Can you wind your own Repanco DRR2 coil?

[trsomian]

I suspect that the coupling on a ferrite rod is good enough that it would matter. I remember that my Philips electronic kit many years ago used to mount the ferrite rod with two twists of wire, but the instruction was that the insulated wire be not stripped back at the ends and the copper must not touch. Presumably because the short circuit turns if they touch would affect something.

Having never seen a DRR2 coil, I didn't know they were air cored

I believe Repanco still exist (albeit as Repanco Bartlett), so may be they are missing a trick by not remaking them

[kalee20]

They're not air cored - there is a screw-adjustable slug in the middle.

[KeithsTV]

All the DRR2s I have are air cored although the formers are threaded.

Keith

[kalee20]

Interesting then, Keith!

I had several new DRX1 and DRR2 coils a few years ago, but I sold them all (on this Forum). Definitely on a threaded former, but you've put doubt in my mind about the trimmer slug! I was thinking that I'd seen a 1-V-1 circuit using DRX1 for the aerial and DRR2 between RF amp and detector - in which for 2-point alignment you'd want at least one of the coils to be adjustable. So maybe the wish was father to the thought!

[David G4EBT]

The one that I borrowed from a chum was in its original box, had never been used and was complete with the (very poor) original Repanco circuit sheet, an annotated copy of which I attached at post #10 above. It didn't have a core, though as Keith says, the former is threaded. The circuits don't used the symbol for a cored coil, but they're so poorly drawn that it isn't much to go by.

The that inductances I measured on the windings of the coil without a core corresponded to those on the maker's data sheet.

[VT FUSE]

Had lots of these as a kid trying to find out if Transistors or valves were better but ended up with lots of dead Ge and a few battery valves inc acorn types with over Volted fil's.
Never had one supplied with a core occupying the early Bakelite or later polystyrene former however.
Ii is quite correct that they were threaded and can remember trying various grades of cores in experiments but they were always good performers without.

[Heatercathodeshort]

The incredible DRR2 coil can be seen in all it's glory here.

https://www.youtube.com/watch?v=ehbqYw1jXd0

[M0FYA Andy]

I think the former is a standard 'Aladdin' type, so with provision for an iron dust core, but not fitted in this case.
I'm not sure when the Aladdin former was introduced, but they are certainly common in the WW2-era equipment I'm familiar with.

[G8HQP Dave]

I have a pair of Repanco coils (RF and regenerative detector). I'm not sure how similar the regen coil is to the DRR2, but it could be identical. They have no cores. With trimmer caps to adjust for circuit strays they match well enough to allow signal reception.

[G0HZU_JMR]

One way to 'capture' the characteristics of the various windings (and how much they interact/couple) would be to measure the whole thing using a multiport VNA. It would then be possible to try and create an equivalent model with a view to eventually winding a real copy that matched the original VNA data (across the whole frequency band) as closely as possible. Maybe this is overkill but these days lots of people have access to a decent VNA and only one person has to do this initial VNA measurement anyway.

[VT FUSE]

Jeremy,that is a really clever point you make,I thought a while back that if what you suggest was done the replication (less the Aladdin former)should not be beyond do-able?

My thought was that a dust iron toroid core such as T80-3 or FT114-61 ferrite
could make a decent inductor to replace the venerable DRR2.
Experiments using 15x0.05 (15/44 ) Litz around 5 years ago did work well but loose coupling of coupling/reaction winding was a faff.

Wonder if anybody suitably equipped with a multiport VNA,time on their hands and access to a DRR2 would be willing to do the measurements?

[M0FYA Andy]

Why less the Aladdin former?
Although I guess they probably aren't made any more, they do turn up, or one can be recovered from another unwanted coil.

[Anthony Thomas]

Talking of winding coils and aladin formers, last time I needed formers to make plug in coils I bought some from a company called "Isoplethics" in the UK. Sorry but I do not know if they exist any longer.

The former that I obtained were Octal and B9a not the Aladin formers mentioned.

[VT FUSE]

Andy- when I do come across Aladdin formers they make me think of your sort of kit and R1155 bfo? coils so are carefully put away since the large style rarely come up intact these days (at least not down this way)

Anthony-sadly Tim the proprietor of Isoplethics died a few years ago,I did try his plug in coil formers but the octal ones were large and deformed with age.

[Anthony Thomas]

Originally Posted by VT FUSE

Anthony-sadly Tim the proprietor of Isoplethics died a few years ago,I did try his plug in coil formers but the octal ones were large and deformed with age.

This I could imagine being the case because "two pack" plastics often harden and change over the years.

My next attempt at plug in coils might be to use B9A plugs with the inductors wound onto small toroids fastened with small cable ties to the B9A plugs.

[VT FUSE]

The reason that I tried toroid cores and the types mentioned,is that my aim was to achieve the tight selectivity of the DRR2 and also a desire to achieve a half decent "Q" in the attempt.

The 2" Litz leadouts were painted with colours to match the tags of the REP coil.
I do not imagine that anyone is likely to do a production run of wave wound near copies of the originals, especially using rare Aladdin formers, however, Litz wound toroids are not that unachievable.

[radioman]

OK, daft question time... What exactly is an Aladdin former ?
Is it just a standard cylindrical type ?

Andy

[ms660]

Aladdin was the maker, yes, cylindrical former, nothing special.

Lawrence.

[radioman]

Thanks Lawrence, despite having been building circuits for the last forty years, it's not a name or description I remember seeing in any of the suppliers catalogues.

Cheers,
Andy

[ms660]

Neosid (Denco) formers were another popular choice.

Lawrence.