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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 4th Jun 2022, 7:23 pm   #1
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Default Eddystone EC10 MkII

What is the general opinion of these very early transistor comms receivers? It's only single-conversion with Germanium transistors. What is the general performance like?
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Old 4th Jun 2022, 7:39 pm   #2
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Default Re: Eddystone EC10 MkII

Biggest problem with my one was frequency drift, particularly noticeable when receiving SSB or morse. Watch out for tin whiskers with some of the transistors.
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Old 4th Jun 2022, 7:50 pm   #3
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Default Re: Eddystone EC10 MkII

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Originally Posted by Vintage_RC View Post
Biggest problem with my one was frequency drift, particularly noticeable when receiving SSB or morse. Watch out for tin whiskers with some of the transistors.
That's what I thought. There is supposed to be some voltage stabilising in the front-end and of course the OC170's suffer from the same troubles as the AF11x transistors. All fixable though.
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Old 4th Jun 2022, 7:52 pm   #4
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Default Re: Eddystone EC10 MkII

Easily overloaded
Whiskers already mentioned
Doesn't have the selectivity, stability or tuning speed for SSB or CW.

They work, but you have to drive them continuously.
Great looks, but not fun to use.

David
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Old 4th Jun 2022, 7:59 pm   #5
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Default Re: Eddystone EC10 MkII

Glorified domestic receiver, though an Eddystone drive. PS But going up in price, more so the MK1.
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Old 4th Jun 2022, 8:17 pm   #6
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Default Re: Eddystone EC10 MkII

I have one here and it's just about OK for SSB on 80m, anything higher is a waste of time. I nice receiver but tends to go microphonic with the gain flat out.

There are good fun if you can pick one up cheap, but not really worth what they're commanding these days.
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Old 4th Jun 2022, 8:26 pm   #7
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Default Re: Eddystone EC10 MkII

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Glorified domestic receiver,
Hmmm yes I was thinking along those lines. Still it might be worth considering since I don't have anything with a BFO that covers the usual amateur bands. I can always try adding 'extras' to it.
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Old 4th Jun 2022, 10:16 pm   #8
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Default Re: Eddystone EC10 MkII

No, just jump in for an EA12

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Old 5th Jun 2022, 4:31 am   #9
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Default Re: Eddystone EC10 MkII

Back in the late 60`s early 70`s when they were first sold, they were never that popular with the Amature Radio fraturnity, and were then considered poor performers and bit over priced, I think their compact size was the biggest selling point.
I bought a cheap working one about about 20 years ago with a open mind, but even once the whisker problem is resolved and other components replaced, I still think all the criticism is justified.
I just cant believe what their selling for now

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Old 5th Jun 2022, 5:01 am   #10
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Default Re: Eddystone EC10 MkII

Cuteness would seem to be lucrative.

The Eddystone dial/drive isn't all it's cracked uo to be. It has a fundamental flaw. The tuning knob shaft is in a small plain bearing. Once the bearing wears and there is some play, the shaft can waggle in the bearing and cause as much tuning movement as quite a large rotation would. The tuning knob shaft has a small diameter friction drive onto a large diameter shim-steel disc and a little shaft waggle is comparable to a significant fraction of the circumference of the tuning shaft friction drive circumference.

This is in all Eddystone models that I've seen, even the much vaunted EA12 and the 898 component dial.

Criticising the Eddystone dial is shooting a holy cow, but have a look. They don't wear well.

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Old 5th Jun 2022, 8:36 am   #11
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Default Re: Eddystone EC10 MkII

OK thanks. I saw one at a not unreasonable price on eBay and am watching it. I haven't bid yet and judging from the above, I'm unlikely to! I'll be interested in its final selling price though!
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Old 5th Jun 2022, 9:57 am   #12
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Default Re: Eddystone EC10 MkII

EA12 as stated, very well respected and sort after as is 888A
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Old 5th Jun 2022, 11:05 am   #13
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Default Re: Eddystone EC10 MkII

They're generally quite nicely put together, but electronically unexciting. An expensive box with pedestrian innards, I wondered how they stayed in business for so long but possibly the military/professional/marine market for sets like the 730, 830, 880 series and solid-state successors helped sustain the rest of the business.

The EC10 variants and 840 series always seem to be plentiful on the market, so the high prices achieved are somewhat puzzling.
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Old 5th Jun 2022, 11:54 am   #14
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Default Re: Eddystone EC10 MkII

Puzzling to watch from a distance. Just as long as it's not your own money.

Look at the prices of the Eddystone GDO and bug key.

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Old 6th Jun 2022, 6:30 pm   #15
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Default Re: Eddystone EC10 MkII

They're really rather pedestriian: a single-superhet with a low-IF, clockwork local-oscillator, wide-as-a-barn-door IF, and simple diode-detector. OK as a broadcast-listener radio but really not up to modern band-conditions.

Drifty HF local-oscillator, which will inevitably shift hundreds of Hertz with AGC actioin/adjusting the RF gain; loads of image-signals when you're listening to anything above 10MHz, and there's no product--detector to cope with SSB.

I kinda think of them as a backwards-step from the likes of my Eddystone 840A.. where I'm used to using the RF Gain control as a sort of 'clarifier' when listening to 14MHz stations...
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Old 6th Jun 2022, 8:38 pm   #16
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Default Re: Eddystone EC10 MkII

Checking the schematic, the i.f. filtering feeds wideband filters then the last i.f. is a single tank coil, meaning it has less bandwidth than the proceeding stages. In radio design, this is incorrect design, always feed narrow band into wideband.
Also, it has only a single stage rf amp, common base, which means it will be plagued by image frequencies and also the EC10 will have a lack of sensitivity.

The above problems are not attributal to solid state germanium transistors but bad circuit design throughout.The HRO and the Hammarlund sp400x are also only single conversion superhets but both use 3 tuned tanks on their respective front ends making all the difference in regards to image rejection and sensitivity.
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Old 6th Jun 2022, 8:53 pm   #17
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Default Re: Eddystone EC10 MkII

I would have perhaps forgiven the Eddystone designers if they'd incorporated a crystal-filter in the IF, and so made the thing _vaguely_ usable for 'single-signal' CW reception and maybe SSB.

But such narrow IF selectivity would have only highlighted the innate drift in free-running local-oscillators/BFOs without voltage-stabilisation.

A Class-B audio output stage, with its current-draw-fluctuating-with-volume really didn't help matters either; at least the 'classic' valve radios like the HRO and CR100 had Class-A audio stages which didn't vary with volume and also served as a nice base-load on the HT rail so it didn't fluctuate too much.

The Heath 'Mohican'[ is interesting in comarison to the EC10; they both suffered from first-generation-Germanium-transistor problems, a low IF and insufficient signal-frequency selectivity, but the Mohican did at least have a few "Transfilters" [made by Brush-Clevite corporation] to enhance the IF selectivity-curves.
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Old 6th Jun 2022, 9:23 pm   #18
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Default Re: Eddystone EC10 MkII

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Originally Posted by Sideband View Post
OK thanks. I saw one at a not unreasonable price on eBay and am watching it. I haven't bid yet and judging from the above, I'm unlikely to! I'll be interested in its final selling price though!
I've just checked Ebay for Eddystone EC10 MKII and one came up for £200.00 minimum bid, my advice would be add an extra £50 or so and get a Yaesu frg100 or a Lowe HF225 etc.
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Old 8th Jun 2022, 10:22 pm   #19
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Default Re: Eddystone EC10 MkII

I have bought three in the past... all modified, or totally rebuilt..the only thing I can think of as being good is the case.... the rest was good "In its day", as mentioned, very microphonic, drifts a bit.... hopeless on SSB... I rebuilt one just for amateur bands... new RF front end, IF and all the rest. They are fetching ridiculous prices. I shudder when I see the ads over £30..
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Old 9th Jun 2022, 9:19 am   #20
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Default Re: Eddystone EC10 MkII

I bought one about 20 years ago due to a severe attack of nostalgia. In my schooldays the EC10 was the receiver all my 'radio pals' drooled over but I never owned one.
Fast forward to the late 90's/early 2000's and one came up locally so I ended up with it.
What a let down! It worked, but it was clearly a product built down to a price and the circuit looked like a slightly tweaked domestic transistor radio. The tuning rate on the higher bands was ludicrous and the LO drifted.
There was also severe 'pulling' on strong SSB and CW signals and the lack of a proper product detector meant the RF gain had to be kept low leading to rather dull performance. Then there were the images at the high end.
Although it looked nice on the shelf, that's where it stayed.
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