Pye Radiotelephone Crystal ilter IF unit. - UK Vintage Radio Repair and Restoration Discussion Forum

TonyGlazier · 1st Mar 2023, 4:02 pm

I wonder of anyone can identify this Pye IF unit with crystal filter?

I have always expected they are are a 10.7 MHz and about 15 kHz wide.

I have always expected they were used in one of the common base station units about 1980 when they started using semiconductors.

i NEED TO COME BACK AND HAVE ANOTHER GO AT ADING A PHOTO!

Cobaltblue · 1st Mar 2023, 4:54 pm

Hi Tony and welcome to the forum.

There is a guide to posting pictures here:

https://www.vintage-radio.net/forum/...ad.php?t=77650

Hope that helps.

Cheers

Mike T

Bazz4CQJ · 1st Mar 2023, 5:14 pm

Yes, post a pic! A few weeks ago, I used my oscillating saw to open up a 455kHz filter from a Pye Vanguard. About the size of pack of 20 cigarettes, I was expecting crystals inside, but all I got was eight lousy ferrite pot cores

.

But, I did manage to open it without causing any damage, so I might yet have a use of that in future.

B

CambridgeWorks · 1st Mar 2023, 6:26 pm

Bazz, 455KHz block filters were LC up until latter days of Westminster.
I once saw the person aligning them prior to the can being sealed and he had a mind numbing job!
Then, all they had was a Murata or similar tiny filter inside the same size can.
You could tell by how light they were and the hollow sound if tapped.
Example part number with say 7V455L indicated Very narrow (ONLY!) +/- 7.5KHz.
N was Narrow, +/- 15KHz and S was Super narrow +/- 3.75KHz
Carrier frequency channel spacing is: N, 50KHz, V 25KHz and S 12.5KHz.
In VERY early days, 100KHz channel spacing was normal.
As demand grew, channel spacing was halved and new channels interleaved with existing ones. But, EVERYONE had to alter their bandwidth to remain compatible.
VHF airband is a different matter, 8.33KHz channel spacing being the last change, but not relevant here with Pye filters.
Rob

Bazz4CQJ · 1st Mar 2023, 6:37 pm

Yes, I think this one was a 50kHz beast and I should have guessed there were no crystals. To stop the pots moving around there was the dreaded black spongey foam packed on either side, and that was well on it's way to becoming goo!

I'm in the process of building a Haigh-Matthews wobbulator and I thought that old filter would give me something to practice on

. I said it was 8 cores, but it's actually 10.

B

Jon_G4MDC · 1st Mar 2023, 8:07 pm

I suspect we have gone from an IF Board with a Cathodeon (probably) Crystal Filter - which can be 2 pole 4 pole or 8 pole depending on Mobile Base etc to the 455kHz IF Filter which was usually chassis mounted and based on pot cores or later ceramic - AFIK.

All the foregoing gen about those is good but the usage of the 10.7 MHz crystal filters will also be worth examining.

Check the various W15 parts lists...

The Narrow 12.5 kHz Filter was not the same PN between AM and FM.

It looks like the wider ones were the same PN but in FM sets only the 4pole ones were used.

I wonder why? It will be interesting to see what the Home Office R8AM/HO receivers used. Probably the 8 pole ones?

Later addition - wasn't there an R8AM/GA - for Aeronautical use?

Bazz4CQJ · 1st Mar 2023, 8:26 pm

Quote:

Originally Posted by Jon_G4MDC

I suspect we have gone from an IF Board with a Cathodeon (probably) Crystal Filter - which can be 2 pole 4 pole or 8 pole depending on Mobile Base etc to the 455kHz IF Filter which was usually chassis mounted and based on pot cores or later ceramic - AFIK.

Yes, we need the op to post a picture.

B

1st Mar 2023, 4:02 pm	#1
TonyGlazier Diode Join Date: Mar 2023 Location: London, UK. Posts: 2	Pye Radiotelephone Crystal ilter IF unit. I wonder of anyone can identify this Pye IF unit with crystal filter? I have always expected they are are a 10.7 MHz and about 15 kHz wide. I have always expected they were used in one of the common base station units about 1980 when they started using semiconductors. i NEED TO COME BACK AND HAVE ANOTHER GO AT ADING A PHOTO!

1st Mar 2023, 4:54 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,857	Re: Pye Radiotelephone Crystal ilter IF unit. Hi Tony and welcome to the forum. There is a guide to posting pictures here: https://www.vintage-radio.net/forum/...ad.php?t=77650 Hope that helps. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

1st Mar 2023, 5:14 pm	#3
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,934	Re: Pye Radiotelephone Crystal ilter IF unit. Yes, post a pic! A few weeks ago, I used my oscillating saw to open up a 455kHz filter from a Pye Vanguard. About the size of pack of 20 cigarettes, I was expecting crystals inside, but all I got was eight lousy ferrite pot cores . But, I did manage to open it without causing any damage, so I might yet have a use of that in future. B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.

1st Mar 2023, 6:26 pm	#4
CambridgeWorks Nonode Join Date: Jun 2010 Location: Spalding, Peterborough, Cambridgeshire, UK. Posts: 2,858	Re: Pye Radiotelephone Crystal ilter IF unit. Bazz, 455KHz block filters were LC up until latter days of Westminster. I once saw the person aligning them prior to the can being sealed and he had a mind numbing job! Then, all they had was a Murata or similar tiny filter inside the same size can. You could tell by how light they were and the hollow sound if tapped. Example part number with say 7V455L indicated Very narrow (ONLY!) +/- 7.5KHz. N was Narrow, +/- 15KHz and S was Super narrow +/- 3.75KHz Carrier frequency channel spacing is: N, 50KHz, V 25KHz and S 12.5KHz. In VERY early days, 100KHz channel spacing was normal. As demand grew, channel spacing was halved and new channels interleaved with existing ones. But, EVERYONE had to alter their bandwidth to remain compatible. VHF airband is a different matter, 8.33KHz channel spacing being the last change, but not relevant here with Pye filters. Rob __________________ Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd Last edited by CambridgeWorks; 1st Mar 2023 at 6:28 pm. Reason: added second sentence

1st Mar 2023, 6:37 pm	#5
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,934	Re: Pye Radiotelephone Crystal ilter IF unit. Yes, I think this one was a 50kHz beast and I should have guessed there were no crystals. To stop the pots moving around there was the dreaded black spongey foam packed on either side, and that was well on it's way to becoming goo! I'm in the process of building a Haigh-Matthews wobbulator and I thought that old filter would give me something to practice on . I said it was 8 cores, but it's actually 10. B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. Last edited by Bazz4CQJ; 1st Mar 2023 at 6:42 pm.

1st Mar 2023, 8:07 pm	#6
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Pye Radiotelephone Crystal ilter IF unit. I suspect we have gone from an IF Board with a Cathodeon (probably) Crystal Filter - which can be 2 pole 4 pole or 8 pole depending on Mobile Base etc to the 455kHz IF Filter which was usually chassis mounted and based on pot cores or later ceramic - AFIK. All the foregoing gen about those is good but the usage of the 10.7 MHz crystal filters will also be worth examining. Check the various W15 parts lists... The Narrow 12.5 kHz Filter was not the same PN between AM and FM. It looks like the wider ones were the same PN but in FM sets only the 4pole ones were used. I wonder why? It will be interesting to see what the Home Office R8AM/HO receivers used. Probably the 8 pole ones? Later addition - wasn't there an R8AM/GA - for Aeronautical use? Attached Thumbnails Last edited by Jon_G4MDC; 1st Mar 2023 at 8:13 pm.