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Old 27th Dec 2016, 11:13 pm   #1
Oliver35
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Default Radar model 202- not quite as it should be?

Hello, I hope all have had a good festive season. I received the above Radar CRT tester/rejuvenator as a christmas pressie this year, which I'm delighted about. It's missing the test lead and adaptor, but I've got some multicore cable and a nice bulgin Octal plug, so I'll make one up when I get a moment. However, I opened it up today to replace the iffy rubber flex, and it seems a wicked hand has been at work, as all is not as it should be. There's a large RS 100uf cap hanging off the back of the meter, held in place by a length of string, a broken pot, a neon bolted to the front panel but not connected to anything, and another neon soldered across the internal octal socket that looks like it's had a rough life. Looking at photos online, I have a suspicion that it's meant to be inside the plug along withe the two resistors. Equally helpfully, the LT thermal cutout has been soldered together, so I've got some tidying up to do.
Can anyone here point me in the direction of a schematic, and ideally a manual for this instrument? I did a quick forum search and didn't find anything, this may be attributable to my own inefficiency.
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Old 27th Dec 2016, 11:53 pm   #2
MotorBikeLes
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Default Re: Radar model 202- not quite as it should be?

Can we have a photo of the front of the unit please?
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Old 28th Dec 2016, 10:46 am   #3
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Default Re: Radar model 202- not quite as it should be?

Better than having nothing but hopefully someone may have a copy.

http://www.instruction-manuals.co.uk...n/radar202.htm

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Old 28th Dec 2016, 9:47 pm   #4
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Default Re: Radar model 202- not quite as it should be?

Yes, photo of the front of the unit no problem. I'm not sure how much the 202 changed over the years, this is the first tester I've owned. Being naturally suspicious of any modifications that involve string (at least for any purpose other than looming) I want to put it back to standard, which is why I photographed the areas of meddlement first, but it would be interesting to speculate as to what the original owner was trying to achieve by deviating from the original circuit..
Andrew, thanks for the link- I may follow that path, as it's the correct manual. Somehow postal orders seem terribly archaic, although I suppose it wasn't that long ago they were the mail-order currency of choice..
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Old 28th Dec 2016, 11:23 pm   #5
MotorBikeLes
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Default Re: Radar model 202- not quite as it should be?

There were a couple of neons in the earlier pics if I recall. Is there a sngle valve in there as well? I may have a circuit.
I had one of these almost 40 years ago, long since dismantled when I met better (possibly) testers, but some of its internals live today in my own design of test / rejuvenate instrument, including the meter.
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Old 28th Dec 2016, 11:55 pm   #6
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Default Re: Radar model 202- not quite as it should be?

There is an example on Radiomuseum and that also seems to have the resistors in the valve base.

http://www.radiomuseum.org/r/wavefor...vator_202.html

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Old 29th Dec 2016, 12:16 am   #7
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Default Re: Radar model 202- not quite as it should be?

Despite the link, instruction-manuals.co.uk no longer operates, so beware.

In 1961 these were being sold off cheap £17.17/6 by Harverson Surplus.
Mine came with a lead to suit different crt bases.
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Old 29th Dec 2016, 6:49 pm   #8
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Default Re: Radar model 202- not quite as it should be?

Les- no, no valves in the unit, just those neons, and only one of those is connected to anything. Looking at the internal photos on the Radiomuseum site, (thanks Mike, it's about the only thing that comes up with a Google search, which surprises me) it looks as though the unit should only contain one neon, and that should be inside the valve base with the two resistors, although to which pins, I'm not sure. The rather stressed neon in mine is soldered to a couple of tags under the socket, but given the quality of the tinkering I wouldn't care to rely on their being the right tags.

Quote:
Originally Posted by Restoration73 View Post
Despite the link, instruction-manuals.co.uk no longer operates.
Thanks for that, I would blithely have sent a cheque off to what appears to be a functioning enterprise. You'd think they'd take the site down, or at least put a note to that effect somewhere. So, back to square one- does anyone have the manual/ schematic?
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Old 30th Dec 2016, 12:00 am   #9
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Default Re: Radar model 202- not quite as it should be?

Somewhere I have a tester circuit containing a thyratron, but in view of your answer, sorry I don't.
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Old 30th Dec 2016, 12:27 am   #10
Oliver35
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Default Re: Radar model 202- not quite as it should be?

No worries Les, thanks in any case.
I have had a few minutes to have a closer poke around inside this afternoon. I've fitted a new rubber mains flex and had plenty of opportunities to curse the general construction. I stripped out the bodged-in electrolytic, and paid rather closer heed to it than I had on first inspection. It's actually a 100uF + 100uF combined can, and whoever it was that waded into this thing failed to connect the common neg of the can to anything, so in fact it wasn't doing anything anyway. Rather makes you wonder what their TV repair skills were like. I've also returned the neon (or rather the second, redundant but much healthier one) to the valve base, using a combination of where the previous owner tacked his in (dodgy), where it appears to be on the Radiomuseum photos, and where solder traces indicate a missing component (more promising). I think I've got it right, although I'd like to have an authority to check against before turning it on a valuable CRT. I also need to turn my cupboards out to see if I have a replacement for the 15 ohm wire wound pot that's broken. It seems a very low value, but taking a reading across what's left of it seems to confirm the value..

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Old 30th Dec 2016, 1:15 pm   #11
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Default Re: Radar model 202- not quite as it should be?

Plenty of 5 to 25ohn WW pots to be had if you strip an early Dual Standard CTVs convergence board.
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Old 30th Dec 2016, 2:27 pm   #12
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Default Re: Radar model 202- not quite as it should be?

If you need any further pictures of an unmolested set i am happy to email to you.
Connection from the CRT tester to the adaptor box is via an International Octal socket, and the connections are thus:

Pin 1 = Heater
Pin 2 = Heater
Pin 3 = n/c
Pin 4 = Cathode + A2 - this is on pentode tubes with the B12A base, connection is also made to pin 6 (marked i.c. in some books)
Pin 5 = Grid
Pin 6 = A3 - on the Radar this is a flying lead designed to connect to the final anode of the tube, and is a special 3-in-1 connector.
Pin 7 = A1
Pin 8 = n/c
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Old 30th Dec 2016, 5:18 pm   #13
Oliver35
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Default Re: Radar model 202- not quite as it should be?

Stephen, that's enormously helpful, thankyou very much. I've dug out today a Bulgin Octal plug to make the lead up, I just need to find/fabricate a box for the other end. I had found the pin connection details on the archived 'other' forum- which, from the identical wording, I assume you posted yourself!
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Old 30th Dec 2016, 6:54 pm   #14
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Default Re: Radar model 202- not quite as it should be?

Perhaps connecting the 100/100 cap one lead to each cap positive and nothing to common neg would have the effect of making up 2 caps in series back to back, so making a non polarised 50 Mfd cap,

could this have been the intention ?

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Old 30th Dec 2016, 7:39 pm   #15
Oliver35
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Default Re: Radar model 202- not quite as it should be?

I suppose it would, although it seems an odd way of going about it. If you've got one floating about, I suppose. Still not sure of its purpose though, it's not replacing anything else as far as I can tell. There's also a mystery pair of banana sockets on the front panel that don't seem to be standard. Ought to investigate those, too.
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Old 30th Dec 2016, 7:54 pm   #16
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Default Re: Radar model 202- not quite as it should be?

Comparing yours to mine seems to suggest the capacitor in yours has been added to boost the "clear short" ability or because the double can capacitor was no good. (it was knackered in mine on both sections)

the neon has been added to the outside of the octal plug in instead of inside so to speak. No ideas on the neon near the meter, is it connected ?
Those banana sockets may just have been added to provide easier selection of modern sized plugs ?
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Old 31st Dec 2016, 2:01 pm   #17
Oliver35
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Default Re: Radar model 202- not quite as it should be?

I initially assumed that the alien capacitor was to replace one half of the electrolytic, but it didn't go directly across it, nor had the old cap been disconnected. It may well have been an attempt to give an extra wallop to the clear short function, but I've removed it now. The neon near the meter wasn't connected to anything, so I've assumed it was just there as a 'spare'- I've installed it inside the plug and removed the blackened one.
As for the banana plugs, I'll have to trace them back- there's no continuity between them and the ohms/volt sockets, so it's currently anyone's guess..
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Old 31st Dec 2016, 2:05 pm   #18
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Default Re: Radar model 202- not quite as it should be?

I have found this rejuvenator to be magic for bringing back the mazda triode tubes when others have failed.
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Old 10th Jan 2017, 10:49 pm   #19
Oliver35
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Default Re: Radar model 202- not quite as it should be?

Thanks for all the help on this thread, it's been extremely useful. I've finally found a sufficient quantity of my tools, bits and pieces after the frantic Christmas tidy-up to crack on, and have now fitted a new rubber flex, and put the innards of the Radar back to the way Waveforms intended them to be- or so I hope. I should double-check the dual cap, but there are no unhappy noises when it's powered up. I've also, after many burnt fingers and choice words (I hate those Bulgin octal plugs- they look the business, but I find them very fiddly to solder up) made up a test lead and adaptor for it, so once I can get up in the loft and retrieve a tube, I can go a-testing. Although at the moment only on tubes with Octal or B12A bases, as that's all I have.
I've also found, in my collection of odds and ends, a long co-axial plug for the 25kv socket, such as was on the HV probe these originally came with. I'm assuming these were resistive probes, such as those for AVOs*, etc? No great shakes, as I have an EHT meter, just interested.

*Which reminds me, I should get on and fix the AVO 40 I was given for Christmas last year..
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