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Old 4th Feb 2006, 9:54 pm   #1
Phil G4SPZ
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Question Noisy Bush TR82C.

Having read a post from another enthusiast about one of these sets which was noisy on long wave, I was prompted to write about my own set. The audio stage is noisy - white noise, at a fairly low level, irrespective of the band or the setting of the volume control - but otherwise the set is fine and in daily use.

It reminds me of one of my old home brew audio projects, which hissed like mad until I cured it by wiring several hundred microfarads straight across the PP9 battery. Before I try this, does anyone have any other suggestions? Are the output transistors in the TR82 prone to this problem?

Thanks,
Phil
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Old 4th Feb 2006, 10:22 pm   #2
Ed_Dinning
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Default Re: Another noisy TR82C

Hi Phil, I've had problems with resistor noise like this, it was due to those resisrors that are pcb mounting and appear to have crimped on end caps. They are a cheap part so is all else fails change the R's.

HTH Ed
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Old 4th Feb 2006, 11:20 pm   #3
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Default Re: Another noisy TR82C

Quote:
Originally Posted by G4SPZ
Having read a post from another enthusiast about one of these sets which was noisy on long wave, I was prompted to write about my own set. The audio stage is noisy - white noise, at a fairly low level, irrespective of the band or the setting of the volume control
Hi Phil. These sets use Germanium transistors. Take my word for it...they hiss at low level. Germanium transistors are noisey compared to silicon. Even if you change the transistors for brand new Germaniums it will still hiss. It should not be annoying...in other words you should not hear it above the music or speech even at low volume level. Mine and others I have repaired all hiss to the same degree...thats the way they are.


Rich.
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Old 6th Feb 2006, 12:45 am   #4
Phil G4SPZ
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Thumbs up Re: Another noisy TR82C

Thanks, Ed and Richard. You're right, the authentic germanium hiss is only noticeable at very low listening levels and I therefore propose to leave well alone!

Regards,

Phil
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Old 7th Feb 2006, 9:12 pm   #5
Ian G4HJM
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Default Re: Another noisy TR82C

I had a similar problem on my Dynatron Nomad transistor portable. Replacement of the first AF transistor (with an OC70) cured the hiss completely.

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Old 8th Feb 2006, 12:12 am   #6
Phil G4SPZ
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Default Re: Another noisy TR82C

Thanks for the tip, Ian, I'll bear it in mind for when the back next comes off the TR82C.

The set belonged to my wife's late grandmother and I inherited it and restored it (nothing more than a good clean, really - it was filthy) in the year 2000. It gets no more than a few moments use each day. I'm sure the battery is the same one I fitted in 2000!

Regards and 73,

Phil
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Old 22nd Apr 2006, 10:42 pm   #7
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Default Re: Another noisy TR82C

My wife's early version TR82C has a crackle present at switch on(both bands) but clears a few minutes after switch on. Does the team think this could be resistor noise ?
Actually the whole set could do with an overhaul, it sounds slightly distorted, the volume control crackles when operated and the tone control doesn't.
I don't think the insides have been touched since '59!
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Old 23rd Apr 2006, 10:25 am   #8
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Default Re: Another noisy TR82C

Hello,

I have lots of TR82s and they all hiss at low volume .... part of their charm
I just turn the volume up ....

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Old 23rd Apr 2006, 10:03 pm   #9
Phil G4SPZ
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Post Re: Another noisy TR82C

Quote:
Originally Posted by Tim
My wife's early version TR82C has a crackle present at switch on(both bands) but clears a few minutes after switch on. Does the team think this could be resistor noise ?
Actually the whole set could do with an overhaul, it sounds slightly distorted, the volume control crackles when operated and the tone control doesn't.
I don't think the insides have been touched since '59!
Tim, as the crackle is present when adjusting the volume control, the pot itself could be passing DC. Check C29 and C30, particularly C29 which is an 8uF electrolytic and could be leaky.

For distortion, just check whether the distortion disappears when tuned to a weak station. A friend of mine had one of these sets which sounded fine on weak stations but distorted badly on Radio 4 or anything strong. I found that the AGC smoothing capacitor C23 (another 8uF electrolytic) was leaky, shorting out the AGC and causing overloading.

For the tone control, check the control itself plus C35 which could be open circuit. Advancing the control should 'muffle' the audio quite dramatically.

Phil
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