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Old 22nd Apr 2021, 9:48 pm   #1
ChristianFletcher
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Default Woodsons of Aberdeen SR124

I have a woodsons ships radio the power supply says DF on it so Iím guessing that could stand for direction finding. The set had the following valves EC81 ECH85 EBF80. I have one valve missing which could be related to the IF strip it been suggested as another EF85. The unit is quite tight inside very compact so I havenít really traced the circuit out itís hard to see how the wiring is routed. The unit looks like the SR12 version if anyone could confirm the valve line up or any information. Much appreciated.

Thanks regards Chris
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Old 22nd Apr 2021, 10:08 pm   #2
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Default Re: Woodsons of Aberdeen SR124

Ooh I like that. The receiver itself cannot have any DF facility with just 5 valves total, and wouldn't have met any GPO specification for marine communications, so more like a cabin model for entertainment listening
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Old 22nd Apr 2021, 10:30 pm   #3
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Default Re: Woodsons of Aberdeen SR124

I’m pretty sure these were used as a DF due to the loop antenna signal strength meter and the PIM but admittedly I’m not being smart just read a earlier thread on an SR-12 set. However happy to be proved wrong usually am LOL!

Any info gratefully received

Thanks Julian
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Old 22nd Apr 2021, 10:32 pm   #4
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Default Re: Woodsons of Aberdeen SR124

This may be similar found on a previous SR-12 thread by Johnny. I don’t have the transmitter part as used in radio telephone applications.
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Old 23rd Apr 2021, 5:15 pm   #5
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Default Re: Woodsons of Aberdeen SR124

Sorry, can't offer you any advice. However, that looks really neat! Inside and out.
Wouldn't mind one myself.
Rob
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Old 23rd Apr 2021, 5:42 pm   #6
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Default Re: Woodsons of Aberdeen SR124

It is neat, they look like Denco coils!
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Old 23rd Apr 2021, 6:35 pm   #7
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Default Re: Woodsons of Aberdeen SR124

Fascinating!

It's got a 3-gang tuning-capacitor, which suggests it's got a RF-amplifier stage and so should work rather well on the amateur 160/80-Metre bands.

I also note a bunch of metal-sleeved capacitors with rubber-bungs on their leadouts. These are "sheep in wolves clothing" - inside the shiny metal case is a nasty 'waxy' paper-capacitor which __will__ be horribly leaky after half a century.

If it says Metalpack or Metalmite on the outside, it really needs replacing with extreme urgency!
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Old 24th Apr 2021, 7:23 am   #8
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Default Re: Woodsons of Aberdeen SR124

Two capacitors went on fire as my first attempt to power this up as it was clumsily done by me . It has a separate motor generator so it was all or nothing. I will post some pictures of the power supply people will find interesting
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Old 24th Apr 2021, 9:05 am   #9
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Default Re: Woodsons of Aberdeen SR124

The phrase is, tune for maximum smoke!
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Old 24th Apr 2021, 9:40 am   #10
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Default Re: Woodsons of Aberdeen SR124

Hello Chris,
I used to work for Woodsons back in the early 80's, but by then their own range of marine R/T's were obsolete. They had started to supply Sailor Radio equipment back in the 60's & from the 70's onwards these were their main fitment.
They have a micro-fiche archive of their own produced sets from the late 40's through to the 60's. Woodsons are still very much a going concern & must be the only remaining family run concern in the marine electronics industry. Just look up their website for contact details. All I have is info on their last "Spey" transmitter - the N120.

Regards, David
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Old 24th Apr 2021, 2:30 pm   #11
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Default Re: Woodsons of Aberdeen SR124

I really just need to figure what valve I am missing I’m in the process of tracing out the circuit and fingers crossed it matches the receiver section of the circuit I published previously I think it’s the double triode valve I’m missing but I’m also not sure about the audio output valve. I am working on the radio this afternoon so will post again when I have had a closer look
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Old 24th Apr 2021, 3:43 pm   #12
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Default Re: Woodsons of Aberdeen SR124

I suppose the double-triode is the most likely to have found its way into someone's pocket at some point.... If the 9-pin output valve was an EL84, then a 6CH6 won't harm your wallet as much but it will need a (slight) socket re-wire and change of bias resistor. Good luck, it looks to be an effective radio at heart.
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Old 24th Apr 2021, 4:36 pm   #13
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Default Re: Woodsons of Aberdeen SR124

I have uploaded the datasheet for the valves note the valve numbers are what came in the radio and may or may not be correct ones. I have also published a cut down version of the circuit for the SR-12 the set I have is a SR-124 and it certainly looks very close to the circuit diagram.

So my first question what would be the best replacement for the V8 i think this is a double triode stage. I want to avoid rewiring the base as the unit is very compact and hard to work on so what would be the ideal replacement ? I have quite few valves in stock but I making a point of only stocking what I dont ever actually need for some reason. so a few alternatives would be welcome

I found the reason for the previous smoke in audio output statge 6BW6 that the cathode resistor has gone high from 1k to 4K and the capacitor was near to short cuicuit. I have also repaced the grid coupling cap as it measured 2meg. The 6BW6 is decribed as an RF valve so why is it being used in an audio stage ?

I now get a nice hum when I touch the grid so it is making audio so that progress

finally the drawing of the EBF80 in the valve data looks slightly different to the drawing on the circuit diagram V7 regards the double diod section they come in at an angle on the circuit diagram. Is this a just a differenct drawing for the same thing. I also think the digaram shows D1 D2 pins 7 and 8 swapped around.

Any advice very welcome

regards Chris
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Last edited by ChristianFletcher; 24th Apr 2021 at 4:47 pm.
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Old 24th Apr 2021, 5:10 pm   #14
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Default Re: Woodsons of Aberdeen SR124

Another question what is the correct name for this type of rotary converter. Something not right with this the badge says 24volt dc input. But if used at 24 it puts 12 volts on each filament and nearly 500v Of ht. Running at 12 volts gives me around 6 volt on the heaters and 250 for HT. the label says 250 volt output. No idea why the input voltage is wrong on a factory label

This probably explains why I got the smoke when it was first powered up at 24. That’s what you get for bothering to read the instructions LOL
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Old 24th Apr 2021, 6:28 pm   #15
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Default Re: Woodsons of Aberdeen SR124

6BW6 is good- essentially a 6V6 structure dimensioned to fit in a B9a bottle and a well-regarded device. Not afflicted with price-boosting woo to the same extent as the EL84 either. Quite often, the pigeon-holing of valves was about intended/hoped-for market rather than actual capability and the "audio" valves on miniature glass-button bases with their very short internal connections and low-loss glass base could often operate effectively and efficiently into the low-VHF region. (Though this could also mean that they could mis-behave and do things that weren't intended!).

Perhaps the original 24V dynamotor had been replaced with a 12V type without the label being changed accordingly? Quite a lot of airborne equipment had 24V dynamotors, but with a 12V option available for those cases where 12V electrics were present. Oh, yes- "dynamotor" is the term often used for this type of converter, obviously a portmanteau of dynamo and motor, I think it's originally a US term and may even have been a trade name that became generic. It's a nice touch that you have the converter but they're prone to all the problems of elderly brush motors generally- hardened/dried-up grease, crumbly brushes, tarnished commutators and shorted/open windings!
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Old 24th Apr 2021, 7:47 pm   #16
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Default Re: Woodsons of Aberdeen SR124

Thanks turretslug

Lots of great information Dynamotor sounds right to me. Thanks for information.

Chris
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Old 24th Apr 2021, 8:03 pm   #17
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Default Re: Woodsons of Aberdeen SR124

So far as I can make out, it looks like D102 on the dynamotor (3rd photo, Post#14) if it is then according to this it's a nominal 13.5 volts DC input for 285 volts output:

https://worldradiohistory.com/hd2/ID...rch=%22d102%22

Lawrence.
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Old 24th Apr 2021, 8:36 pm   #18
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Default Re: Woodsons of Aberdeen SR124

Thanks Lawrence that’s brilliant. 13.5V could be right. It’s funny it’s labelled as operating from 24volt I wonder what the story was
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Old 24th Apr 2021, 10:06 pm   #19
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Default Re: Woodsons of Aberdeen SR124

I suspect that radio was designed by the late Doug Gearing GM3ALB. Woodsons Chief engineer, as I remember. I met him a few times in the 1960's - fascinating guy.
He also had two pretty daughters ...
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Old 24th Apr 2021, 10:25 pm   #20
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Default Re: Woodsons of Aberdeen SR124

Is something like an ECC83 or 12AX7 an option for my missing V8. I note the heater arrangement on the circuit diagram implies 12 volt filament. I will put a meter across 4-5 and confirm. I’m not really sure where to start identifying this valve

Thanks
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