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Old 14th May 2021, 1:09 am   #1
VooDoo_Pete
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Question PCMA001S Variable Inductor Coil Identification/Replacement?

Picked this up off eBay... I was intending to use it for spares to keep my other one I fixed last year going, but thought I'd at least try and save it before condemning it to the spares box.

Could someone explain how I'm meant to know the value of a variable inductor coil/can like this please?

For the life of me I can't seem to find the info, I've searched and looked at every schematic/wiring diagram and book I can find.

Should I just know or do you determine the value from the schematic or is it a set value and you don't have to over think it?

I feel really dumb asking, but I genuinely don't know or understand it!

Any idea where I can source a replacement?

Would appreciate any advice, info and explanation... Thanks!
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Old 14th May 2021, 7:51 am   #2
Jon_G4MDC
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

T7, It seems to be a 10.7MHz IF Transformer with coupling winding.
Part of the SSB IF / demodulator feed.

It should be possible to deduce the winding connections from the trackwork and then look in catalogues (Toko etc) for something that matches. Or someone here might have the parts list if you are lucky! These sets have come up before.
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Old 14th May 2021, 8:11 am   #3
SiriusHardware
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

An important detail in the OP is that VP has another one of these. If so, it may be possible to look at the corresponding part in the original one and read the manufacturer (Toko's?) part number which is often stamped in a circular ring around the top of the can.

Just having that number would be a start: Then would begin the worldwide search for a replacement, should one still exist somewhere. If you can't find one maybe there are old Toko data sheets which state the electrical characteristics.
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Old 14th May 2021, 9:06 am   #4
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

If the manufacturer's part number is not stamped on the top of the coil it may be printed in black down one of the sides of the can (on the corresponding coil on the working set).
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Old 14th May 2021, 11:05 am   #5
Jon_G4MDC
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Haha well done Sirius_HW. I missed that obvious point didn't I!

I think that coupled winding is going off to a detector for AGC +Smeter but I didn't look in any detail.
Hopefully fairly non-critical.
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Old 14th May 2021, 11:20 am   #6
VooDoo_Pete
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Post Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Quote:
Originally Posted by Jon_G4MDC View Post
T7, It seems to be a 10.7MHz IF Transformer with coupling winding.
Part of the SSB IF / demodulator feed.

It should be possible to deduce the winding connections from the trackwork and then look in catalogues (Toko etc) for something that matches. Or someone here might have the parts list if you are lucky! These sets have come up before.
Quote:
Originally Posted by SiriusHardware View Post
An important detail in the OP is that VP has another one of these. If so, it may be possible to look at the corresponding part in the original one and read the manufacturer (Toko's?) part number which is often stamped in a circular ring around the top of the can.

Just having that number would be a start: Then would begin the worldwide search for a replacement, should one still exist somewhere. If you can't find one maybe there are old Toko data sheets which state the electrical characteristics.
Quote:
Originally Posted by SiriusHardware View Post
If the manufacturer's part number is not stamped on the top of the coil it may be printed in black down one of the sides of the can (on the corresponding coil on the working set).
Quote:
Originally Posted by Jon_G4MDC View Post
Haha well done Sirius_HW. I missed that obvious point didn't I!

I think that coupled winding is going off to a detector for AGC +Smeter but I didn't look in any detail.
Hopefully fairly non-critical.
Sorry, thought I'd included that info... the can/coil in the other radio only has HTX-456 stamped in black on it, Was the first thing I did and then started searching without any luck!

It's roughly 7mmx7mmx12mm or so...

Is it actually a Variable inductor coil?
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Old 14th May 2021, 2:18 pm   #7
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Yes definitely. Probably why it's been taken out.

Phantom twiddler probably broke the slug. It's in a place that is probably the very last thing that needs adjusting, ever, in the whole life of the radio.
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Old 14th May 2021, 2:55 pm   #8
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

It a pity that Cirkit are not still around. There is a 7mm Can 10.7MHz IF transformer in one of their lists that I would consider a candidate. 119AC30099R

It has the turns ratios as shown and an internal resonating capacitor. I reckon it would be worth a punt but I have no idea where you might get one now.

Cirkit are long gone.
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Old 14th May 2021, 6:23 pm   #9
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

I had an idea, I have a cybernet with a PTBM131A4X circuit board and they are virtually the same as the Nato PCMA001S. Baycliffe Corporation made all of those boards after Kyocera bought Cybernet for their research and development division. The CB division was hived off, contracts honoured and then it was full scale cheapening the whole process. Anyway, the coil in question is a Toko and marked with 07MA 014N 24VG... Hope that helps.
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Old 14th May 2021, 9:03 pm   #10
VooDoo_Pete
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Quote:
Originally Posted by Jon_G4MDC View Post
It a pity that Cirkit are not still around. There is a 7mm Can 10.7MHz IF transformer in one of their lists that I would consider a candidate. 119AC30099R

It has the turns ratios as shown and an internal resonating capacitor. I reckon it would be worth a punt but I have no idea where you might get one now.

Cirkit are long gone.
I'll see if searching the code brings up something...

Last edited by VooDoo_Pete; 14th May 2021 at 9:22 pm. Reason: Info already posted...
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Old 14th May 2021, 11:45 pm   #11
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Bonex / BEC Distribution maybe still around. Or J.A.B. Electronics

These were the main UK Stockists of Toko coils etc. after the demise of Cirkit & Mainline Electronics concentrated on their takeover of Greenweld / resurrection of Jackson Bros.

However I think all these Toko coils are now obsolete, as they are now classed as 'old' technology.

You may well also find that custom parts were used in these CB's, although there may be similar ones in their 'standard' ranges
Note: It is actually a (resonant) IF Transformer, rather than just a variable, from looking at schematic. So need something with the same turns ratio, as well as being designed to be resonant with the same external capacitors.

CB Parts suppliers like SJ Tonks, Knights, Nevada, Truck King etc. used to be able to supply many of the more specialised parts, but not sure how many are still around - Knights are: https://www.kcb.co.uk/ and maybe Truck King).

Otherwise, if it was used on other Cybernet chassis, then might be able to obtain from a scrap unit - There were so many wrecked CB's back in the 80's that most people repairing these had their own graveyard boxes of these to salvage parts from.

A copy of the Cybernet Export Manual may be helpful.
http://www.radiomanual.info/schemi/V...ew_version.pdf
http://www.radiomanual.info/schemi/V...ld_version.pdf

And a manual with fuller technical details on the PCM001S (But only says SSB Detector for T7 - no actual part number): https://www.manualslib.com/download/...Star-2200.html

But maybe a SAMS FotoFacts manual from CB City in USA etc. is probably the most detailed, having many pictures and maybe parts lists:
http://cbcintl.com/docs/sams.pdf

Last edited by ortek_service; 15th May 2021 at 12:12 am.
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Old 15th May 2021, 12:15 am   #12
G0HZU_JMR
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

My advice would be to register at Transmission1 and ask if anyone can pull one from a scrap CB board for you.

https://www.transmission1.net/

There will be loads of CB repair people on there and I'd expect someone will able to find the correct part for your particular CB board (Nato 2000?).
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Old 15th May 2021, 12:22 am   #13
John KC0G
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Re. post #10, I am pretty sure that JAB Electronics have them, but you will not find it by search. I think that they have a typo and list the 119AC30099R as LL9AC30099R. One from a scrap unit is a better idea.
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Old 15th May 2021, 5:48 am   #14
VooDoo_Pete
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Thumbs up Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Quote:
Originally Posted by ortek_service View Post
Bonex / BEC Distribution maybe still around. Or J.A.B. Electronics

These were the main UK Stockists of Toko coils etc. after the demise of Cirkit & Mainline Electronics concentrated on their takeover of Greenweld / resurrection of Jackson Bros.

However I think all these Toko coils are now obsolete, as they are now classed as 'old' technology.

You may well also find that custom parts were used in these CB's, although there may be similar ones in their 'standard' ranges
Note: It is actually a (resonant) IF Transformer, rather than just a variable, from looking at schematic. So need something with the same turns ratio, as well as being designed to be resonant with the same external capacitors.

CB Parts suppliers like SJ Tonks, Knights, Nevada, Truck King etc. used to be able to supply many of the more specialised parts, but not sure how many are still around - Knights are: https://www.kcb.co.uk/ and maybe Truck King).

Otherwise, if it was used on other Cybernet chassis, then might be able to obtain from a scrap unit - There were so many wrecked CB's back in the 80's that most people repairing these had their own graveyard boxes of these to salvage parts from.

A copy of the Cybernet Export Manual may be helpful.
http://www.radiomanual.info/schemi/V...ew_version.pdf
http://www.radiomanual.info/schemi/V...ld_version.pdf

And a manual with fuller technical details on the PCM001S (But only says SSB Detector for T7 - no actual part number): https://www.manualslib.com/download/...Star-2200.html

But maybe a SAMS FotoFacts manual from CB City in USA etc. is probably the most detailed, having many pictures and maybe parts lists:
http://cbcintl.com/docs/sams.pdf
Thanks for the info, SJ Tonks and Truck King are long gone too...

I've got copies of the export manual, 2200 Service Manual etc

SAMS don't cover the PMCA001S as it was after they stopped from what I've read, they reference/offer the Cybernet Export Manual instead.
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Old 15th May 2021, 5:51 am   #15
VooDoo_Pete
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Default Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Quote:
Originally Posted by G0HZU_JMR View Post
My advice would be to register at Transmission1 and ask if anyone can pull one from a scrap CB board for you.

https://www.transmission1.net/

There will be loads of CB repair people on there and I'd expect someone will able to find the correct part for your particular CB board (Nato 2000?).
I'm on Transmission1 and have a thread up asking for advice/help there too.
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Old 15th May 2021, 5:52 am   #16
VooDoo_Pete
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Thumbs up Re: PCMA001S Variable Inductor Coil Identification/Replacement?

Quote:
Originally Posted by John KC0G View Post
Re. post #10, I am pretty sure that JAB Electronics have them, but you will not find it by search. I think that they have a typo and list the 119AC30099R as LL9AC30099R. One from a scrap unit is a better idea.
I found some on another site while searching and ordered, will see if they turn up...

If not I'll get a refund through PayPal and order some from JABS instead!
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