Thanks for your help!
- Greg
: Thanks for your help!
: - Greg
The difference between the Orange Drops and the less expensive capacitors is in their construction. The orange drops are film/foil types and the others are metalized film. The metalized film types will work fine in an old radio. It's just when you start with the audiophile arguments about capacitor's "sound" that the film/foil types become desirable.
Most of the time, you're safe to leave ceramic disc capacitors in the radio. They're pretty reliable. As far as resistors, I prefer the metal film type as they are the most stable and generate the least amount of noise of the three types. Carbon composition types are expensive, and carbon film resistors are noisy. Carbon composition is what was originally
used in the radio. Personally, I don't consider modern components being used in a radio as a detrimental thing. The radio will be performing at its best when bad parts are replaced, and to me, that's the most important.
The best sounding capacitors are an unencased polypropylene film/foil hybrid type or unencased metallized pp.
In most non-critical circuits, paper types "can" be replaced with ceramic disk. I did this in some non-critical circuits of a Hallicrafters SX-42. The only thing with disks is that you watch the voltage range/heat range just as you would any other capacitor. Many times these are most plentiful, and cheap.
Mylar, polyester, etc, can interchange within reason. Working voltage has to be accounted for, and will sometimes rule out one type merely due to it's availability; as well as physical space, and tolerances of the circuit. As well as the usual polarity concerns. Most of the actual differences have to do with the dielectric material of the replacement, and as a result the physical size of the cap. Most Mylars are excellent candidates for slipping inside the old capacitor's cardboard as they are often smaller in diameter and length for a given working voltage and capacitance.
In general, the old mica caps were fairly reliable. The "postage stamp" types too, but don't just assume they are fine if you trace a problem to that specific area of the circuit. I have actually encountered a couple that wound up bad. It does not happen often, but when it does, it can be agravating, because some of those caps can be buried quite well under switches, and wire.
If you are seeking super reliability in someone else's radio that you do not want to see again, changing all of the caps that could dry out is good practice, but on a number of radios that I have, I have a number of the original paper caps that tested well enough, and worked in the circuit. Electrolytics are theonly ones I change automatically if the set shows any kind of noise.
Resistors are another matter. Usually I end up using the older carbon style that I salvage out of old Tv chassis' and radio chassis' that are too far gone. These at least will give the repair an older look to it than using the metal film types. These are also usually the least expensive of the resistors too.
If you are constructing audiophile level equipment, or precise transmitting equipment- Metal film is the only way to go for resistors, and orange drops are the only way to go for capaitors for the "low end" of the spectrum. Resorting only to regular mylar when the voltage requirements get over about 1200 volts.
: Hi all!
: I'm wondering what type of replacement caps are best when replacing wax and paper caps in antique sets? I've heard a lot about Orange Drops, but wouldn't other polyester film caps from Cornell Dubilier or Xicon work just as well? (I ask since these brands tend to be at least half the price of the orange drops.) And, are polystyrene film caps better than polyester film caps?
: Also, should ceramic disc caps be replaced as well? (I know the paper, wax and electrolytic caps should be replaced no matter their value.)
: As for resistors, which type should I use? (I see carbon comp., carbon film and metal film resistors mostly.) Are there advantages of one type over the other (besides tolerance?)
: Thanks for your help!
: - Greg
An added note to the resistors -- Allen-Bradley was the last
U.S. manufacturer to make carbon comp types and they ceased
production about 10 years ago. I don't know that carbon
comp types are being made by anyone overseas. I have a feeling
that any carbon comp types you're going to find will be either
used or new old stock (look for old mom-and-pop TV repair
shops going out of business!).
The biggest advantage to a carbon comp type over a carbon film
type was it's inside bulk. That carbon/clay slug could take
short bursts of power, absorb and dissipate them. A carbon
film resistor has very little resistive bulk and can't take
a power spike without popping like a fuse. Although the average,
continuous power ratings might be the same (e.g., 1/2 watt), a 2-watt
surge for half a second will be shrugged off by the comp type and
will smoke a film resistor.
On the side of carbon film resistors, they do seem to hold a tighter
tolerance. Even new 5% carbon comp resistors might stray 3% or 4%
while a 5% carbon film resistor is usually well-within 1% of its
marked value.
Dean
: Hi, Greg --
: An added note to the resistors -- Allen-Bradley was the last
: U.S. manufacturer to make carbon comp types and they ceased
: production about 10 years ago. I don't know that carbon
: comp types are being made by anyone overseas. I have a feeling
: that any carbon comp types you're going to find will be either
: used or new old stock (look for old mom-and-pop TV repair
: shops going out of business!).
: The biggest advantage to a carbon comp type over a carbon film
: type was it's inside bulk. That carbon/clay slug could take
: short bursts of power, absorb and dissipate them. A carbon
: film resistor has very little resistive bulk and can't take
: a power spike without popping like a fuse. Although the average,
: continuous power ratings might be the same (e.g., 1/2 watt), a 2-watt
: surge for half a second will be shrugged off by the comp type and
: will smoke a film resistor.
: On the side of carbon film resistors, they do seem to hold a tighter
: tolerance. Even new 5% carbon comp resistors might stray 3% or 4%
: while a 5% carbon film resistor is usually well-within 1% of its
: marked value.
: Dean
Ernest
: Hi Dean & Greg, A couple of comments on Carbon film vesus composition resistors. The short term power suge resistance (no pun intended) is something I've never heard of but it's possibly correct, I think it might depend on the individual make of resistor. However the composition resistors have lower inductance than most film resistors, the film is usually cut in a spiral to get a longer effective track length so the resistance track is like a coarse screw thread, a broad carbon wound resistor that acts like a wound choke. The composition are therefore better at high frequency operation. However their construction is similar to a carbon microphone, particles of carbon in a clay binder and they tend to be noisier in low level audio stages. Also they don't seem as stable though this might reflect more modern development in carbon film technology, modern composition resistors may be better than those usually encountered in old equipment. Even new old stock of composition resistors may have drifted in value "on the shelf". Modern film resistors seem to usually be stable over many years. Metal and metal oxide resistors are the best overall and are able to tolerate high voltages better than carbon. Don Black.
: : Hi, Greg --
: : An added note to the resistors -- Allen-Bradley was the last
: : U.S. manufacturer to make carbon comp types and they ceased
: : production about 10 years ago. I don't know that carbon
: : comp types are being made by anyone overseas. I have a feeling
: : that any carbon comp types you're going to find will be either
: : used or new old stock (look for old mom-and-pop TV repair
: : shops going out of business!).
: : The biggest advantage to a carbon comp type over a carbon film
: : type was it's inside bulk. That carbon/clay slug could take
: : short bursts of power, absorb and dissipate them. A carbon
: : film resistor has very little resistive bulk and can't take
: : a power spike without popping like a fuse. Although the average,
: : continuous power ratings might be the same (e.g., 1/2 watt), a 2-watt
: : surge for half a second will be shrugged off by the comp type and
: : will smoke a film resistor.
: : On the side of carbon film resistors, they do seem to hold a tighter
: : tolerance. Even new 5% carbon comp resistors might stray 3% or 4%
: : while a 5% carbon film resistor is usually well-within 1% of its
: : marked value.
: : Dean
I agree 100% with all that's been said about the merits of either type.
Don, I have experimented with both using current surges and the carbon
film types just don't hold up. I've also seen surges that open carbon
film resistors without showing any external damage. That's pretty tough
to do with a composition type.
I also have a lot of NOS composition resistors, and they leave one less
than impressed with their inability to hold tolerance just sitting on the
shelf. You really have to make an ohmmeter check before using them as a
replacement.
I may be repeating myself here, failing to read my past posts, but an
interesting thing did occur with the Tektronix 2213A/2215A scopes that had
a series string of five 510K, 1/2-watt carbon comps in the high voltage
circuits. One by one, the scopes would shift their operating characteristics
until the front panel focus control no longer had enough range to keep the
beam focused. It turned out that in every case, one or more of these 510K
resistors would increase in value, anywhere from 900K to over 20M. I'd never
seen anything like it before, at least to that extent.
: An added note to the resistors -- Allen-Bradley was the last
: U.S. manufacturer to make carbon comp types and they ceased
: production about 10 years ago. I don't know that carbon
: comp types are being made by anyone overseas. I have a feeling
: that any carbon comp types you're going to find will be either
: used or new old stock (look for old mom-and-pop TV repair
: shops going out of business!).
: The biggest advantage to a carbon comp type over a carbon film
: type was it's inside bulk. That carbon/clay slug could take
: short bursts of power, absorb and dissipate them. A carbon
: film resistor has very little resistive bulk and can't take
: a power spike without popping like a fuse. Although the average,
: continuous power ratings might be the same (e.g., 1/2 watt), a 2-watt
: surge for half a second will be shrugged off by the comp type and
: will smoke a film resistor.
: On the side of carbon film resistors, they do seem to hold a tighter
: tolerance. Even new 5% carbon comp resistors might stray 3% or 4%
: while a 5% carbon film resistor is usually well-within 1% of its
: marked value.
: Dean