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Old 18th Nov 2018, 10:27 pm   #1
3pinplug
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Default Any Marconi TF995 A RF Signal Generator Owners Help?

Hi
Just got a TF995A/3/S which has a circular 3pin socket on the front of the unit left-hand side, assuming this is the mains input. Initial googling suggests this lead is not available anymore, so has anyone else had this problem and modded their unit to remove the need for this type of powerplug?
If you have any chance of some pics so i can see if this thing works?
Thanks
Mark
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Old 18th Nov 2018, 11:16 pm   #2
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Hello Mark

I used to have a TF995A, but can't remember the power input arrangement.

I wonder if the attached picture is the same type as on your unit? If so, its a Bulgin standard 5A type, as was fitted on lots of equipment during the 50s & 60s.

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Old 18th Nov 2018, 11:23 pm   #3
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Does it have a threaded alloy outer shell- if so, it's likely to be a Plessey Mk4 type. It was widely fitted on mains-supplied kit used by the military (like older Marconi signal generators). It falls short of modern safety expectations on several counts- I don't like them one little bit!- but they are available from a few sources for those who like to keep kit original.
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Old 19th Nov 2018, 6:54 am   #4
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Thanks both for the replies. I will take a picture this evening when I get in from work and post it here. It does sound like the Plessey item, but I will post a pic to confirm.

Thanks, Mark.
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Old 19th Nov 2018, 10:22 am   #5
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Like this?

https://www.radiomuseum.org/r/marcon..._tf995a3s.html
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Old 19th Nov 2018, 11:24 am   #6
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Yes thats the one the round connector is shown bottom left.
Regards
Mark
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Old 19th Nov 2018, 12:47 pm   #7
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

With the metal, coarse-threaded ring around the connection s?

That looks like a Plessey Mark IV connector.

David
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Old 19th Nov 2018, 1:28 pm   #8
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

It does look like a Plessey connector also used on other Marconi equipment.

John
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Old 19th Nov 2018, 9:34 pm   #9
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Hi all
This is the connector, heres a pic! It seems to have some plastic inside meaning it needs a particularity shaped plug, is it definitely the MkIV
Thanks all
Mark
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Old 19th Nov 2018, 10:47 pm   #10
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

I have some of these connectors in stock
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Old 23rd Nov 2018, 11:29 am   #11
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Is it possible in theory to convert the Plessey connector to say a three pin kettle plug style, if they are hard to get may be a better solution. Anyone else done this sort of mod?
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Old 23rd Nov 2018, 7:00 pm   #12
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Sorry, been away with work.

As I have said, I have some of these, admittedly not attached to a mains lead, but if you are ok with sorting that I can help you - PM me your address, and I will get one to you.

Sean
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Old 23rd Nov 2018, 8:18 pm   #13
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Quote:
Originally Posted by Dodgeb200q View Post
Is it possible in theory to convert the Plessey connector to say a three pin kettle plug style, if they are hard to get may be a better solution. Anyone else done this sort of mod?
Perfectly possible in theory- but as it's a prominent front panel connector, some may feel that it detracts from i's originality. It's one of those things that can get a bit contentious in the vintage world- I don't like to carve things up, but I do make an exception where primary-side safety is concerned. There are quite a few things here that have been converted to IEC C14 panel plug inlet- it's a bit big and clunky for most forum-type needs but it's about as widely and currently safe and approved as this type of thing gets. Later Marconi kit, like the TF2002AS here, was made of a notably soft aluminium alloy that is very quick and easy to make bigger holes in- had the mains panel been more accessible, I reckon I could used my teeth rather than a file when replacing the horrid fragile little round Bulgin bakelite connector with an IEC C14!- but the old sturdy steel stuff would be harder graft
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Old 23rd Nov 2018, 9:04 pm   #14
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Hi turretslug
Thanks for sharing your experience, interesting about the thickness of the front i hadnt considered that, luckily though just been offered one of the proper connectors so hopefully can fire this thing up at last, thanks sgain and thats one set of teeth you have there!
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Old 1st Dec 2018, 7:34 am   #15
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Is it possible to re orientate the black keyway on a plessey mk4 mains connector or the chassis socket to make them the same alignment if they are a bit out?
If so any ideas how you do it?
Thanks
Mark
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Old 1st Dec 2018, 9:00 am   #16
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

The lead-in nut on the rear and the slotted/castellated nut behind the knurled collar on the rear needs to come off, there was a special tool kit with spanners issued for this. In fact, I think I recall someone posting some photos of one here a few years ago. Then you assemble it, realise you've still not got the orientation right, take it apart and do it all over again.

Andrew
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Old 1st Dec 2018, 10:21 am   #17
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Copy photo of Plessey tools attached.
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Old 1st Dec 2018, 10:46 am   #18
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Its very nice if you have the special tool kit for working on these connectors. But it is not essential (just as well because they rarely come up for sale!). For years I reoriented and repaired these connectors with just a pair of pointed nose pliers, a straight blade screwdriver, a small hammer and a vice.

You can hold the connector in a vice - soft jaws are obviously a big help here to avoid distorting the light ali shell. Then you can loosen the back circular ring nut with a screwdriver in one slot and some light taps on the hammer just to get the thing started. Then the pliers can be used with one "nose" in each slot and just slowly rotate the thing undone. Similarly with the inner locking ring. Its fiddly - but doable.

Richard
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Old 1st Dec 2018, 10:53 am   #19
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

Brilliant! Thankyou very much i will have a go and report back
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Old 1st Dec 2018, 12:08 pm   #20
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Default Re: Any Marconi TF995 A RF Signal Generator Owners Help?

I agree, the special tools are not essential. Pointed nose bent jaw or circlip pliers are the most useful.

John
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