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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 24th Nov 2019, 1:09 pm   #1
Martin G7MRV
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Default Toko RF/IF transformer colour code?

Hi All,

I believe this is fairly standard colour code but im at a loss to find details of it!

I have an LW receiver (actually a marine RDF unit) that im going to attempt to pull up in frequency a little, as it currently covers 180-400kHz, which is a little low for the remaining aero beacons, which go up to 550kHz.

Without totally dismantling the unit, there are three RF/IF transformer cans accessible (a 4th is hidden under a shielding plate with no access hole, whereas the yellow one which is also under the plate has a hole to adjust through)

These are Toko cans coloured Red, Orange, and Yellow.

If someone could confirm the colour code for me, that would be a great help!

Cheers
Martin

p.s. I appreciate that this is likely to have a 455/470kHz IF!
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Old 24th Nov 2019, 1:13 pm   #2
ms660
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Default Re: Toko RF/IF transformer colour code?

Some info here:

http://joefreeman.weebly.com/uploads..._coil_data.pdf

Lawrence.
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Old 24th Nov 2019, 1:38 pm   #3
Martin G7MRV
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Default Re: Toko RF/IF transformer colour code?

Quote:
Originally Posted by ms660 View Post
Absolutely perfect! (wish now i'd kept my old Bonex catalogues...)

It seems everything is 'off-the-shelf' in this, no house marked parts, all normal commercial part numbers, so from that list (and deciding to take the thing apart!) ive identified the orange, yellow, and black (hidden) coils as 1st, 2nd and 3rd IF(det) respectively. That leaves the red as oscillator i guess. Cant find its part number in those lists though (YMOS2A783) but its very hard to read so I might have it wrong.

It looks then like its a 468kHz IF
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Old 24th Nov 2019, 1:48 pm   #4
Dave757
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Default Re: Toko RF/IF transformer colour code?

Hi Martin,

I wouldn't have thought there was much still copiable in the UK
above 520.

Highest I have heard in the last year or two here in Scratby is
BSW on 521.

Have you done any better up there in Yorkshire?

Kind regards
Dave G0ELJ
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Old 24th Nov 2019, 1:53 pm   #5
Martin G7MRV
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Default Re: Toko RF/IF transformer colour code?

Ive been looking at various lists, and TBH other than Lichfield, I cant find any listed above 440kHz, so it might not be worth trying to pull the radio much beyond that. Of course, going much further runs the risk of ploughing into the IF anyway.

This is not sensitive enough for any serious NDB Dxing anyway, its more just for a bit of fun! I can get Finningly, Leeds-Bradford and Sherburn on it! (Sherburn was inevitable as im under the circuit!)
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Last edited by Martin G7MRV; 24th Nov 2019 at 2:02 pm.
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Old 24th Nov 2019, 2:42 pm   #6
Dave757
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Default Re: Toko RF/IF transformer colour code?

Hi Martin,

There are plenty of beacons above 440kHz to make this a worthwhile
proposition although maybe not for much longer. Lichfield beacon LIC
disappeared some years ago.
I have received 36 beacons above 440kHz in the last couple of years,
so maybe a better aerial would help,- I use a square loop with sides
roughly 1 metre in length.

Kind regards
Dave
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Old 24th Nov 2019, 4:28 pm   #7
Philips210
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Default Re: Toko RF/IF transformer colour code?

Quote:
Originally Posted by ms660 View Post
Thanks Lawrence. That's a very comprehensive set of data and also useful to see data on their moulded VHF coils.

Regards,
Symon
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Old 24th Nov 2019, 6:00 pm   #8
Martin G7MRV
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Default Re: Toko RF/IF transformer colour code?

Quote:
Originally Posted by Dave757 View Post
Hi Martin,

There are plenty of beacons above 440kHz to make this a worthwhile
proposition although maybe not for much longer. Lichfield beacon LIC
disappeared some years ago.
I have received 36 beacons above 440kHz in the last couple of years,
so maybe a better aerial would help,- I use a square loop with sides
roughly 1 metre in length.

Kind regards
Dave
I have used a tuned 1m square loop with my FRG-100 to receive many beacons, but this particular unit is a handheld, self contained DF receiver, no provision for external antennas. Its more of a novelty item these days, since theres no coastal beacons for boats anymore, so I might just leave it as it is.
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