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Old 1st Feb 2020, 8:01 pm   #1
samjmann
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Default What on earth is this?

Hello all.

A friend of mine was helping to clear a shed of a former GPO/BT engineer. During the clearance he found this 'item' amongst masses of electrical/electronic gear. I've no idea what was used for, I'll connect 9V to it and see what happens.

There is only one control which alters the tuning capacitor. This seems to be taken from a MW/LW radio. So I would have thought it works at below 2Mhz. There is no speaker or indicator of any sort, only the tuning control and the on/off switch. The only outside connection is via a length of TV co-ax to a Belling-Lee aerial plug

Whoever made it built it from scratch from basics. The ferrite rod section is unscreened in the top of the case, the lower section is screened by self adhesive foil. All I can think is that it injects a signal into the lead which then connects to something else!

Any thoughts or ideas anyone? Cheers, SJM
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Old 1st Feb 2020, 8:33 pm   #2
Cobaltblue
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Default Re: What on earth is this?

I wonder if it's a home made version of a Seafix.


https://www.radiomuseum.org/r/electr...eafix_200.html


Cheers


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Old 1st Feb 2020, 11:07 pm   #3
samjmann
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Default Re: What on earth is this?

Thanks Mike,

With the shape of the box and handle, perhaps it's just a tuneable RF amp.
So if it's for marine use, Perhaps the cable was attached to the aerial in of a radio in the cabin, you then tuned the radio to a known station, then peaked the box with the control, noted the direction with a compass and then repeated this with another known station. With triangulation could you then work out where you were - roughly?

The Seafix looks easier, and more accurate though!

Cheers, SJM
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Old 1st Feb 2020, 11:15 pm   #4
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Default Re: What on earth is this?

I've no idea what you have, but would be interested to know it the AF11x is OK.
My experience of them is, if it is made in Holland there is a very good chance it does not suffer from Tin Whisker,, yet.


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Old 2nd Feb 2020, 12:31 am   #5
Terry_VK5TM
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Default Re: What on earth is this?

Back when I was doing my Post Office tech training, there was a unit which injected an RF signal into a cable and the handpiece was used to trace the cables location in the wall (ours was two seperate boxes), could this be something similar?
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Old 2nd Feb 2020, 2:48 pm   #6
m0cemdave
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Default Re: What on earth is this?

It looks like there is a ferrite rod in the top part of the box, with 4 connections. Two to the tuning capacitor (apparently balanced) and two to the circuitry, presumably from a coupling coil. It does seem to be a DF unit, with a preamp, to feed a separate receiver.

I wonder if the original builder worked for the RI department, in which case it was probably used for chasing pirates (back in the days when they were all on medium wave, don't ask...)
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Old 4th Feb 2020, 1:54 pm   #7
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Default Re: What on earth is this?

I'll bet it was for top band DF competitions.

I had some contact with the RI outfit in my BT days - they didn't use home made kit !
Their MF/HF stuff was mainly made by Eddystone - for example - the Measuring Set 40A, which was based on the Eddystone 1000 series.
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Old 7th Feb 2020, 5:53 pm   #8
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Default Re: What on earth is this?

R.D.F set for boats as described in Practical Wireless sometime in the 60s I think.
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