.

I think it's preferable to restrict serious use of such things to computer games like Fallout, whose retro-futuristic outlook I'm thoroughly enjoying!

m0cemdave · 17th Nov 2023, 6:08 pm

Interesting to see those old STC "Unistor" or "Q-type" rectifiers in the voltage multiplier stack. I have a box of assorted types lurking around here somewhere.

Paul-Harrison · 18th Nov 2023, 12:06 pm

Hi, many thanks for that information, I have been a mystified at what type of rectifier/diode type there are, I found some info which shows an advert from 1953 for the Unistor, and I believe it to be a Q3/3 because of the two orange bands, thanks Paul

m0cemdave · 18th Nov 2023, 9:06 pm

Yes, it looks like a Q3/3.

I'm not sure where I dowloaded this info from - possibly posted on here by somebody a year or two ago - but it may be of interest:

Paul-Harrison · 19th Nov 2023, 11:24 am

Many thanks for that, now it ties up with the No1 parts list info. This is hard to find data!

15th Nov 2023, 4:20 pm	#1
Paul-Harrison Triode Join Date: Jan 2011 Location: Bedford, Bedfordshire, UK. Posts: 12	Contamination meter No 1 Good afternoon I have a number of contamination meter No. 1's some operational, what I cannot find is circuit / service information on the power supply units vibrator 666-110029 and mains 6665-110028 can anyone help? Regards Paul G8ADY

15th Nov 2023, 5:45 pm	#3
Paul-Harrison Triode Join Date: Jan 2011 Location: Bedford, Bedfordshire, UK. Posts: 12	Re: Contamination meter No 1 Hi Tony many thanks, that must have taken a while! The mains unit is even simpler, a sealed main tx diode rectifier and cap, with fused op. As for keeping the fingers out of the way, don't worry, I started my working career in radio & tv some 60 years ago, when it was all like that! Regards Paul

16th Nov 2023, 10:58 am	#4
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,068	Re: Contamination meter No 1 You did notice that page 2 of the .pdf shows the mains unit I have. It's much the same as yours, a mains transformer, selenium stick rectifier and smoothing capacitor. But my fuse is on the mains side. It didn't take me that long to draw the circuits out, I've done things a lot more complicated than that! As for safety, I am used to dealing with mains on what I expect to be mains terminals. And with live chassis sets which are safely encased when in use. But I do not expect an exposed brass socket on the outside of a unit to be directly connected to mains live.

16th Nov 2023, 12:15 pm	#5
Paul-Harrison Triode Join Date: Jan 2011 Location: Bedford, Bedfordshire, UK. Posts: 12	Re: Contamination meter No 1 Morning Tony, Sorry you are correct, I've only recently acquired the mains PSU, I've been looking for quite some time for one, only just investigating! I agree with about the live terminals at the base of the PSU as this can be removed from the main body by the operator still powered from the mains and NO warning signs!!

17th Nov 2023, 12:08 pm	#7
Paul-Harrison Triode Join Date: Jan 2011 Location: Bedford, Bedfordshire, UK. Posts: 12	Re: Contamination meter No 1 Good morning, many thanks for your info, Tony's PSU circuits are a great help, its strange there appears to be no Info available for the two PSU units, Tony's comments about the dangers of the mains unit, the more I looked at it, more I thought what a dangerous bit of kit! I am considering putting an inline RCD on the input cable. I have two working meters, one with the Plessey connectors and one with the rubber connectors. I did the cap and diode changes some years back, I found a company in Canada "just radios.com" they do a wide range of HV caps and other bits. I have also re-built a duff CV2247 using the original rubber housing and packing in a Russian SB-180G tube, which works quite well, but I cannot seem to find them anymore. Regards Paul

17th Nov 2023, 12:35 pm	#8
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,215	Re: Contamination meter No 1 I've not seen a mains unit but they sound very dodgy! I guess the only use for it would be testing as field use would require the original batteries. The manual does show a stationary use case where personnel are being checked as they pass the detector, perhaps into a shelter. I use mine with a vibrator supply on AA batteries, with a CV2247 from Langrex as the original was duff. I have one of the other type with the removable cap, which the manual says is for testing water for radioactivity, but that's defunct. GSTube has several Soviet geiger tubes including an SI-180G, but I'm not sure how advisable it is buying from Russia at the moment. I think it's preferable to restrict serious use of such things to computer games like Fallout, whose retro-futuristic outlook I'm thoroughly enjoying!

17th Nov 2023, 6:08 pm	#9
m0cemdave Octode Join Date: Feb 2009 Location: Bletchley, Buckinghamshire, UK. Posts: 1,158	Re: Contamination meter No 1 Interesting to see those old STC "Unistor" or "Q-type" rectifiers in the voltage multiplier stack. I have a box of assorted types lurking around here somewhere.

18th Nov 2023, 12:06 pm	#10
Paul-Harrison Triode Join Date: Jan 2011 Location: Bedford, Bedfordshire, UK. Posts: 12	Re: Contamination meter No 1 Hi, many thanks for that information, I have been a mystified at what type of rectifier/diode type there are, I found some info which shows an advert from 1953 for the Unistor, and I believe it to be a Q3/3 because of the two orange bands, thanks Paul

18th Nov 2023, 9:06 pm	#11
m0cemdave Octode Join Date: Feb 2009 Location: Bletchley, Buckinghamshire, UK. Posts: 1,158	Re: Contamination meter No 1 Yes, it looks like a Q3/3. I'm not sure where I dowloaded this info from - possibly posted on here by somebody a year or two ago - but it may be of interest: Attached Thumbnails

19th Nov 2023, 11:24 am	#12
Paul-Harrison Triode Join Date: Jan 2011 Location: Bedford, Bedfordshire, UK. Posts: 12	Re: Contamination meter No 1 Many thanks for that, now it ties up with the No1 parts list info. This is hard to find data!