I am in the process of recapping one of my receivers that uses many 0.05 MFD
paper caps. Since 0.05s are not READILY available, I am split equally on the
following:

1. Do I recap using the more readily available 0.047
MFD caps even though they are of less capacity
than the original? OR...

2. Do I recap by paralleling readily available
0.022 and 0.033 for a total capacity of
0.055 MFD?

If I do the 0.047 replacement I am violating the
rule I have had beaten in to me about NEVER allow a capacitor to be of LESS
capacity...but when they are
higher it is OK. However 0.047 MF is only 0.003 MFD
off the target 0.05 MFD value whereas the "safer" higher parallel
combination (0.055 MFD) is 0.005 MFD higher than the target capacity.

Thoughts? My receiver uses a lot of the 0.05s so it is not like I only
have one or two to consider.

Thanks for any help.

Gary

"SX-88" wrote in message
...
I am in the process of recapping one of my receivers that uses many 0.05
MFD
paper caps. Since 0.05s are not READILY available, I am split equally on
the
following:

1. Do I recap using the more readily available 0.047
MFD caps even though they are of less capacity
than the original? OR...

2. Do I recap by paralleling readily available
0.022 and 0.033 for a total capacity of
0.055 MFD?

If I do the 0.047 replacement I am violating the
rule I have had beaten in to me about NEVER allow a capacitor to be of
LESS
capacity...but when they are
higher it is OK. However 0.047 MF is only 0.003 MFD
off the target 0.05 MFD value whereas the "safer" higher parallel
combination (0.055 MFD) is 0.005 MFD higher than the target capacity.

Thoughts? My receiver uses a lot of the 0.05s so it is not like I
only
have one or two to consider.

Thanks for any help.

Gary

Gary,
Personal opinion here... I wouldn't hesitate for a heartbeat
to put in the .047s. They're well within the manufacturer's margin
of error in any case. And single .047s are much cheaper and
better looking than a bunch of paralleled caps.
Also... personal opinion as well, I've intentionally used much
smaller caps than OEM in some circuit locations, such as line
bypasses.
Cheers,
Nelson

SX-88 wrote:
I am in the process of recapping one of my receivers that uses many 0.05 MFD
paper caps. Since 0.05s are not READILY available, I am split equally on the
following:

1. Do I recap using the more readily available 0.047
MFD caps even though they are of less capacity
than the original? OR...



I agree... There is absolutely no reason not to use .047's.
de K3HVG

I third the motion. You can actually calculate the needed capacity in any
particular circuit, whether it be bypassing or coupling. The chance that
any particular .05ufd capacitor originally used by the reeceiver
manufacturer would be the calculated value is about as as slim as finding a
nice SX-88 at a landfill. Ballpark is close enough, unless it is in a tuned
circuit.

And, the capacitors usually have a tolerance far greater than the .03 ufd
difference.

Use the .047 and do not give it another thought.

73, Colin K7FM

"SX-88" wrote in message
...
I am in the process of recapping one of my receivers that uses many 0.05
MFD
paper caps. Since 0.05s are not READILY available, I am split equally on
the
following:

Thanks for any help.

Gary


3000 pF isn't going to make much difference in a .05 mFd bypass. You can get
the .05
values from NTE if you feel the need to keep it original. JustRadios.com
probably
has them too. Personally, I'd use the best quality axial lead yellow
jackets I could find.
If you really want to keep it original, consider
restuffing the old cardboard shells from the wax caps to preserve the under
chassis
appearance.

Pete

COLIN LAMB wrote:
I third the motion. You can actually calculate the needed capacity in any
particular circuit, whether it be bypassing or coupling. The chance that
any particular .05ufd capacitor originally used by the reeceiver
manufacturer would be the calculated value is about as as slim as finding a
nice SX-88 at a landfill. Ballpark is close enough, unless it is in a tuned
circuit.

Note that some of these WILL be in tuned circuits, and you'll almost certainly
need to realign the receiver with a sweep generator afterward. But that is
not a bad thing.

And, the capacitors usually have a tolerance far greater than the .03 ufd
difference.

Yes, figure 20% tolerances on those things.

Use the .047 and do not give it another thought.

If you really worry, you can get .05 uF orange drops.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Oct 16, 11:41 am, "SX-88" wrote:
I am in the process of recapping one of my receivers that uses many 0.05 MFD
paper caps. Since 0.05s are not READILY available, I am split equally on the
following:

1. Do I recap using the more readily available 0.047
MFD caps even though they are of less capacity
than the original? OR...

2. Do I recap by paralleling readily available
0.022 and 0.033 for a total capacity of
0.055 MFD?

If I do the 0.047 replacement I am violating the
rule I have had beaten in to me about NEVER allow a capacitor to be of LESS
capacity...but when they are
higher it is OK. However 0.047 MF is only 0.003 MFD
off the target 0.05 MFD value whereas the "safer" higher parallel
combination (0.055 MFD) is 0.005 MFD higher than the target capacity.

Thoughts? My receiver uses a lot of the 0.05s so it is not like I only
have one or two to consider.

Thanks for any help.

Gary


One more thought Gary,
You can look at the application and determine what the purpose of the
capacitor is, the approximate frequency, and the Xc of the capacitor
at that frequency. For instance, it it is in the IF amplifier stage,
you know that the frequency is 455KHz, and can calculate Xc. From
that, you can determine what range of values makes sense to replace
into the radio.
That said, remember that those paper capacitors had values given at
+/-20% tolerance. So why do you have a rule beat into you that you
never replace a capacitor with a value less than the original?
I just re-capped a Hallicrafters S-53A. The paper capacitors are ALL
rated at 600V. However, many of them are in low voltage applications,
and never see more that 30 volts accross them. Why put in a HUGE paper
capacitor? Because it was cheaper for the company to stock just one
part type and use it wherever a .01uF capacitor was needed.
So it is OK to question why a given component is where it is, and make
a judgement call on what would be a good replacement.
Also, as I replace the paper capacitors, I like to wear gloves. The
wax is kind of nasty to get on you.
Have fun, and good luck,
Gary

about as as slim as finding a nice SX-88 at a landfill.

Hey, whaddya mean?!?

http://www.antiqueradio.org/dumpster.htm

:-)

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/html

P.S. I agree with other responders that the .047 is a fine replacement.
Since the old caps were manufactured to such a wide tolerance, your modern
replacements may be closer to the specified value than most of the
originals!

And, Phil's website is as good and concise as it gets about replacing
capacitors. See http://antiqueradio.org/recap.htm

Even if you have been doing it for years, you will appreciate Phil's nice
writing style and useful information.

And, a big fat A for taking the time to help spread his wisdom, learned from
years of experience.

Even after years of repairing radios, we learn that we can do it better. A
few years ago I was going to replace a paper cap in a 17 tube receiver. I
do them one at a time. I clipped the old one out, got a phone call and
dinner call and shut the soldering iron off and left. I was not able to
return to the work for about a month. By then, I knew there was a capacitor
out - but I had clipped the old leads off and it took me an hour of tracing
and schematic reading before I could determine where the missing capacitor
was. Now, I am more methodical and make notes before I clip the capacitor.
A notebook and pencil are always nearby to document before I start work.
Life has been much simpler since then. And, it really is a good idea to
test the radio after a maximum number of changes.

Colin K7FM

"COLIN LAMB" wrote in message
...
And, Phil's website is as good and concise as it gets about replacing
capacitors. See http://antiqueradio.org/recap.htm
was. Now, I am more methodical and make notes before I clip the
capacitor. A notebook and pencil are always nearby to document before I
start work. Life has been much simpler since then. And, it really is a
good idea to test the radio after a maximum number of changes.

Colin K7FM


Keep a cheap set of imported clip leads handy. Place a set over the snipped
leads to "remind" where the old part was snipped from.

Digital photos of sections of the under chassis are also great visual
reminders.

Pete k1zjh