Hacker Hunter background noise - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

jjl · 15th Jan 2010, 2:53 pm

Nearly all of the transistors in the RP38A are silicon, this is why these sets tend to be a bit more reliable than earlier Hackers.

The output pair and one other transistor in the audio amplifier are germanium. Germanium output transistors were used as, at that time, medium power silicon transistors suitable for output duty in a portable radio were more expensive and germanium types were good enough for the purpose. I believe that the OC71 is there in part to provide a temperature compensated bias supply for the output pair, a germanium type is used as the output pair are germanium.

Germanium transistors tend to be noisier than silicon due to higher reverse leakage current amongst other things. If there is indeed a germanium sound it would be a hiss!

The RP38A is one of the best sounding Hackers mainly due to the size of its wood cabinet and its speaker. In common with all contemporary Hackers it has an adequately powerful audio amplifier and uses batteries that are capable of providing the required current to the amplifier.

John

Roy London · 17th Jan 2010, 11:57 am

Thanks John

interesting info, thank you, esp the oc71

the Elac speaker is good...I like it...

there is definitely a difference in the tonal quality of a germanium and a silicon transistor....usually perceived as warmth......I've heard it......and so have others...whether it's true of every germanium and silicon comparison is another thing.....

as the Hunter's germaniums are in the output stage of the unit, i would think that they do impart a little to the tonal character of the unit (to some small degree) rather like output valves in a valve amp....

...but whether most people can hear it or not is another matter....

and also I accept that you may correct in that if I switched out the output transistors for silicon perhaps there would be little difference detected......but on the other hand.....

It doesn't really matter what we believe about the relevance of germanium tone at the end of the day.....

it's just a fact that they sound warmer, to some

it's a great little radio.....the Hunter.....great track as well

all the best, .....appreciate your input.....

fiesata · 6th Apr 2010, 10:23 pm

I'm just restoring one of these sets and have got to the point where the noise is in the background as per OP - this thread has saved me a lot of time and effort - many thanks to all posters here.

The sound even with the noise present is superb - well worth the time and effort.

15th Jan 2010, 2:53 pm	#21
jjl Octode Join Date: Jan 2003 Location: Ware, Herts. UK. Posts: 1,082	Re: Hacker Hunter background noise Nearly all of the transistors in the RP38A are silicon, this is why these sets tend to be a bit more reliable than earlier Hackers. The output pair and one other transistor in the audio amplifier are germanium. Germanium output transistors were used as, at that time, medium power silicon transistors suitable for output duty in a portable radio were more expensive and germanium types were good enough for the purpose. I believe that the OC71 is there in part to provide a temperature compensated bias supply for the output pair, a germanium type is used as the output pair are germanium. Germanium transistors tend to be noisier than silicon due to higher reverse leakage current amongst other things. If there is indeed a germanium sound it would be a hiss! The RP38A is one of the best sounding Hackers mainly due to the size of its wood cabinet and its speaker. In common with all contemporary Hackers it has an adequately powerful audio amplifier and uses batteries that are capable of providing the required current to the amplifier. John

17th Jan 2010, 11:57 am	#22
Roy London Retired Dormant Member Join Date: Dec 2009 Location: London Posts: 15	Re: Hacker Hunter background noise Thanks John interesting info, thank you, esp the oc71 the Elac speaker is good...I like it... there is definitely a difference in the tonal quality of a germanium and a silicon transistor....usually perceived as warmth......I've heard it......and so have others...whether it's true of every germanium and silicon comparison is another thing..... as the Hunter's germaniums are in the output stage of the unit, i would think that they do impart a little to the tonal character of the unit (to some small degree) rather like output valves in a valve amp.... ...but whether most people can hear it or not is another matter.... and also I accept that you may correct in that if I switched out the output transistors for silicon perhaps there would be little difference detected......but on the other hand..... It doesn't really matter what we believe about the relevance of germanium tone at the end of the day..... it's just a fact that they sound warmer, to some it's a great little radio.....the Hunter.....great track as well all the best, .....appreciate your input.....

6th Apr 2010, 10:23 pm	#23
fiesata Tetrode Join Date: Jul 2008 Location: Dudley, West midlands, UK. Posts: 74	Re: Hacker Hunter background noise I'm just restoring one of these sets and have got to the point where the noise is in the background as per OP - this thread has saved me a lot of time and effort - many thanks to all posters here. The sound even with the noise present is superb - well worth the time and effort.