Codar CR45 Coils - UK Vintage Radio Repair and Restoration Discussion Forum

DaveG0MXD · 16th Feb 2007, 8:39 pm

I recently acquired an old Codar CR45, but with only one of the green plug-in coils (covers range 3, 160 and 80m bands). Does anyone have information on the winding requirements for the other 4 coils. I have formulated a way of manufacturing coil formers of the correct size and shape, so a set of close-up jpg's of someone elses coils would probably be OK for the two HF bands coils.

I had one of these in the late sixties, and would love to get this one back working on all bands again.

Regards,

Dave G0MXD

Ed_Dinning · 17th Feb 2007, 7:44 pm

Hi Dave, I have a Codar multi band 6; this appears to use a Denco B9A plug in coil from the green range. I suppose this could be a valve coil in my set as opposed to a transistor one as the multi-band 6 has a Mosfet input which is a high impedance like a valve.
These coils sometimes come up on e-bay, or you could see if anyone on the forum has one to spare. It may be possible to experimnet and wind your own, but Denco coils are very compact and efficient.

Ed

DaveG0MXD · 17th Feb 2007, 8:29 pm

Thanks Ed, but I omitted to mention that the coils are all octal-based. I believe that the originals were supplied by Denco, as their early coils were octal based, designed for valve circuits. I have collected a lot of information on the size / shape / etc. of the coils, but have so-far been unsuccessful in obtaining winding details.

The B9A coils were definitely designed for use on transistor circuits. I also used to own a set of them which I used when I built my first two transistor TRF set from a textbook design published c. 1970.

I had also thought of acquiring a set on E-Bay and converting them for use as octal coils (ie: solder an octal plug base onto the 9-pin coil!!). However, this would be a last resort as I am trying for authenticity (and the green coils are etremely rare on E-Bay!).

However, if I get the chance I will try and acquire a Multiband 6, to go with my CR45 and CR70A + PR30 (now fully restored). As you may have guessed, I do like Codar gear, ever since I bought my first one!!

As a next step, I was considering going back to basics, sticking the coil I have on an RF Bridge, and back-calculating the required inductances and turns ratios from that (and the front panel frequency ranges). Unfortunately, I still would not have any wire size information, but it would be a strart.

Unfortunately, it all takes time.

Regards,

Dave G0MXD

Ed_Dinning · 17th Feb 2007, 10:16 pm

Hi Dave, the B9A types were available as both valve and transistor types and superseded the octalsa which I think were only valve types.
If you PM me your address I'll send a p copy of the Denco data I have. This does not appear to have inductance data as the Wearite coils do but it gives the range with a specific cap swing, so this can easily be calculated. Langford -Smith has all the details of how to make coils.
For the lower frequencies something like 35 to 40SWG should suffice and it is not totally necessary to wave wind. Above about 3 MHz it would be better to use a Litz wire, say 7/48 SWG and to wave wind.
Try and use a similar spacing as Denco did between the coils to get the same coupling.
The best piece of kit to get is a Q meter. This is perfect for setting up coils and experimenting with windings.

Ed

DaveG0MXD · 18th Feb 2007, 10:02 pm

Hi Ed,

Check your PM. I also found a jpg of the coils elsewhere on this site!!! All I need to do now is doctor it a bit so I can estimate the winding spacings / etc.

Regards,

Dave G0MXD

16th Feb 2007, 8:39 pm	#1
DaveG0MXD Retired Dormant Member Join Date: Jun 2006 Location: Whitchurch, Shropshire Posts: 8	Codar CR45 Coils I recently acquired an old Codar CR45, but with only one of the green plug-in coils (covers range 3, 160 and 80m bands). Does anyone have information on the winding requirements for the other 4 coils. I have formulated a way of manufacturing coil formers of the correct size and shape, so a set of close-up jpg's of someone elses coils would probably be OK for the two HF bands coils. I had one of these in the late sixties, and would love to get this one back working on all bands again. Regards, Dave G0MXD

17th Feb 2007, 7:44 pm	#2
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Codar CR45 Coils Hi Dave, I have a Codar multi band 6; this appears to use a Denco B9A plug in coil from the green range. I suppose this could be a valve coil in my set as opposed to a transistor one as the multi-band 6 has a Mosfet input which is a high impedance like a valve. These coils sometimes come up on e-bay, or you could see if anyone on the forum has one to spare. It may be possible to experimnet and wind your own, but Denco coils are very compact and efficient. Ed

17th Feb 2007, 8:29 pm	#3
DaveG0MXD Retired Dormant Member Join Date: Jun 2006 Location: Whitchurch, Shropshire Posts: 8	Re: Codar CR45 Coils Thanks Ed, but I omitted to mention that the coils are all octal-based. I believe that the originals were supplied by Denco, as their early coils were octal based, designed for valve circuits. I have collected a lot of information on the size / shape / etc. of the coils, but have so-far been unsuccessful in obtaining winding details. The B9A coils were definitely designed for use on transistor circuits. I also used to own a set of them which I used when I built my first two transistor TRF set from a textbook design published c. 1970. I had also thought of acquiring a set on E-Bay and converting them for use as octal coils (ie: solder an octal plug base onto the 9-pin coil!!). However, this would be a last resort as I am trying for authenticity (and the green coils are etremely rare on E-Bay!). However, if I get the chance I will try and acquire a Multiband 6, to go with my CR45 and CR70A + PR30 (now fully restored). As you may have guessed, I do like Codar gear, ever since I bought my first one!! As a next step, I was considering going back to basics, sticking the coil I have on an RF Bridge, and back-calculating the required inductances and turns ratios from that (and the front panel frequency ranges). Unfortunately, I still would not have any wire size information, but it would be a strart. Unfortunately, it all takes time. Regards, Dave G0MXD

17th Feb 2007, 10:16 pm	#4
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Codar CR45 Coils Hi Dave, the B9A types were available as both valve and transistor types and superseded the octalsa which I think were only valve types. If you PM me your address I'll send a p copy of the Denco data I have. This does not appear to have inductance data as the Wearite coils do but it gives the range with a specific cap swing, so this can easily be calculated. Langford -Smith has all the details of how to make coils. For the lower frequencies something like 35 to 40SWG should suffice and it is not totally necessary to wave wind. Above about 3 MHz it would be better to use a Litz wire, say 7/48 SWG and to wave wind. Try and use a similar spacing as Denco did between the coils to get the same coupling. The best piece of kit to get is a Q meter. This is perfect for setting up coils and experimenting with windings. Ed

18th Feb 2007, 10:02 pm	#5
DaveG0MXD Retired Dormant Member Join Date: Jun 2006 Location: Whitchurch, Shropshire Posts: 8	Re: Codar CR45 Coils Hi Ed, Check your PM. I also found a jpg of the coils elsewhere on this site!!! All I need to do now is doctor it a bit so I can estimate the winding spacings / etc. Regards, Dave G0MXD