Wearite BFO coil? - UK Vintage Radio Repair and Restoration Discussion Forum

G3VKM_Roger · 16th Sep 2019, 9:37 pm

Hi All,

I have a plug-in BFO unit, which is U/S, fitted in a Coastal Radio 91/MX marine receiver. The 91/MX IF is 470kHz and the single coil was made by Wearite, but unfortunately the type markings are too faded to read. I suspect the coil is O/C but need to lift some of the connections to do a proper continuity test.

However I have not been able to find any info online for a Wearite coil for a BFO application, so I was wondering if anyone had a catalogue or data sheet with more info, probably from the late 40s/early 50s era?

Thanks,

Roger

David G4EBT · 17th Sep 2019, 8:07 am

Don’t know if this helps Roger:

http://vintageradio.me.uk/info/wearite.htm

Good luck in your quest.

G3VKM_Roger · 17th Sep 2019, 5:51 pm

Thanks David, I can't see a BFO coil as such on that page but it helps to know what the various Wearite coils were used for.

73

Roger

ms660 · 17th Sep 2019, 5:59 pm

You won't see a picture of it on the page or shown in the tables but it's described in the text, basically a 1000uH inductor tapped for Hartley osc operation, for an IF of 465kHz a capacitor of 118pF will give a 1kHz beat note.

Lawrence.

G3VKM_Roger · 18th Sep 2019, 6:42 am

You're absolutely right, Lawrence! I had looked at the drawings of the coils and the table. With that info I can probably wind a replacement coil if the original turns out to be O/C.

Many thanks,

Roger

G3VKM_Roger · 19th Sep 2019, 11:46 am

OK, got a little further with the coil problem. Removing the Wearite coil from the chassis reveals the part number is a PO7, an oscillator coil with two windings. One winding appears O/C. No sign of a PO7 on ebay or other sites so does anyone have one in their collection they will sell?

Cheers

Roger

G3VKM_Roger · 25th Sep 2019, 1:47 pm

Quote:

Originally Posted by ms660

You won't see a picture of it on the page or shown in the tables but it's described in the text, basically a 1000uH inductor tapped for Hartley osc operation, for an IF of 465kHz a capacitor of 118pF will give a 1kHz beat note.

Lawrence.

A forum member has very kindly sent me a BFO coil, which I should be able to use in place of the PO7 type, although with some cct mods. If anyone has a PO7 kicking around I’m still interested in obtaining one.

Thanks

Roger

16th Sep 2019, 9:37 pm	#1
G3VKM_Roger Heptode Join Date: Jun 2012 Location: Southeast Norfolk, UK. Posts: 773	Wearite BFO coil? Hi All, I have a plug-in BFO unit, which is U/S, fitted in a Coastal Radio 91/MX marine receiver. The 91/MX IF is 470kHz and the single coil was made by Wearite, but unfortunately the type markings are too faded to read. I suspect the coil is O/C but need to lift some of the connections to do a proper continuity test. However I have not been able to find any info online for a Wearite coil for a BFO application, so I was wondering if anyone had a catalogue or data sheet with more info, probably from the late 40s/early 50s era? Thanks, Roger

17th Sep 2019, 8:07 am	#2
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,761	Re: Wearite BFO coil? Don’t know if this helps Roger: http://vintageradio.me.uk/info/wearite.htm Good luck in your quest. __________________ David. BVWS Member. G-QRP Club member 1339.

17th Sep 2019, 5:51 pm	#3
G3VKM_Roger Heptode Join Date: Jun 2012 Location: Southeast Norfolk, UK. Posts: 773	Re: Wearite BFO coil? Thanks David, I can't see a BFO coil as such on that page but it helps to know what the various Wearite coils were used for. 73 Roger

17th Sep 2019, 5:59 pm	#4
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Wearite BFO coil? You won't see a picture of it on the page or shown in the tables but it's described in the text, basically a 1000uH inductor tapped for Hartley osc operation, for an IF of 465kHz a capacitor of 118pF will give a 1kHz beat note. Lawrence.

18th Sep 2019, 6:42 am	#5
G3VKM_Roger Heptode Join Date: Jun 2012 Location: Southeast Norfolk, UK. Posts: 773	Re: Wearite BFO coil? You're absolutely right, Lawrence! I had looked at the drawings of the coils and the table. With that info I can probably wind a replacement coil if the original turns out to be O/C. Many thanks, Roger

19th Sep 2019, 11:46 am	#6
G3VKM_Roger Heptode Join Date: Jun 2012 Location: Southeast Norfolk, UK. Posts: 773	Re: Wearite BFO coil? OK, got a little further with the coil problem. Removing the Wearite coil from the chassis reveals the part number is a PO7, an oscillator coil with two windings. One winding appears O/C. No sign of a PO7 on ebay or other sites so does anyone have one in their collection they will sell? Cheers Roger