Mode Zero

Looking at the data in the Archive section, I see that the Remcon 12-channel has a full set of instructions, including circuit diagrams and PCB images. The receiver PCB is particularly interesting with its lands all being straight lines - this would be easy to recreate on a small CNC milling machine.

So I got to wondering if I could make a complete receiver, either using Tobe's reed bank or a made-up one.

Many components, like resistors and caps, are easy to source nowadays. The coils are specified, so quite possible to build. There should be modern transistor equivalents for all the old specifications. But a 5:1 transformer and the IF cans look as if they could be a problem...

Does anyone know:

• where one might get a miniature 5:1 transformer?
  what the specification of the IF cans is?
  whether matching cans are still available?

IF cans

2 or 3days ago Ali express served up a 'shop' titled Bohinda Inductive Coil Store or similar.

I've just searched and drew a blank but Bohinda is correct.

Amongst every style of if/rf coil you could imagine were 7mm and 10mm 450khz IF cans.

Of course I didn;t think anyone would be interested!

Just did a quick search on bohinda from the Aussie(?) site and turned up a heap of stuff. E.g.

"AU$9.09 | 5 Radio AM IF filter 450kHZ carrier oscillation adjustable inductance coils"

Happy hunting

Ah - thanks for the rapid response! That looks a possible source...

My main concern at the momen is that I don't know what the original spec that Remcon used was. Their internal wiring appears to be similar, but they are colour-coded, so I assume that they have differences - perhaps to do withtheferrite slug tuning? Is 450kHZ the standard for this frequency?

The "standard" IF tuning is 455KHz, but some older British sets used 470KHz. You can tell which you need by subtracting the Rx crystal frequency from the Tx Frequency.

If you are ordering new crystals - or using Futaba - go for 455KHz.

The usual colour coding was Yellow for 1st coil, White for second and Black for 3rd (when using popular Toko coils).

--
Pete

The "standard" IF tuning is 455KHz, but some older British sets used 470KHz. You can tell which you need by subtracting the Rx crystal frequency from the Tx Frequency.

Since I am looking to recreate a Remcon receiver from scratch, I don't have any data about the original IF. And annoyingly the archive document on this site gives no details about it.

This could be an advantage, though. Assuming I have a Red (27.045) crystal in the transmitter, I can pick any receiver crystal to match any intermediate coil that I can obtain. . So, if I can get 450kHZ cans, I should look for a 26.595 MHZ crystal. The IF cans and the receiver crystal frequency will be determined, not by what was original, but by what is on the market today...

As far as I am aware, 470 KHz hasn't been used in ages. All the Futaba (or equivalent) single conversion crystals will be 455 KHz.

I don't recall ever seeing a 27 MHz double-conversion receiver.

I think Grundig used to use an odd IF as well (460 KHz?), but the chances of finding a set of Grundig crystals is almost zero!

If you stick to Futaba, or equivalent, and 455 KHz cans, you should be OK.

--
Pete

I think the old blue brushed aluminium Macgregor receivers with the black end cheeks with white rubber grommets like MR23 were 470khz i.f. but when the “A” series ones came out (blue plastic) they moved over to 455khz. I can clearly remember a 470khz sticker on the boxes.

Ron

Was this it Ron?
viewtopic.php?f=24&t=1607&p=13358

Hi Phil
No, the sticker definitely said 470khz If.
Here’s the manual for the digimac 1plus 1 on crystals.