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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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31st May 2011, 8:23 pm | #1 |
Nonode
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,085
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Unidentified Coils
I have two coils in a small square box. The box is marked in ink C.O.M.1.
At one end there are four tags. They are colour coded red, white, green & black by paint on the ends of the paxolin tube. I guess they are oscillator coils. What do you think? Last edited by Neil Purling; 31st May 2011 at 8:31 pm. Reason: Added image |
31st May 2011, 9:26 pm | #2 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,194
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Re: Unidentified Coils
Hi Neil, they look very similar to Wearite "P" coils (but may in fact be Colvern) which usually had a red sleeve on one of the tags denoting the grid connection, the tag 180deg away was the ground connection.
The opposite pair of tags was for the primary winding. An inductance bridge will show you the "L" value and you can then calculate the wave range with a typical tuning cap of 40pf to 500pf. The "O" in the spec would tend to make one think oscillator, but they could still be used as aerial coils or HF transformers. Ed |
2nd Jun 2011, 6:42 am | #3 |
Nonode
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,085
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Re: Unidentified Coils
I have looked on the Web for Colvern coils. However I have only seen examples of pre-war catalogues. I really need to see a post-war catalogue of their products.
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5th Jun 2011, 4:50 pm | #4 |
Nonode
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,085
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Re: Unidentified Coils
I added 5 turns to the bottom of one winding to make up a coil for the 'electron-coupled' circuit.
It does work and the receiver will oscillate, as it does with the home made coil. So, I have proved a alternate use for what may have been a oscillator coil. |
5th Jun 2011, 9:08 pm | #5 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,194
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Re: Unidentified Coils
Hi Neil, most of these coils will have a tuned winding which will have a tuning cap connected across it, and cover a certain wave range.
Aerial and HF transformer coils will cover the "standard" bands. Oscillator coils will cover an offset (by the IF frequency) of these bands. The non-tuned winding or windings will be dependant on he set and application of the coil. The main winding is still useful in sets such as you are building and will probably have a better Q than any you may wind yourself. Ed |
30th Jul 2011, 9:08 pm | #6 |
Diode
Join Date: Jul 2011
Location: Preston, Lancashire, UK.
Posts: 8
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Re: Unidentified Coils
Didn't the Wearite coils fix by using a metal bar through the coil and a screw up into it? I know the P type did. I notice that these use an L bracket.
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