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Another KB 151

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Anonymous
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Changed the audio coupling cap and the set worked as soon as the voltage rose enough on the variac. Nothing too exciting to report on this one other than R25 decided to pop after about 15 min of slowly soaking on a slightly reduced voltage. It may have been extra load due to leaky brown hunts. Lesson learned.
Managed to find a 2.5k 5 watt and fitted that. Changed all the brown hunts, they were all 0.005 except 2. Going to have to restock on these now.
There is a crackling at the very high frequency end of the dial, sounds like the tuning cap vanes touching, but cant understand because the vanes are more or less completely not overlapping. I have tried tightening up the spring which rubs on the moving vanes. It is soldered at one end and I just heated it with the soldering iron and held it with a screwdriver and pushed in by about 3mm, crackle is still there. Still it does not really interfere with the stations (much)
Cleaned up the case and I am very pleased with my new purchase, just one or 2 very slight marks on the case. Lots of stations so alignment must be OK.
Mike

 
Posted : 21/11/2012 8:41 pm
Katie Bush
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That looks like a nice little set, Mike.

I seen to remember having a Bush TR-82 with a noisy tuning cap.. If memory serves me, it was the build up of 'Daz' (aluminium oxide) on one half of vanes that was just 'bridging' the gap between the fixed and the moving vanes.. It wasn't much, but it made the cap almost unusable.

Marion

 
Posted : 21/11/2012 10:51 pm
Anonymous
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Yes, but usually it's worse at LF and vanishes at HF. Must be something else.

 
Posted : 21/11/2012 11:30 pm
Anonymous
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All I can think of is some persistant dirt on the spindal where the moving vane wiper rubs.
I cant get to it to clean as the vanes are all "out" at the point it happens.
I cant think what else it can be :ummm?: :'(

 
Posted : 21/11/2012 11:55 pm
Anonymous
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That looks like a nice little set, Mike.
Marion

Yes I am very pleased to have it. I have been after examples these style of KB portables for ages. They seem to go for silly money, I got this one and an OP21/1, a transistor one for what I class as a reasonable cost both within a couple of weeks.
Oh I forgot to mention, this latest one even came with the special plug with long pin which activates the Battery/Mains change over.

My mini museum is coming along.

 
Posted : 22/11/2012 12:09 am
Anonymous
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Looking good. I see you really do specialise in KB-ITT :)

Maybe I should swap you my MP151 for something you don't really collect that I do :D

 
Posted : 22/11/2012 10:09 am
Anonymous
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Thats a good idea, I might take you up on that, shall I send you a list of what I have available.
I could even post the list on the swap/for sale forum in case others have any sets I can swap with.
Mike

 
Posted : 22/11/2012 10:30 am
alanworland
(@alanworland)
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Hi Mike,

Thats a nice looking set you have - good work!
Re 'the crackle' are there any earth braids on the tuning cap and are the intact?

Alan

 
Posted : 22/11/2012 11:49 pm
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