DIYbanter - View Single Post - Anyone Familiar with the old AN377 FM Radio IC ?

N_Cook

On 05/09/2014 23:44, wrote:
Interesting. Being that getting parts for these old vintage things is not that easy, I might have to try that resistor trick.

Do you concur that the difference is in the IC ? If not that owuld mean two defective parts, which in low power circuitry like this, is kinda rare. If it is something with the coil, that means someone was listening to distortion and all the suddden it stopped working. The way it sounds right now I owuld have never had it switched to FM to even "wear it out" or whatever.

The print is available the Hifiengine if you'd like to have a look, or I could Dropbox it. There is another coil coming off the tank. The tank has two adjustments, but only two connections. Kinda makes me think adjusting that would affect the gain (output per deviation) but it doesn't seem to be working that way. When I first installed the IC, the tuning meter only deflected to the right, but by diddling I got it to balance out. Adjusting either coree doesn't seem to affect the output amplitude.

One thing of note, which might mean nothing, is the original IC was red inked. I know they don't do that for ****s and giggles. It may have been a custom run for Technics. If they used it in all their recievrs, maybe it is a custom IC with slightly different specs. They love doing that bcause it captivates the parts market. However I hold no hope of getting one from Panasonic at this point. Years ago they didn't even have parts for one of their damn RPTVs that cost two grand.

Know what ? Just because I wrote that, you probably CAN get it from them. I was fairly surprised that you can still get a four gang volume control for a Kenwood KR9400.

But not from Kenwood.

What really gets me is the quality of the front end in these old tuners. The new stuff seems to be junk. This thing is in a basement with absolutely no antenna connected and it is picking up stations. Newer recievers seem to get noting and that is with a wire on the antenna. I bet alot of them actually bat their ratings in sensitivity. Now instead of actually designing the thing they just buy a front end from China for like $3 if that, and address it by I2C.

I got a newer Technics stand alone tuner. This thing has it's own powers supply and even an AC outlet on the back, OF A TUNER. It has a rated sensitivity of 0.9 uV which is I think about half of the rating of this 300, and the 300 gets better reception. Even though distorted, it is getting more stations. this has been the case with several vintage recievers and tuners I've worked on recently.

Thanks for the tip. Now to figure out what value of resistor.

If you do any core twiddiddling, mark and note the "o'clockness" and
depth gauge the depth, beforehand , so you can at least get back to
where you started. A slight heating of the core with an iron tip may get
over any threadlock