On Sun, 21 Oct 2018 14:08:57 -0400, Ralph Mowery wrote:

In article , says...

A decade ago I'd have recommended doing that, but I don't think you can
buy Sprague Orange Drops anymore. They were the standard replacement
types for those applications for many many years. Now, I guess I would
suggest the Panasonic sputtered mylars from digi-key, or the xicon
sputtered mylars.




I was trying to use the "Orange Drops" as generic term. I probably have
some in the storage bin. Not sure if they are the Sprague or another
brand, but they are orange. Also many others that are similar in
construction and not the ceramic disk type.

I don't use ceramic caps in audio applications but I'm not sure I'd hear
the difference. It's just a matter of "good practice" for me. The old
Philco didn't sound perfect but it didn't sound really bad either. It
was 40 years old at the time and the fact that it then worked pretty well
was good enough for everyone involved.

I think any plastic film cap that has a suitable capacitance and meets or
exceeds the original's voltage rating would be fine. I have some old
paper caps but I'll never use them. Maybe I'll give them to some guitar
amp guy.


I have been working and collecting electronic parts for over 50 years so
have a fair stock for someone that is just in for the hobby and does not
work on them for a living. I just have never gotten into using other
than similar parts for replacment other than electrolytics for the old
oil filled capacitors and tublar ones for the old paper type. I can
work with the older tube equipment, but have not done very much of it as
transistors were in use by the time I really got into electronics. I
just started a Boat Anchor station back in July when I picked up a
Johnson Viking transmitter for $ 40. Now I have about $ 400 invested in
the AM station. It is from about the time I was born.

Sort of thinking about putting together a setup from aroung 1970 or so
using tube equipment. That would have been around the time I got my ham
license. Just out of room now in the ham shack.

In article , says...

I think any plastic film cap that has a suitable capacitance and meets or
exceeds the original's voltage rating would be fine. I have some old
paper caps but I'll never use them. Maybe I'll give them to some guitar
amp guy.



You may want to list the old ones on ebay. Those audio people often pay
big bucks for some of the older types such as those black ones with the
stripes. Think they call them bumble bee caps.

On Mon, 22 Oct 2018 10:37:14 -0400, Ralph Mowery wrote:

In article , says...

I think any plastic film cap that has a suitable capacitance and meets
or exceeds the original's voltage rating would be fine. I have some
old paper caps but I'll never use them. Maybe I'll give them to some
guitar amp guy.



You may want to list the old ones on ebay. Those audio people often pay
big bucks for some of the older types such as those black ones with the
stripes. Think they call them bumble bee caps.

I've saved a few over the years but I've been reluctant to sell my
useless junk on ebay. I mean, it's fine if some eccentric wants to spend
a ridiculous amount of money on junk but I'd rather not deal with some
K00K who feels ripped off and screams to ebay "YOUR JUNK IS GARBAGE!! I'M
FILING A COMPLAINT!!!!!!!!!!!"

I recently bought a couple of Nationals, a NC-60 and a NC-109 from a
guitar amp guy who didn't have the time or inclination to fix them up.
Maybe he will be interested in some sort of exchange of useless junk.

I have the NC-60 open right now and, for what it's worth, National used a
paper cap to couple the 1st audio amp to the power amp. They used a disk
ceramic from the wiper of the volume control to the 1st audio.

In article , Frank wrote:

I have the NC-60 open right now and, for what it's worth, National used a
paper cap to couple the 1st audio amp to the power amp. They used a disk
ceramic from the wiper of the volume control to the 1st audio.

The power amp stage has considerable grid capacitance, so the input impedance
is fairly high, and so a larger value cap is needed. The first audio stage
doesn't have so much capacitance, so you can get away with a smaller valued
cap. And the name of the game is to keep costs down.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Wed, 24 Oct 2018 08:59:28 -0400, Scott Dorsey wrote:

In article , Frank
wrote:

I have the NC-60 open right now and, for what it's worth, National used
a paper cap to couple the 1st audio amp to the power amp. They used a
disk ceramic from the wiper of the volume control to the 1st audio.

The power amp stage has considerable grid capacitance, so the input
impedance is fairly high, and so a larger value cap is needed. The
first audio stage doesn't have so much capacitance, so you can get away
with a smaller valued cap. And the name of the game is to keep costs
down.
--scott

Both caps are .01 ufd. Maybe they were thinking that the larger voltage
deviation after the first audio stage would make a difference.