klem kedidelhopper wrote:

On Jun 4, 12:57 pm, "Michael A. Terrell"
wrote:
Jeff Liebermann wrote:

On Fri, 3 Jun 2011 17:39:30 -0700 (PDT), klem kedidelhopper
wrote:

I think I've found the transistor that is intermittently failing in my
Grundig 305 transistor radio.

Ummm... could you take a 2nd look at the model number? Grundig makes
the YB-305, but that's not germanium.
http://www.universal-radio.com/catalog/portable/yb305.html
Grundig also makes a 3059, but that's tubes:
http://www.oldradioworld.de/3059.htm

A lot of Grundig radios are almost impossible to locate schematics
for. One radio with his (Transistor) TR-305 model number was for sale
recently on Ebay.

The newest 'TR' series listed in Sams is the TR-17, and date 1965.
There are no YB models listed in Sams, BTW.

It uses four AF126 transistors in the AM/FM IF Amplifier stages. Sams
shows the collector voltages at 0, because each collector goes to ground
through the primary of each pair of IF transformers. A modern meter
will still show some voltage at the collector, but a VTVM used by Sams
would barely make the needle move. The schematic shows between 4 - 6
ohms to ground from each collector.

Perhaps if you disclosed the correct model number, and possibly which
xsistor you're replacing, we can find a schematic, and determine if
your NTE substitute is appropriate?

He said it was AF126, which does cross to ECG/NTE 160.


A lot of good information guys. I'm sorry I didn't include it in this
new post but the radio model is "Transistor 305".It was given to me
around 1970 and it wasn't new then so I'm guessing a bit here. It is
late 60's vintage I think. And I do have a schematic and foil side
board layout too.I did buy two of these 160's. (I wasn't going to open
the second if I didn't have to as they were 5.50 apiece) but maybe
this one is bad. I didn't think I'd have to touch the alignment either
Michael. Just figured that it would work even somewhat.Lenny.


When it isn't working, check the signal at the collector of each IF
amp with your scope. Any shop scope will display an AM IF. If it
disappears at some stage, find out why. If it is missing at the mixer
output, check continuity on the first IF transformer.


--
It's easy to think outside the box, when you have a cutting torch.