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Old 16th Sep 2019, 9:37 pm   #1
G3VKM_Roger
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Default 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
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Old 17th Sep 2019, 8:07 am   #2
David G4EBT
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Default Re: Wearite BFO coil?

Donít know if this helps Roger:

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

Good luck in your quest.
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Old 17th Sep 2019, 5:51 pm   #3
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Default 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
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Old 17th Sep 2019, 5:59 pm   #4
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Default 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.
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Old 18th Sep 2019, 6:42 am   #5
G3VKM_Roger
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Default 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
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Old 19th Sep 2019, 11:46 am   #6
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Default 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
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Old 25th Sep 2019, 1:47 pm   #7
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Default Re: Wearite BFO coil?

Quote:
Originally Posted by ms660 View Post
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 Iím still interested in obtaining one.

Thanks

Roger
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