CR-70A receiver Checkout

[Grasut8]

Hello,

I’m sure everyone will be quite excited to see my latest acquisition – a 60 year old Codar CR-70A receiver .. (pictured below)

When it arrived in it’s box, I was pleased to see it was in very good condition. With the cover off, it was clean with only light covering of dust. Easily brushed off with a paintbrush.

It has a shiny aluminium chassis with no sign of any modifications.

The mains plug and lead needed a bit of attention. The fuse rating was changed from 13 A to 3 A, and the connections (a bit loose and ragged) were re-fitted.

About a foot of green earth lead was removed from underneath the chassis. It had been wired from the mains entry point, all the way across the radio to the aerial / earth connectors. I used an empty hole in the chassis to fit a 3 mm earthing bolt with solder tag, and reconnected the earth lead to it – much neater.

The valves were carefully wiped, so as not to disturb the valve lettering. They appeared to be original GDR manufacture. The pin alignment was checked with my B9A setting tool.

All seemed to be in good order – no sign of over-heating anywhere.

The original knobs were removed along with the front panel. A bit of a careful cleaning, and everything replaced – except the main tuning knob as you can see, is now an Eddystone knob – sturdy and nice to handle.

The other knobs were replaced by FT101 knobs which are larger and easier to handle.

The mode selection knob is now a pointer style – looks better I think.

With everything replaced, the tuning was checked to move smoothly across the scale. I took the opportunity to diagram the tuning stringing pattern – just in case the string snaps. There's no detail of how to restring the tuning in any user guide I’ve been able to find.

Aerial connected, speaker connected. Time to switch on … phew – lights – music. Everything actually works.

Feed in test signals from my signal generator at various frequencies on each band. All near enough spot on.

Set tuning to low end of 14 Mc/s band – mode switch to CW / SSB – presto, nice Morse code signals.

I don’t think it gets much better than that. Absolutely on tune after all these years.

OK, the construction and components are not top quality, but they are still working.

I know opinion some years back on this Forum was less than enthusiastic, but I think to get such a fun to use and nice sounding radio from just 4 valves is quite an achievement.

The company Codar Radio seems to have disappeared without trace, and with no applause. So I’d like to give them a round of applause for innovative design and performance. Just look at the dual rate tuning, and the simple coil pack design.

Imagine how a simple 4 valve superhet receiver, built to modern standards would sound – I would suggest the analogue sound from a good speaker would be quite seductive. A good basis for a project I think ..

Anyway, I love it ..

Best wishes,

Graham G4EVW

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[Radio1950]

Great story.
Well written.
Even a photo.
Thanks for sharing.

[G6Tanuki]

As a kid I lusted after a CR70A - but funds were limited and so I bought an ex-military TCS12 from GWM Radio in Worthing and built my own power-supply.

A few years later I got to play with a CR70A - and was glad I didn't spend my pocket-money on a new one. The tuning-dial was many tens of KHz 'off' even on 7MHz, it drifted horribly when warming-up [so switch on an hour before you needed to use it] and receiving SSB stations was never really much fun. I viewed it as an 'upstart broadcast-receiver with a BFO' rather than a proper communications-receiver.

I wonder what became of Codar Radio Company? They're not listed on Grace's Guide, nor do they appear in the Companies House records of businesses extant-or-dissolved, which implies that they stopped trading well before the 1990s.

[Restoration73]

This economy receiver was introduced in 1966 at around £20. If images or low gain are a problem you could buy the PR30 preselector.
The advert lists G3SZM,G3IRE,G8BBI as the design staff.
Eddystone S840C was about £66 then.
Codar also made model railway controllers !

[Reelman]

Anyone know what the differences are between the 2 marks? Mine has a more conventional “S” meter so is probably a MK1?.

Thanks,

Peter

[Grasut8]

Hi,

Radio 1950: Glad you liked it.

G6Tanuki: I agree this is not a receiver for amateur comms. For one thing, most amateur bands are only a quarter of an inch long on the scale - so tuning a station is very precise. The markers for each amateur band are only a guide.

You need to have the IF gain turned well down, the aerial trimmer carefully adjusted for max signal strength, and a fairy-like touch on the main dial. With care, single sideband signals can be resolved. Morse is much easier. Very sensitive and low background noise.

I didn't find much drift after 10 minutes from switch on. Remarkable really, considering there is no precision VFO with carefully selected temperature compensatiing capacitors in this radio.

It's intended for general coverage. 0.5 to 30 Mc/s of fun listening is quite an achievement.

Restoration73:

Thanks for the info - very interesting.

Reelman:

The Mark 1 had the valves mounted on the chassis, and used a full wave valve rectifier. The Mark 2 has valves and components mounted on a pcb, an oblong S meter and a half wave silicon rectifier. I think I would have preferred a Mark 1.

All the best,

Graham

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[ORAWA01]

I have a CR70A MK2, and it is one of my favourite radio. The things I like about it is that, it is very lively, sensitive and dynamic in reception. It works well on all the modes AM, CW and SSB reception too. It is also simpler design with 4 valves and not many parts. So if / when problems develop, then it would be easier to work on it than some other big radios with lots and lots of parts and more complicated design.

It is a keeper

[dave walsh]

I had one of these in the mid seventies. It belonged to a young lad whose mother told me had "gone off" his radio hobby as I wrote out a cheque for £13!
That looked new as well. Yes Codar Products, they were very interesting and [like Sinclair stuff] something you would read about a bit enviously but [for what they were] seemed very expensive in the mid sixties. Ten years later I could easily afford the secondhand one but it would have been out of the question for me a decade earlier. I think the IF injection re the BFO was via a "capacitor" [ie a twisted wire]. [Although I could be thinking of another set from a multi branded [Lafayette?] range of basic 5 valve sets that looked very much like proper communications receivers but weren't really]. At least with the Codar range there was no gloss and what you see is what you get! I've a Codar 66 in the north [twin dials] but that's definitely in a poor state. There was discussion and some criticism on the Forum some time ago Graham, as you say but it may relate to the relative cost as much as the technical spec which you have shown to be quite reasonable. What happened to the Company is a bit of a mystery but perhaps they were priced out in the end ? I did some research myself and traced them to an address here on the south coast-Havant I think but there's little else available

Dave

[Ian - G4JQT]

I also had one briefly, but was quite disappointed. Not sure if it was a MkI or MkII. But I felt it was just a MW/SW domestic set with a BFO and IF gain control!

Well built and certainly looked the part, and for the price I don't think there was much else around at the time.

[ORAWA01]

Maybe not one of the serious DX receivers, but still a very fun radio which can do the job in most situation.

For serious DXing, good ATU, Preselector and good external antenna helps a lot. I use my CR70A with a 40m length long wire, Heahtkit Q-multiplier and Mizuho SWL tuner.

[Jimbo]

According to the instruction leaflet for my Codar Mini Clipper, The Codar Radio Company hailed from Bank House,Southwick Square, Southwick Sussex. Their headed paper had the call-signs of G3IRE and G3HGQ, but since I had the Mini Clipper as a Christmas gift from my parents in 1966, I would rather expect that these two are 'silent keys' by now. The letter head also listed Codar Radio of Canada in Tweed Ontario. I believe this information has been posted in earlier threads.

I too longed to own a CR70A, but it was way beyond the scope of a 12 year old schoolboy's pocket money, - it took a fair bit of saving to afford the bandspread tuning capacitor and the audio amplifier that were both optional extras for the basic Mini Clipper!

I built the radio on the dining room table with my Dad's 15 watt 'Remploy' soldering iron and had hours of fun with it, -the beginning of a lifetime's interest in radio and electronics.

I think it was the cost of the 69 volt batteries that caused the Mini Clipper to be put in a cupboard for more than 40 years until I discovered this Forum and built the excellent 'Power Supply for Battery Valve Radios' on the '.com' partner of the '.net' site.

All good fun.

[dave walsh]

Ah yes Southwick Jimbo not Havant but in the same general direction from here in Bexhill! I remember the reference to a Square in the address. Didn't know about the attempt to maybe set up in Canada. That's sort of following in the footsteps of Frank Murphy who died there in the end.

Dave

[Restoration73]

By December 1975, it is £48.75 including VAT, and *Made to Order* "this fine receiver is
not a mass produced item but each set is hand built to your order, individually checked
and air tested". It does not appear in 1976 advert, so a 10 year run - not bad.

The nearest comparable set from the far east would have been the Lafayette HA63A and
this brand became popular in the '60s and 70's , i.e. made by Kenwood.

[ORAWA01]

I was listening the bands with my CR-70A mk2 over the weekend, and it worked very nicely. It works best when the IF control is rolled right back, and the volume control set to maximum, and adjust the sensitivity with the IF control, and volume on the external speaker depending on the signals coming in from the antenna.

The reception is very clean, dynamic and sensitive. The only thing I wish it had is a BAND SPREAD control for the ham bands.

[ORAWA01]

I picked up another CR-70A, this time MK1 thinking it would be a great radio just like my CR-70A MK2.
Well, I was wrong. This MK1 is a dud. It is not sensitive at all on all the bands, and there is no oscillation when switched to CW/SSB. The S-Meter is non functional.
It works OK on MW for the main BC stations, and on SW for the strong AM signals, but that's it. It is needing some checking up for the parts to be replaced, and alignment?

I can understand why some people might have felt this is not good receiver. But I know that my MK2 is a great super receiver.