Codar Mini Clipper

[dirtyden]

Hi,

I purchased an old built Codar Mini Clipper one valve SW 'set'. Two of the three v/caps were damaged (shorting plates).

I completely rebuilt the set (luckily it came with 2 green Denco coils; the larger 6 pin type.

I have had some success with it although as we would expect performance is not great! I built the 2 transistor amp unit off the schematic off vintage radio .me site but the 'original' plans/details while albeit simple, a bit contradictory to follow.

However after adding this conversion to the set the results were dead. I reverted to the original setup. Anyone got a set of diagrams that are a bit easier/ straightforward to follow?

There were even details of the wiring that is taken off the small conversion tag board that had been blacked out for some reason way back in the past. Perhaps someone had spotted a mistake?

Who knows?

Denis

[David 51]

Hi,

I've got a Codar CR45 TRF 3 valve with all the coils that I bought new when I was 14 years old, Now 61, still works without any restoration, good sensitivity but awful selectivity. It's got a sliding hatch on the top so you can reach in to change the coils.

David

[dirtyden]

Hi David,

Have you got a circuit for the clipper? I've built many small one two three valve sets over the years to 'original' circuits but have found mistakes that were glaringly obvious. The best so far was from an early 60s copy of a 'well known' wireless periodical. Perhaps the mistake was found and amended the following month back then, who knows.

Denis

[David 51]

Hi
Sorry no I havn't, just replied as I had a Codar with the plug in coils as you don't hear much about them, bought mine ready assembled as my Dad wouldn't let me build it.
Best Wishes
David

[Jimbo]

Hello Denis,

The photos and the instructions on the vintage radio .me site are of the Codar Mini-Clipper that I built in 1967, at the age of 11, -my first 'proper' wireless kit. There is no mystery about the blacking out of the text in the wiring instructions, I didn't have much of a junk box at that time so I used different coloured wire to what was noted in the text and inked over the original so that I didn't get confused. If you zoom in on the photos you should be able to spot the differences.

I haven't used the Mini-Clipper for many years, and it's currently in store while we moved house, but the basic set and the amplifier worked well. I do recall that the LT part of the battery used to run down quite quickly [and with the 'Pressal' switch it wasn't always clear if the set had been turned off], so last year I made the little battery eliminator that is elsewhere on this Web-site ready for when I unpack the Mini Clipper again!

It needs a decent long length of wire for an antenna and a good pair of high impedance headphones but I had hours of fun with it.

Regards
Jimbo

[AC/HL]

Just out of interest, a contemporary advertisement

[Herald1360]

Originally Posted by Jimbo

The photos and the instructions on the vintage radio .me site are of the Codar Mini-Clipper

Any chance of a full link- I spent some time fruitlessly looking for this last night.....

TIA

[Dave757]

Hi Herald1360,

I had the same problem as you but I did find it in the end!
On the main page under 'Vintage Radio Equipment' select
'Radio Constructor'. Then down the page to 'Vintage Radio Kits',
then select 'Codar Mini Clipper Receiver'
Hope this works ok for you

Kind regards

Dave G0ELJ

[terrybull]

http://vintageradio.me.uk/kits/codar_miniclip.htm

[Herald1360]

Thanks to both for the directions!

The add on transistor amplifier is a neat bit of economy in its supply arrangement.

The HT supply is odd though. 67.5V was a typical small HT battery voltage, 69V though a possible multiple of 1.5V, isn't. Nowadays of course 72V would be easier to find (8*PP3).

[Valvepower]

Hi Paul,

I've also got a Codar CR45 with all the Denco coils, as David 51 said it has good sensitivity but awful selectivity. I bought this at a BVWS Swapmeet a good few years ago.

I know it’s a bit off topic but the talk about Denco coils and the Radio Constructor Magazine reminds me of the ‘The Discovery’ radio, which uses a grounded grid RF amplifier between the aerial and the reflex/ detector stage. This is in the March 1970 copy of The Radio Constructor magazine.

Regards
Terry.

[Ed_Dinning]

Hi Gents, has anyone got any details of the Codar "multi-band 6" a slightly later transistorised unit, again with Denco coils.

Ed

[julie_m]

Originally Posted by Herald1360

The HT supply is odd though. 67.5V was a typical small HT battery voltage, 69V though a possible multiple of 1.5V, isn't.

Probably because 45 cells (= 3 * 3 * 5) is a nicer number for packing (9 * 5 or 15 * 3 tall, thin cells; or 3 * 3 * stacks of 5, or 3 * 5 * stacks of 3 short, fat ones) than 46 (= 2 * 23)

Originally Posted by Herald1360

Nowadays of course 72V would be easier to find (8*PP3).

Or 63 V ..... D-series battery valves are tolerant of wide variations in HT supply (it's always the DK** which is the killer; it stops oscillating if the HT falls too low. But there isn't one in this simple set).

[dirtyden]

Hi Jimbo

Many thanks for the explanation.

Yes, I have 'modified instructions' in the past myself without a thought for those that come across them decades later!!

Anyway I've just completed the build of the small transistor addition today, a bit fiddly but it's done. I have a supply of the old type transistors. I did enlarge the photos and that did help.
The problem I had at first apart from two v/caps damaged was that the amp mod had been done on two separate boards, each enclosed within cans similar to Denco coil cans but larger.
There were wires going everywhere; that's when I decided to rebuild. I had intended to go out to my workshop tonight to finish it off (MUST clean up my bench sometime!) but it turned very cold so will get back to it tomorrow. I'll post how I get on.

Thanks for interest.

Denis

[dirtyden]

Hi

While on the subject of Denco coils (above) I have a 'cigar box' radio I purchased a few years ago. Trouble it was a bit deaf right across the range until I removed a 33k resistor from the regen pot and it EXPLODED into life!

What's this got to do with Denco coils I hear you ask? I got the range of the other coils required; wire gauge, turns etc from an old PW mag.
Now the following might make a few cringe!
As I had around six of these coils purchased cheaply off the internet I decided to sacrifice two (two coils in the set you see) that were for God knows what and turn up two. I made a small Denco coil winder in about an hour (I can give details to anyone interested). VERY fiddly but I got there. I reckon I'm on to the 40mtr band and can bring in 'hams' that loud I need to put a duster in the speaker to quieten things down. I cant back off the regen any more as I then 'lose' that band. I'm going to fit a volume control when I get time.

Denis

[dirtyden]

Hi again Jimbo

Just a note to say I completed the transistor addition to the clipper; what a difference! The output must have gone from 1meg to 20 megs in computer speak!

I used to feed output through: a small LM386 amp then through BHI unit to kill off some of the nasties. Just need to go direct to BHI unit now. On firing up received SW voice (hams) and CW. I would estimate at 5+10 had to reduce volume on BHI to minimum.

Why so excited? I suppose it still gives us all a kick to build a simple device that WORKS!

Denis

[Jimbo]

Good Afternoon Denis,

I'm pleased for you that the Mini-Clipper is up and running. Perhaps you should write it up as a 'Success Story' on the forum. I had enormous pleasure from building and using it many years ago. A simple present of the kit of parts from my Mum and Dad [together with a copy of the Radio Constructor] was the beginning of a lifetimes interest in radio! Happy listening.

Jimbo