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Old 4th Dec 2005, 1:56 pm   #1
af024
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Unhappy Peculiarities of the KB FB10 'Toaster'.

I have finally managed to get my hands on a KB FB10 'Toaster'. Regettably however the phantom component thief has been in there! I am busy trying to see what's gone but I have two questions ....

(1) Looking at Trader Service Sheet no. 969, C13 is quoted as being 0.1pF. This MUST surely be wrong.

(2) My set has a 6BW6 fitted for V4. The service sheet talks about a 6V6GT (different base of course). Is this someone's botch or is this a recognised factory fit at some point during its production run?

(3) R13 is quoted as being 113R (comprising 150R and 470R in parallel). My set only has 1 x 150R. Again is this normal, or is it likely that the 470R has been pinched by the phantom?

(4) Were the following caps TCC-type waxes ... C1, C8, C9, C13, C15, C18, C19? Does anyone know what the original voltage ratings were please?

Thank you in anticipation of your help.

Regards,


Andy

Last edited by Darren-UK; 10th Jul 2007 at 9:52 pm. Reason: General tidying.
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Old 4th Dec 2005, 2:16 pm   #2
Darren-UK
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Default Re: KB FB10 'Toaster'

Hi Andy,

C13 should be 0.1uf. The rest of what you asked is quite 'normal'; KB were famous for mucking around with circuits in mid-production and hence several variations exist. This includes the resistors-in-parallel thingy, where I think the change came between early and later models IIRC the single resistor was found in later versions but someone may correct me on that.

I can't remember now which caps were TCC's but I do recall they were rated at 350vdc wkg. Don't forget, btw, that these radios used an auto transformer as opposed to a proper one
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Old 4th Dec 2005, 2:21 pm   #3
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Default Re: KB FB10 'Toaster'

Quote:
Originally Posted by af024
(2) My set has a 6BW6 fitted for V4. The service sheet talks about a 6V6GT (different base of course). Is this someone's botch or is this a recognised factory fit at some point during its production run?
A 6BW6 is electrically the same as a 6V6: http://www.r-type.org/exhib/aaa0343.htm

I don't know if this would have been factory fitted, but KB were notorious for making quite major changes during a model's production run.

Best regards, Paul
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Old 4th Dec 2005, 3:44 pm   #4
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Default Re: KB FB10 'Toaster'

Hi Andy,

I restored a KB FB10 recently and have lots of digital pictures of the chassis detail (before and after) from above and below. If you need to undo some of 'the phantom's' work they may be of some help.

Let me know if you'd like them and I can pass them on.

rgds
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Old 4th Dec 2005, 5:13 pm   #5
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Default Re: KB FB10 'Toaster'

Hi Gents as Paul says, KB were notorious for changes. I even had an FB10 with a IF stage missing. There was a space for the valve and IF but not fitted. The performance was as would be expected. It had a very low serial number so this could have been an attempt to see what they could get away with.

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Old 4th Dec 2005, 10:24 pm   #6
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Talking Re: KB FB10 'Toaster'

Thanks one and all - all good stuff.

Thanks too about the reminder of the auto transformer. Goodness knows whay they didn't go the whole hog and do it properly. Saves on copper I suppose. How tight is that?

AND a big, 'Yes please' to the photos stretch289! I'd like to get it as authentic-looking as possible. Your photos would be a great help - my Trader copy is a bit rough.

Many thanks.

Regards,


Andy
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Old 5th Dec 2005, 11:53 am   #7
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Default Re: KB FB10 'Toaster'

Andy,

I've zipped up some FB10 pics for you. If you need any more detail you can have them in an uncompressed format (all 1Mb plus).

Hope they're of some use.

rgds
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Old 5th Dec 2005, 6:59 pm   #8
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Default Re: KB FB10 'Toaster'

I had a quick look at mine today (s/n 123347), and it has a 6BW6, but the chassis looks as if it was made to accept Octals for both the output and the rectifier. There are large slots in each end of the chassis, eah containig a rivetted in plate with a B9A socket riveted to it.


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Old 5th Dec 2005, 7:36 pm   #9
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Default Re: KB FB10 'Toaster'

I happen to have two pics of my own FB10, so am posting them here for the interest of Andy or anyone else for that matter. Obviously, my radio is not restored - just repaired as necessary. I've owned it for many years and it performs well. This example uses a 6X5GT. On the underside view, note the two ancient-looking caps on the righthand side; these are 'Erie' brand and remain in gwo - perhaps unlike Hunts or Radiospares offerings of similar age. Curiously, the volume control is a LIN and not a LOG; very doubtful this is original but I just don't know.
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Old 5th Dec 2005, 8:18 pm   #10
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Default Re: KB FB10 'Toaster'

Well that proves the octal theory then! It looks like the original design used a 6X5GT and a 6V6GT, which where then replaced with B9A equivalents (EZ80 (6X4?) and 6BW6 in mine), and there are a number of sets with combinations of the above.

Has anyone got the version with the two octals in it?

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Old 5th Dec 2005, 10:08 pm   #11
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Thumbs up Re: KB FB10 'Toaster'

Many thanks one and all.

All of this is great stuff - I am much obliged.

Interestingly, the aerial in my FB10 is not on a ferrite rod. It's just a large coil of wire (well two coils actually) wound round the back and supported on what looks like card. It looks like it’s built to cook over the heat from the valves! So, even more variations are coming to light. Regrettably there is no serial number on mine as the paper label is missing.

Interesting stuff eh.

Well, armed with all that useful gen I'm now off to see what I can do.

Best regards all – great help!



Andy
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Old 5th Dec 2005, 11:03 pm   #12
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Default Re: KB FB10 'Toaster'

Quote:
Originally Posted by af024
Interestingly, the aerial in my FB10 is not on a ferrite rod. It's just a large coil of wire (well two coils actually) wound round the back and supported on what looks like card. It looks like it’s built to cook over the heat from the valves! So, even more variations are coming to light. Regrettably there is no serial number on mine as the paper label is missing.
That will be a frame aerial. Ferrite rods were just being introduced around that time - another mid-production design change by KB

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Old 5th Dec 2005, 11:48 pm   #13
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Smile Re: KB FB10 'Toaster'

Looks like they enjoyed tinkering about with their production runs. Or was it a case of, 'What components do we have most of today?'

Amazing - I had no idea that there were so many variants.

Makes it interesting anyway.

Regards,


Andy
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Old 6th Dec 2005, 12:29 am   #14
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Default Re: KB FB10 'Toaster'

Quote:
Originally Posted by af024
Looks like they enjoyed tinkering about with their production runs. Or was it a case of, 'What components do we have most of today?'

Amazing - I had no idea that there were so many variants.

Makes it interesting anyway.
As myself and others have said, KB were notorious for altering things in mid production; some people say this was 'just them' and others have theories about it being a matter of what components were available at the time. In 1950 there were still a few shortages following WW2 and then we had - as only the British can - a few more wars such as Korea and Suez, which also had some bearing on component supplies but to a lesser extent.

Saying all that, the same 'problems' didn't seem to exist for, say, Bush and their DAC90A etc etc. Back to KB again, similar strange variations existed in both the valve and transistor Rhapsody series.

So Andy, having collected all the 'Toasters' with electrical oddities you can then start collecting them in different colours
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Old 6th Dec 2005, 12:56 am   #15
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Default Re: KB FB10 'Toaster'

Hi

I have got 5 of these things, all as found at sales etc.
I have never got around to doing anything much with any of them.

FB10 serial no. 06039. 6V6GT and 6X5GT (see pic)
FB10 serial no. 81812. 6BW6 and 6X5GT
FB10 serial no. . 6BW6 and EZ80 but on an octal adaptor (see pic)
FB15T serial no. 04372. 35L6GT and 35Z4GT M/W S/W AC/DC 110/240V export version
FB15FM serial no. 04372. solid state rec, I assume in place of a selineim rec.

If anyone wants pics of them all, let me know.

Richard.
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Old 6th Dec 2005, 10:34 am   #16
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Default Re: KB FB10 'Toaster'

So it looks like there may be 8 chassis variations of the FB10, before we start to consider other sets in the same case (FB10FM, FB15 etc), and a production run in excess of 120,000 units! (plus the other models).

I suspect that it is more a case of inteligent design than anything else - when the set was introduced (1950), the new B9A valves were just starting to appear, so to design the set to take either would keep your options open, and also allow the set to be easily adapted for other markets. If it was just component shortages, all manufacturers sets would be like this in the late 40s / early 50s.

Pauls service CD's give two versions of the set, and start that the all minature valve version started at sn 110001, so the strange hybrids are probably earlier production.

Jim.
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Old 9th Jan 2006, 10:47 pm   #17
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Angry Re: KB FB10 'Toaster'

Well guys, the saga of the FB10 continues. I was busy installing capacitors to replace those that had been pinched by the phantom only to find some discrepancies between the beast itself and the Trader 969 Service Sheet. Let me explain ....

(1) C13 is down on the sheet as being 0.1pF, ok, we sorted that one – some kind soul told me that it should have read 0.1uF – much more sensible.
(2) C2 on the sheet is down as being 70pF. Fitted in my set was quite definitely a brown Hunts 001, 350V capacitor. Now if you read it literally as 0.001uF, this translated to 1000pF (which is clearly miles higher than 70pF). If one reads it backwards – ie 100 and assumes it to be 100pF then this is close I suppose, but here’s the but, removing it from circuit and measuring it with a Peak LCR reveals 1.8nF (ish) (which is close to 0.001uF). There was no sign of tampering around this component and the soldering was as black as all other untouched areas so what’s going on there I wonder? I have taken a couple of photos of the actual component that I removed.
(3) R2 on the sheet is quoted as being 220. No units are quoted, so we are probably led to believe that it is 220 ohm. Not so. The example in my set (and in the photos that were previously kindly provided) is quite clearly RED, RED, ORANGE which to my mind means 22000 ohm (22k).
(4) R13 is a mystery too.

So really the sheet isn’t that good is it. Can I believe anything it tells me – that’s the question? Does anyone know what the real values are please – particularly C2?

Many thanks one and all,


Andy
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Old 10th Jan 2006, 6:04 am   #18
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Default Re: KB FB10 'Toaster'

Hi Andy,

I've extracted the chassis of my FB10 (114331), but it seems only to add to the confusion

(2) The only .001uF Hunts component (which does look very like the one in your photo, even as regards lead lengths - and yours definitely is a .001uF) is C1, to the aerial socket: C2 in mine is a variable ceramic type, mounted on the chassis flange 'twixt tuning knob and wavechange switch as in the photo of Darren's set.

(3) I've looked at the photos, and can't see R2 clearly on any of them. R1, 22k to an earth tag, is quite conspicuous. R2 in my set is 220 ohms as per the circuit, and resides, on long leads, beside the aerial and oscillator trimmers, with one end connected to the same valve base tag as R1 and the other to the tuning condenser above the chassis.

(4) Opinions as to the best value of the rectifier surge limiter R13 seem to have fluctuated The circuit gives 113 ohms, your set has 150, mine has two 150 ohm resistors in parallel...

Paul
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Old 11th Jan 2006, 7:57 pm   #19
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Angry Re: KB FB10 'Toaster'

Thanks Paul,

Oh dear oh dear, I see what you mean. It's amazing that this radio ever worked. Did people just pick up anything and sling it in there (with fingers crossed) or what? It certainly seems so. How strange.

Well I must say that I'm at a bit of a loss now.

The saga continues.

So just why DID I purchase an FB10 then? - good question!!

A rather frustrated person ... Arrrgghhhhhh!!!
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Old 11th Jan 2006, 9:39 pm   #20
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Default Re: KB FB10 'Toaster'

There were lots of variations to the circuit on this model. Paul is not far off the mark....the manufacturers tended to use what was available so there are variations in valve types and components used. some sets have a mixture of octal and B8A some have B8A and B7G. Others have all B8A or all octal...there are probably some that have octal and B7G. Some have chassis punched for octal but have conversion plates fitted in the original holes to take different size valves....the list goes on.

You will probably have to obtain several circuits from different sources and kind members of this forum to provide more info (I only have the trader sheet).

That said though I still think these are great little sets.


Rich
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