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Old 13th Apr 2021, 5:55 pm   #1
stevie23
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Default Codar CR70A Comms receiver.

Hi everyone and hello from London.

I have just won a coms receiver. It is a CR70A and I won it for 16. It was sold as "untested" but appears to be in good cosmetic condition (see picture). Can anyone tell me about this receiver? I'm not a radio expert by any means. I once owned a Hallicrafters SX28A that I LOVED and still have some reels of tape of recordings I made rfom it. I sold it over 20 years ago though. Is the CR70 any good?
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Old 13th Apr 2021, 7:09 pm   #2
Paul_RK
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Default Re: Codar CR70A Comms receiver.

Well, it's not even close to the sophistication of the Super Skyrider, but it was an object of desire for many young short wave listeners back in the day, and for quite a few their first purpose-built communications receiver - or their second, it's a step or two up from an H.A.C.! Do a forum search to find a variety of experiences and opinions, this thread alone brings a few together -

https://www.vintage-radio.net/forum/...d.php?t=168450

Paul
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Old 13th Apr 2021, 7:33 pm   #3
David G4EBT
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Default Re: Codar CR70A Comms receiver.

It's a basic general coverage receiver which was popular in its day, like all Codar equipment. From your picture it looks in pristine condition and you bought it as a bargain price. If it needs any attention, (eg, reservoir/smoothing capacitors and V3 cathode bypass capacitor) it's easy to work on. It has a Beat Frequency Oscillator ('BFO'), so can resolve SSB and CW (Morse) radio amateur transmissions from 160 Metres to 10 Metres (if there are any to be heard these days).

It needs an external aerial to work.

One fault which can result in a dead set is if the OA81 germanium detector diode fails.
If that fault did arise, a IN34A widely and cheaply available if you can't source and OA81 would be a suitable substitute.

You can download the user manual here including the circuit from this link:

http://www.g4kfk.co.uk/Codar_CR-70A_Manual.pdf

Hope that helps a bit and that you get pleasure from owning and using it.
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Old 13th Apr 2021, 10:36 pm   #4
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Default Re: Codar CR70A Comms receiver.

Is it any good?

Well, that depends. They were very good as a beginner's first shortwave receiver. There were cheaper and simpler things around... Paul mentioned the H.A.C. but they had major shortcomings compared to the CR70.

If you've bought it to use it, you'll soon run into its limitations and start yearning for something better in several respects. As you're acclimated the the SX28A this point may arrive fairly quickly.

But for sixteen quid, you've not had to mortgage the house and you can probably sell it foe what you paid and might even get lucky!

So it's costing you nothing for some entertainment and exploration. RA17 next?

David
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Old 14th Apr 2021, 9:08 am   #5
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Default Re: Codar CR70A Comms receiver.

I drove an SX28, nice receiver.

Service Data for the Codar CR70A here if anyone needs a copy:

https://bama.edebris.com/download/co...ice%20Data.pdf

Lawrence.
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Old 14th Apr 2021, 11:17 am   #6
Junk Box Nick
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Default Re: Codar CR70A Comms receiver.

A typical entry level four-valve (plus rectifier valve) general coverage superhet of the day.

A little more sophisticated than its similar four-valve rivals from Japan such as the Unica UNR-30 that was available from GW Smith.

Don’t expect fantastic performance, especially at the higher frequencies (and especially these days where 20, 15 and 10m conditions are appalling compared to the heyday of these sets), and expect some drift. They were reasonable at the lower frequencies and a lot of enjoyment can be had from the set if you accept its limitations.

An external aerial is necessary and using a simple antenna tuning/matching unit will help no end.

Codar had its version of the HAC simple regenerative set called the Clipper, but the CR70A and the T28 were frequently the first ‘proper’ receivers for many young SWLs.
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Old 14th Apr 2021, 12:54 pm   #7
Andrew B
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Default Re: Codar CR70A Comms receiver.

It looks very nice, looking at the manual regarding a voltage output socket. As a first? project you could cobble a pre-selector RF amplifier stage and boost the sensivitity a bit. https://www.opweb.de/english/company..._Company/PR_30
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Old 15th Apr 2021, 10:51 am   #8
stevie23
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Default Re: Codar CR70A Comms receiver.

Quote:
Originally Posted by Radio Wrangler View Post
Is it any good?

As you're acclimated the the SX28A this point may arrive fairly quickly.

But for sixteen quid, you've not had to mortgage the house and you can probably sell it for what you paid and might even get lucky!

So it's costing you nothing for some entertainment and exploration. RA17 next?

David
The Skyrider cost me 15. I also got a National HRO type receiver with 3 modules thrown in for my 15. Mind you that was in 1996...

The Racal RA17? On my budget ? LOL.
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Old 18th Apr 2021, 2:15 pm   #9
stevie23
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Default Re: Codar CR70A Comms receiver.

Hello hello. I picked up the reiceiver yesterday from Chislehurst, In fantastic condition. Smaller than I imagined but thats good. Got it home. It already had a plug on it (no cut cords) so I went for broke and plugged it in. All seems to work. Just a scratchy A.F control which I can easily remedy and I tightened the grub screws on the control knobs so they are nice and secure. Now, I live in Camberwell in S.E London which is fairly built up. I'm at the back of a block with a garden on the first floor. What would be my best antenna option at the preset time? A long wire and a ground to a pipe (or the "third pin? (the largest earth pin) on the mains plug ? THIS IS FROM THE MANUAL!!

Any suggestions appreciated.x
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Old 18th Apr 2021, 6:41 pm   #10
dave walsh
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Default Re: Codar CR70A Comms receiver.

You won't be short of aerial and earth suggestions so I'll stay out of that Stevie. If you put Codar into the search box above there are quite a few hits now! A decade or so back, we were trying to find out the origin and demise of this Company! See "History of the Codar Company" started by Gridleak on 16/11/12. Information on the business and it's products was always thin on the ground. Those relatively simple designs always looked interesting via the ads to pore over in the pages of Practical Wireless. They were not cheap however in the mid-sixties, by comparison with the Radio Surplus market or home construction. If I'd had the money, as a teenager, I would have gone "surplus" for a better set.

Ten years later I bought one second hand for 13. They do look good and work well enough though. I think the general opinion was, interesting products from a short lived Company that started up, did quite well and moved out! Check the other models, they are all quite rare now so anything in good condition is a bonus. There is a Pre-Selector aimed at boosting weak SW signals [the PR-40] but SW Stations are rare themselves these days!

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Old 23rd Apr 2021, 7:53 pm   #11
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Default Re: Codar CR70A Comms receiver.

The CR70A was one of the well-advertised/promoted-to-emerging-SWLs radios back in the 70s - indeed, I lusted after one!

But it was really just a slightly-better-than-average broadcast-receiver with a BFO so it could resolve those newly-fangled hams and their SSB.

OK, it had a 'high-Q' front-end tuned-circuit using an air-spaced coil - but it still suffered horribly with broadcast-band 15MHz image-stations when you were trying to listen to the 14MHz ham-band.... and even on the lower bands the selectivity was not really up to the standards you needed for SSB.

Being general-coverage really was a problem too: when an entire amateur-band occupied 1/3 an inch on the dial and no more than half a turn on the tuning-knob it made resolving SSB a nightmare!

I like to see the CR70/A as a good broadcast-band radio for the budding SWL - and quite good for MW DXers - but as a ham-band radio it was really rather flawed.
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Old 24th Apr 2021, 3:08 am   #12
martyjames
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Default Re: Codar CR70A Comms receiver.

I owned a CR 70A. I was a 14 year old keen SWL living in New Zealand and Codar shipped one out to me! It is/was a great looking receiver and i loved it. Like others said the higher frequency listening was mediocre but overall a great Brtitish made receiver - happy days!
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