Marconi TF 2700 Universal Bridge

[Andrewausfa]

I bought this bridge the other week as I seem to have run out of radios to fix as well as room to store them. I thought repairing a few bits of test equipment wouldn't go amiss in the interim (i.e until BVWS Harpenden).

This one looked as if it been stored in less than ideal conditions being filthy both inside and out. It looks as if it has had a rather rough life with the case being a bit battered and nice dent in the front trim surround. Parts-wise it was missing the battery connector and the 2BA screws which secure a panel on the rear. Despite my misgivings that this bridge may have been chucked in the loft because it was broken, a quick fudge with some flying leads and a PP9 proved that there was hope. The set was taken apart and very carefully cleaned inside, the case was chucked in the sink and scrubbed. When dry the case was bent carefully back into shape. A Roberts set donated a battery connector and away she went.

I've tested several components on it having measured them for comparison on other equipment and the TF2700 seems to be working very well.

Andrew

[pwdrive]

Nice one Andrew, handy instument to have.

Lawrence.

[Mark R]

Nice one Andrew,
I have a type one bridge by Marconi. It came in really useful when I did the Graves Aerial.

cheers Mark

[AlanBeckett]

Andrew,
I've got one of these, and also the similar Advance one. In fact they're so similar you wonder who copied which one - see attached.
They work very well although I don't find them particularly easy to drive on a completely unknown component.
I've got a Manual and a scan if you need info.
Alan

   

[Yorkie]

The before and after pics of the front panel are impressive Andrew - it's scrubbed up nicely!

I often wonder how much this sort of gear cost when new, especially when adjusted for inflation. Very pricy indeed I imagine. Test gear is invariably very well designed and constructed, as befitted the use to which it was put. I can understand the fascination it has for those who enjoy collecting and restoring it, often putting it to good use too.

[Mark R]

Alan can you put a copy in the archive?

cheers Mark

[AlanBeckett]

Mark,
No problem. I'll have a look at my current scans and possibly do them again.
Alan

[Alistair D]

It is interesting to note that the Farnell claims to be an impedance bridge rather than an LCR meter. For an impedance bridge to work it must be able to correctly measure the resistance, capacitance and inductance of any component connected to it. Am I missing something?

Al

[AlanBeckett]

Al,
It's Advance not Farnell.
I don't think you're missing anything, it's just terminology. Although I haven't got any data on the BR1 as far as I can tell they do exactly the same thing.
Alan

[Skywave]

If it is described as an 'impedance bridge' then I would expect it to measure - and report - impedance. So I would expect the result of the measurement to be in the form |Z| and phase angle or two components: one real and one imaginary (or quadrature, if you prefer that terminology), and the frequency of that measurement being known as well. And that last requirement also implies that the frequency can be adjusted over a known range, ideally a large one.

Al.