Odd looking detector in crystal set

[retailer]

I've had this crystal set for around 30yrs and the cat's whisker type crystal detector has always intrigued me, it is unlike any I have seen before and could be described as a deluxe version of the traditional cat's whisker detector. The complete detector has a pair of banana plugs fitted and plugs into the front panel of the crystal set, the lump of galena is held in a removable holder that slots into the top - the knob at the front is rotated, this causes a cat's whisker to move in a circular and up and down motion until a sensitive spot is found for listening. I did an internet search a few years ago and came across only one other example, where as I saw dozens of the traditional type that uses a small pivoting probe to select a sensitive spot on the galena, has anyone seen these types before, only finding one other example I assume they are rare would this be because they were costly or because they were a failure and did not work as well as one imagined they would, I certainly have not managed to get a peep out of mine using around 4 meters of wire as an antenna, I'm located around 12 Km from an ABC am transmitting tower.

[60 oldjohn]

Never seen one like that, the nearest I can find is the E'xcentro mad by Horne brothers around 1923. https://www.google.co.uk/search?q=l%...w=1366&bih=599 Any indication of country of manufacture?

I have just seen the H in your picture, wonder if it was another style of detector from Horne .

This? https://picclick.fr/D%C3%A9tecteur-g...942885080.html


John.

[newlite4]

You would need a much longer aerial say 25 metres and a good earth to get satisfactory results.
Neil

[Walterh]

That's a Friho. I'm having the matching crystal set - without the detector.

For more details see in RM.org https://www.radiomuseum.org/r/friho_friho_20.html

Walter

[paulsherwin]

Originally Posted by newlite4

You would need a much longer aerial say 25 metres and a good earth to get satisfactory results.
Neil

I don't know - if he's only 12km from a big transmitter he may get acceptable results from much less. I would temporarily replace the detector with a Ge diode like an OA81 and see what the reception is like with that.

[lesmw0sec]

I'd agree. When at boarding school near London our crystal sets with minimal aerials were so loud you could hear the programme with the headphones hanging on the bedhead!

[retailer]

Amazing what you find when you do a proper search - I should have guessed there would have been an example on the famous Jogis Röhrenbude web site, it's official name in German is Aufsteckdetektoren which translates to "for plugging in detector". The web site owner describes the detector and laments the passing of broadcasts that can be received by the detector so I assume he is talking about AM radio the link is:- http://www.jogis-roehrenbude.de/Dete...empfaenger.htm

Google translate does a good job of translating the web page.

I must admit I did not spend a lot of time with the set it uses those horrible headphones that always pull out what hair one has left each time they are taken off. I do have quite a few older germanium diodes from the OA range and also GEX types - I'll follow Paul's suggestion

[retailer]

I spent a bit of time with the crystal set and determined that the cord on the old headphones (Stirling) was faulty - both sides being affected, the cord is the usual cloth covered stuff, it looks ok with almost no frayed bits but is open circuit. All of the connections and termination points have been wound with a black thread to which has had some sort of glue/wax applied to it. The fault is probably in the central Y point connection, not sure if the earpieces were series or parallel connected. With the headphones known to be faulty I connected an old crystal earpiece to the set and was able to easily set the detector to a sensitive spot by turning the knob at the front, for comparison I connected an OA79 via a pair of banana plugs it was clearly louder by about 25-30%. Antenna was a length of hookup wire around 10 meters long, about 5 meters from the bench across to the door and the rest was simply looped around a fence post to keep it taught. The local Gov radio station ABC swamped all of the other stations which is about what I expected.

The detector did surprise me as I did not really expect it work as well as it did, prior to the listening test I checked it with the diode test range on my Fluke 87 and found that while it did provide some rectification it conducted in both directions with one way being better than the other.

[Stylo N M]

Hi,
you can exsperiment in many different ways, with crystal sets and it's fun.

Try adding an extra tuning capacitor, say around 320pF or any little tuning capacitor you might have to hand, in line with the incoming aerial feed, this will help to prevent one station swamping over anouther.

Of course the downside to this is, anything extra you add to improve selectivity, will cost you in a certain amount of sound reduction.

Paul.

[60 oldjohn]

Originally Posted by retailer

I spent a bit of time with the crystal set and determined that the cord on the old headphones (Stirling) was faulty - both sides being affected, the cord is the usual cloth covered stuff, it looks ok with almost no frayed bits but is open circuit. All of the connections and termination points have been wound with a black thread to which has had some sort of glue/wax applied to it. The fault is probably in the central Y point connection,

My experience of faulty headphone leads is , it's very probable that the two metal ends, the wire breaks where black thread and metal start. Worth trying before trying to disturb the Y junction. BTW the phones will be wired in series. The wires may be of the tinsel type a proper S*d to deal with.



John.