|
Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
|
Thread Tools |
11th Jan 2009, 2:58 pm | #1 |
Octode
Join Date: Aug 2006
Location: Willington, County Durham, UK.
Posts: 1,499
|
National Panasonic transistor radio unknown model
Hi, can anyone please tell me the model of this old National Panasonic radio. It has MW and 3 short wave bands. Someone has replaced the audio output transistors with an AD161/162 pair and have mounted them (glued!!) on the underside of the cabinet top. Rather a neat job they have done. The radio works but the sound goes low and distorted when the volume is increased.
I need a circuit diagram to figure out what the proper output transistors are. Cheers, Malc.
__________________
Malc Scott |
11th Jan 2009, 3:19 pm | #2 |
Dekatron
Join Date: Nov 2003
Location: Fakenham, Norfolk, UK.
Posts: 4,256
|
Re: National Panasonic transistor radio unknown model
Hi Malc,
I've one just like it, and there's an inner back cover identifying the model as R-441LB. Regards, Paul Last edited by Paul_RK; 11th Jan 2009 at 3:43 pm. |
11th Jan 2009, 3:33 pm | #3 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,846
|
Re: National Panasonic transistor radio unknown model
Apparently covered in the 71/2 volume of R&TVS. And scanned for Paul's discs
|
11th Jan 2009, 3:42 pm | #4 |
Dekatron
Join Date: Nov 2003
Location: Fakenham, Norfolk, UK.
Posts: 4,256
|
Re: National Panasonic transistor radio unknown model
So it is Listed as R-441B under National (rather than National Panasonic) from the service here: the R-441LB is the same except for band coverage and is included in the data. The original output transistors are two 2SB178.
Regards, Paul Last edited by Paul_RK; 11th Jan 2009 at 3:57 pm. |
11th Jan 2009, 4:45 pm | #5 |
Octode
Join Date: Aug 2006
Location: Willington, County Durham, UK.
Posts: 1,499
|
Re: National Panasonic transistor radio unknown model
Hi, thanks to Paul and Nick for their help. I have found the circuit in my R&tvs book. The sound has a good right to be distorted as the output transistors which are fitted are NPN/PNP pair. The circuit shows them as both being PNP. I will try a couple of AC128 in. I looked 2sb178 on the net and one joker advertising them wants £4.95p each!!
__________________
Malc Scott |
11th Jan 2009, 4:54 pm | #6 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,947
|
Re: National Panasonic transistor radio unknown model
My Towers Update 4 gives the AC128 as an equivalent. You might even get some medium power silicons to work if you adjust the bias.
Paul |