It is currently Wed Dec 13, 2017 5:53 pm

Barker 88 post war version.

 
Posts: 2665
Joined: Sun Sep 01, 2013 6:19 pm
Location: Behind the sofa

Re: Barker 88 post war version.

Post by Cathovisor » Tue Jan 12, 2016 12:10 pm

That is indeed the problem: typical values standing the grid off are 1MΩ and 0.05µF which gives a 3dB point of about 3Hz. And yes, that'll gently flutter on the mod as the eye on my Murphy A40C does!

Magic eye patterns at http://www.magiceyetubes.com/patterns.htm

 
Posts: 2853
Joined: Wed Jul 27, 2011 7:13 pm
Location: Croydon

Re: Barker 88 post war version.

Post by sideband » Wed Jan 13, 2016 11:48 pm

Cathovisor wrote:Langrex currently have 427 6U5G in stock Rich - give 'em a call.


Well I sent them an email via their contact page and got a reply back today....£20. I suppose that's not too bad given their availability. I'm inclined to buy one from them even though it's just a tuning indicator. It will finish it off nicely.

 
Posts: 2665
Joined: Sun Sep 01, 2013 6:19 pm
Location: Behind the sofa

Re: Barker 88 post war version.

Post by Cathovisor » Thu Jan 14, 2016 6:11 am

£20 seems eminently reasonable to me.

 
Posts: 2853
Joined: Wed Jul 27, 2011 7:13 pm
Location: Croydon

Re: Barker 88 post war version.

Post by sideband » Thu Jan 14, 2016 9:47 am

Cathovisor wrote:£20 seems eminently reasonable to me.


I agree. Trouble is I remember when they were 17/6d from Home Radio (Mitcham)....... :aaj

 
Posts: 6972
Joined: Sun Aug 14, 2011 11:02 am
Location: Co. Limerick

Re: Barker 88 post war version.

Post by Michael Watterson » Thu Jan 14, 2016 10:09 am

Though factor in Inflation (esp since 1970s) and £0.75 is maybe £10 anyway?

 
Posts: 3712
Joined: Sun Feb 12, 2012 7:43 pm
Location: North Hykeham, Lincolnshire and Ilford, Essex (but not for much longer ...!)

Re: Barker 88 post war version.

Post by Terrykc » Thu Jan 14, 2016 12:00 pm

17/6 in 1960 - which is a more realistic date, I think - is worth exactly £18 now. This, of course, would have been subject to Purchase Tax but, presumably, the Langrex price excludes VAT?

 
Posts: 329
Joined: Tue May 01, 2012 11:23 am

Re: Barker 88 post war version.

Post by turretslug » Thu Jan 14, 2016 12:30 pm

'Tis such a shame that they're short-lived, I have to admit I tend to simply remove tired ones and live without them, but with a small and carefully-stored stash of "odd" types for interest. Would it be worth having a subtly hidden switch for the ME heater to keep its operating hours down to "show" use?- I'm thinking that this would be preferable to HT switching from the cathode-poisoning possibility point of view.

Some receivers/tuners had various techniques for disabling the ME once a signal was tuned in- sometimes it only worked in a "narrow" selectivity position, other times I think there may have been an "electronic" way round- surely an acknowledgement of short ME useful life?

 
Posts: 4092
Joined: Wed May 02, 2012 3:35 pm
Location: Worksop

Re: Barker 88 post war version.

Post by Refugee » Thu Jan 14, 2016 2:00 pm

I have got an AC resistance bridge with a magic eye and it has a front panel switch to shut the eye down so that the unit can remain warmed up. I am pretty sure it cuts the HT to it.

 
Posts: 2853
Joined: Wed Jul 27, 2011 7:13 pm
Location: Croydon

Re: Barker 88 post war version.

Post by sideband » Thu Jan 14, 2016 2:32 pm

turretslug wrote:'Would it be worth having a subtly hidden switch for the ME heater to keep its operating hours down to "show" use?- I'm thinking that this would be preferable to HT switching from the cathode-poisoning possibility point of view.


Something like that had crossed my mind....not sure yet but there are several possibilities.

New 6U5G just ordered from Langrex via PayPal. Hopefully will be here by the weekend.

Terrykc wrote:17/6 in 1960 - which is a more realistic date, I think - is worth exactly £18 now. This, of course, would have been subject to Purchase Tax but, presumably, the Langrex price excludes VAT?


Probably nearer 1968.

There was another £4.80 for VAT plus £4 postage......

(thinks.....) it would have been cheaper to have gone down to Billingshurst and collected it. Probably less than 50 mile round trip from me.

 
Posts: 3712
Joined: Sun Feb 12, 2012 7:43 pm
Location: North Hykeham, Lincolnshire and Ilford, Essex (but not for much longer ...!)

Re: Barker 88 post war version.

Post by Terrykc » Thu Jan 14, 2016 2:49 pm

turretslug wrote:I'm thinking that this would be preferable to HT switching from the cathode-poisoning possibility point of view.
It should be possible to avoid cathode poisoning by putting a 1M resistor across the switch.

 
Posts: 6972
Joined: Sun Aug 14, 2011 11:02 am
Location: Co. Limerick

Re: Barker 88 post war version.

Post by Michael Watterson » Thu Jan 14, 2016 6:06 pm

Terrykc wrote:17/6 in 1960 - which is a more realistic date, I think - is worth exactly £18 now. This, of course, would have been subject to Purchase Tax but, presumably, the Langrex price excludes VAT?

So £20 is a bargain really!

 
Posts: 2853
Joined: Wed Jul 27, 2011 7:13 pm
Location: Croydon

Re: Barker 88 post war version.

Post by sideband » Thu Jan 14, 2016 10:45 pm

sideband wrote:So jobs left to do, restuff the original smoothing cap, sort out the volume control/switch, sort out the heater connection on the 6V6, check alignment (as far as possible without correct information), clean and refinish the cabinet, reassemble, enjoy!


Volume control and switch duly sorted. The control is pretty well sealed so I had to remove it and then bend up the four tabs holding the switch to the pot. A quick squirt of switch cleaner in the switch itself freed up the toggle and away it went. The pot itself was treated the same way and then reassembled. Its very satisfying to operate the switch and at actually turns the radio on....the volume control is also now working without any crackles so that's two more little jobs done.

 
Posts: 2853
Joined: Wed Jul 27, 2011 7:13 pm
Location: Croydon

Re: Barker 88 post war version.

Post by sideband » Tue Aug 16, 2016 6:23 am

Got back to this after months of doing other jobs etc.

Yesterday a small package arrived from Germany containing a triple 16uF 450/500V capacitor. I know I could have restuffed the original smoother with three 15uF caps but as these multiples are so readily available and reasonably priced from Ask Jan First I decided to fit a brand new component. Now if it had been an older 1930's set or for some other reason original looks were important, I'd have probably gone down the restuffing route.

The new capacitor was chosen for three main reasons, cost, size and working voltage. I consider €13.09 to be a very reasonable price even lumping in the €10 for postage, it fits the original clamp perfectly and the working voltage is exactly the same as the original. The tags accept PCB or hard wiring and finally being black in colour, doesn't look too out-of-place as would bright blue, green or red which seem to be popular modern colours. Finally they are made new in Germany so you get a fresh component.

So last night the new component was fitted (in around 15 minutes) using the original clamp. Everything working well so on to the cabinet next.
Attachments
js640_SAM_0917.jpg
The new capacitor
js640_SAM_0918.jpg
The tags for wiring or PCB mount
js640_SAM_0919.jpg
Fits original clamp
js640_SAM_0920.jpg
Fitted in place and wired.
js640_SAM_0922.jpg
Top chassis appearance
js640_SAM_0923.jpg
Working radio
js640_SAM_0924.jpg
The new 6U5 is nice and bright

 
Posts: 2853
Joined: Wed Jul 27, 2011 7:13 pm
Location: Croydon

Re: Barker 88 post war version.

Post by sideband » Sun Aug 21, 2016 11:12 pm

I refitted the tuning scale, cleaned up the cabinet and put it back together....I need the bench space to have another play with my Ferguson '45' portable TV.

It actually looks quite good after just a polish and general spruce up but at some point, I'll get my brother to work his magic on it. There is a small amount of veneer lifting off the top which I've temporarily fixed down with clear Sellotape. That aside, the cabinet is good and the speaker grille being expanded metal just responded to warm soapy water and an old toothbrush. So another 40's set revived.
Attachments
js640_SAM_0925.jpg
Tuning scale cleaned and refitted.
js640_SAM_0927.jpg
Quite a smart-looking set. The P-P 6V6's are LOUD!

 
Posts: 2513
Joined: Sun Jun 10, 2012 7:23 pm
Location: Basildon

Re: Barker 88 post war version.

Post by crackle » Mon Aug 22, 2016 6:22 am

Excellent work Rich.

Mike

Previous

Return to Radio & Audio



Who is online

Users browsing this forum: Bing [Bot] and 3 guests