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New owner of HP 410LR VTVM - need probes - where to buy?
Hi,
Just picked up a HP 410LR cheap. It came with no cables/wires besides the AC cord. That is, no probes. I understand to make full use of this instrument I will need some special probes. Where can I get a set? I plan to use it to calibrate my tape machine and to fix tube amplifiers in general. Thanks, Chris |
New owner of HP 410LR VTVM - need probes - where to buy?
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New owner of HP 410LR VTVM - need probes - where to buy?
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New owner of HP 410LR VTVM - need probes - where to buy?
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New owner of HP 410LR VTVM - need probes - where to buy?
On Sep 4, 1:30 am, Chuck Harris wrote:
HP410LR? That's a new one to me. I am aware of the 410A, 410B, and 410C, but not the LR. The 410(A,B,C) have their DC/Ohms probes wired directly to the instrument, and their AC probe has a vacuum tube diode in it, and plugs in by way of a Stereo Phone Plug. Can you describe this instrument for us? -Chuck Sorry, it's a HP 400LR, a rack mount version of the 400L. My unit has binding posts. |
New owner of HP 410LR VTVM - need probes - where to buy?
"Richard Knoppow" wrote in message ... The 400 series meters are AC meters, they do not have DC or resistance ranges. The 400L is the same meter as the 400D and H other than the special meter movment which displays the voltage on a logrithmic scale and has a linear decibel scale uppermost. It does not need any special probes or accessories. Richard is correct. May I add that my HP400H, the model with linear scales, was full of black plastic encapsulated paper capacitors (sometimes called bumblebees or black beauties). These capacitors are well known for their failure rates. There may be a reason you got a good price on your meter. --Chuck N7RHU |
New owner of HP 410LR VTVM - need probes - where to buy?
On Sep 4, 12:03 pm, "Chuck" wrote:
Richard is correct. May I add that my HP400H, the model with linear scales, was full of black plastic encapsulated paper capacitors (sometimes called bumblebees or black beauties). These capacitors are well known for their failure rates. There may be a reason you got a good price on your meter. "Cheap" meaning free is about the best price one can obtain. Shouldn't be hard to replace the caps, right? Am I missing something here? |
New owner of HP 410LR VTVM - need probes - where to buy?
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New owner of HP 410LR VTVM - need probes - where to buy?
"Chuck Harris" wrote in message ... wrote: On Sep 4, 12:03 pm, "Chuck" wrote: Richard is correct. May I add that my HP400H, the model with linear scales, was full of black plastic encapsulated paper capacitors (sometimes called bumblebees or black beauties). These capacitors are well known for their failure rates. There may be a reason you got a good price on your meter. "Cheap" meaning free is about the best price one can obtain. Shouldn't be hard to replace the caps, right? Am I missing something here? Nope, very easy. Just don't use disk ceramics. Something in a polyester, or polypropylene would do nicely. I am curious why you recommend against using disc ceramics. BB's are found in a lot of high-quality equipment. They were supposed to be high-performance deluxe caps when they were sold but very quickly got a well deserved bad reputation. -- --- Richard Knoppow Los Angeles, CA, USA |
New owner of HP 410LR VTVM - need probes - where to buy?
Richard Knoppow wrote:
here? Nope, very easy. Just don't use disk ceramics. Something in a polyester, or polypropylene would do nicely. I am curious why you recommend against using disc ceramics. BB's are found in a lot of high-quality equipment. They were supposed to be high-performance deluxe caps when they were sold but very quickly got a well deserved bad reputation. Disk ceramics, particularly Z5U, or X7R, are a bad idea in any signal path. The feature that gives them high capacitance for their size also makes them highly piezoelectric: meaning they change physical dimension with applied voltage. This large change in dimension makes the capacitance non linear with voltage, and also makes the capacitor's power dissipation change with applied signal. That means distortion. NPO's behave ok, but are of such low values that they would never be able to substitute for a capacitor such as a BB. I have used Z5U ceramic capacitors in high signal areas and actually heard them "sing" along with the signal. Not a good thing! Their capacitance is also extremely sensitive to temperature, which makes them useless in most timing applications. [I did use one once as a temperature transducer in a cheapy RF telemetry device...] They work adequately in logic circuits as power supply bypass. BB's are actually a pretty good capacitor, but they have a couple of failure mechanisms that render them useless over time. They are an oil filled paper capacitor with a black epoxy case. If you look at the banded end of the capacitor, you will notice the lead has a bulge where it leaves the case. That is actually a piece of brass tubing that was used in filling the case with oil. After the case was filled, the lead was stuck into the hole, swaged to keep it from falling out, and then soldered shut. The problem comes when the BB's banded lead is soldered into the circuit. If no heatsinking is used, the solder seal melts, and the oil spoils the seal. From that point forward, the oil will seep out of the capacitor, and moist air will seep in... it's a slow process that takes many thermal cycles, but we are talking about old stuff here. The other failure mechanism is the plastic case shrinks over time and breaks the seal around the leads, and sometimes even splits the case into pieces. The BB's are all bad by now, and should be replaced on sight, but when they were new, they were a nice high performance capacitor. -Chuck |
New owner of HP 410LR VTVM - need probes - where to buy?
"Chuck Harris" wrote in message ... Richard Knoppow wrote: here? Nope, very easy. Just don't use disk ceramics. Something in a polyester, or polypropylene would do nicely. I am curious why you recommend against using disc ceramics. BB's are found in a lot of high-quality equipment. They were supposed to be high-performance deluxe caps when they were sold but very quickly got a well deserved bad reputation. Disk ceramics, particularly Z5U, or X7R, are a bad idea in any signal path. The feature that gives them high capacitance for their size also makes them highly piezoelectric: meaning they change physical dimension with applied voltage. This large change in dimension makes the capacitance non linear with voltage, and also makes the capacitor's power dissipation change with applied signal. That means distortion. NPO's behave ok, but are of such low values that they would never be able to substitute for a capacitor such as a BB. I have used Z5U ceramic capacitors in high signal areas and actually heard them "sing" along with the signal. Not a good thing! Their capacitance is also extremely sensitive to temperature, which makes them useless in most timing applications. [I did use one once as a temperature transducer in a cheapy RF telemetry device...] They work adequately in logic circuits as power supply bypass. BB's are actually a pretty good capacitor, but they have a couple of failure mechanisms that render them useless over time. They are an oil filled paper capacitor with a black epoxy case. If you look at the banded end of the capacitor, you will notice the lead has a bulge where it leaves the case. That is actually a piece of brass tubing that was used in filling the case with oil. After the case was filled, the lead was stuck into the hole, swaged to keep it from falling out, and then soldered shut. The problem comes when the BB's banded lead is soldered into the circuit. If no heatsinking is used, the solder seal melts, and the oil spoils the seal. From that point forward, the oil will seep out of the capacitor, and moist air will seep in... it's a slow process that takes many thermal cycles, but we are talking about old stuff here. The other failure mechanism is the plastic case shrinks over time and breaks the seal around the leads, and sometimes even splits the case into pieces. The BB's are all bad by now, and should be replaced on sight, but when they were new, they were a nice high performance capacitor. -Chuck OK about the ceramics. I think there must have been two series of Black Beauty caps. Not all are oil filled. The ones I removed from an SP-600-JX for instance, are paper impregnated with polyester plastic. They are dry and don't have filler tubes. I suspect the main failure mode for these is due to the incapsulation. Many seem to have cracked and even those which have not cracked often have low capacitance and high dissipation factor. The capacitor winding is usually physically distorted, flattened for instance. I suspect that the case shrinks distoring it and also may allow moisture to enter. These caps were supposed to be much better than the wax coated paper caps of the time. Sprague also made a similar capacitor, that is a dry polyester impregnated paper cap, but in epoxy-dipped casings called Orange Drops. AFAIK, these have proven quite reliable and long lived, giving some support to my idea that it was the molded cases of the BBs that failed. BBs are found in a lot of high-quality equipment, General Radio, Hewlett-Packard, etc, used a lot of them. -- --- Richard Knoppow Los Angeles, CA, USA |
New owner of HP 410LR VTVM - need probes - where to buy?
Richard Knoppow wrote:
"Chuck Harris" wrote in The BB's are all bad by now, and should be replaced on sight, but when they were new, they were a nice high performance capacitor. -Chuck OK about the ceramics. I think there must have been two series of Black Beauty caps. Not all are oil filled. The ones I removed from an SP-600-JX for instance, are paper impregnated with polyester plastic. They are dry and don't have filler tubes. I suspect the main failure mode for these is due to the incapsulation. Many seem to have cracked and even those which have not cracked often have low capacitance and high dissipation factor. The capacitor winding is usually physically distorted, flattened for instance. I suspect that the case shrinks distoring it and also may allow moisture to enter. These caps were supposed to be much better than the wax coated paper caps of the time. Sprague also made a similar capacitor, that is a dry polyester impregnated paper cap, but in epoxy-dipped casings called Orange Drops. AFAIK, these have proven quite reliable and long lived, giving some support to my idea that it was the molded cases of the BBs that failed. BBs are found in a lot of high-quality equipment, General Radio, Hewlett-Packard, etc, used a lot of them. There are Black Beauties, and there are Black Beauties! The oil filled Black Beauties, in my experience, always have color coded bands that tell the ratings. They were a premium capacitor, and as such were quite expensive. The polyester dielectric capacitors have black bodies, with red lettering. I recall that they came out after the oil filled capacitors. Orange drops were a step up from the waxed paper capacitors, and a step down from the molded polyester black beauties. They were designed especially for printed circuit board use. Orange drops were a relatively cheap "jobber" capacitor, but they have certainly withstood the test of time quite well. -Chuck |
New owner of HP 410LR VTVM - need probes - where to buy?
"Chuck Harris" wrote in message ... Richard Knoppow wrote: "Chuck Harris" wrote in The BB's are all bad by now, and should be replaced on sight, but when they were new, they were a nice high performance capacitor. Snipping here... -Chuck There are Black Beauties, and there are Black Beauties! The oil filled Black Beauties, in my experience, always have color coded bands that tell the ratings. They were a premium capacitor, and as such were quite expensive. The polyester dielectric capacitors have black bodies, with red lettering. I recall that they came out after the oil filled capacitors. Orange drops were a step up from the waxed paper capacitors, and a step down from the molded polyester black beauties. They were designed especially for printed circuit board use. Orange drops were a relatively cheap "jobber" capacitor, but they have certainly withstood the test of time quite well. -Chuck All the BBs I've seen had colored stripes indicating the capacitance value and other data. These were dry caps. Not dried out oil-filled, there was no trace of oil or means of adding it. According to Sprague advertising of the time (early 1960s) the BB and Orange Drop had identical construction other than the encapsulation and radial leads on the ODs. I don't have catalogue info giving prices. The ODs were evidently made for printed circuit installation as you say and were probably smaller due to the dipped rather than molded case. I am not sure what the case of the BBs is made of, it appears to be a resin plastic such as Bakelite which was widely used at the time. Bakelite can shrink and depends very much on the filler used for longevity. They may have been made of something else. In any case, its of academic interest now. I remember having been warned not to use BBs as early as highschool, meaning the late 1950's. Also, the Hammarlund receivers began to be rebuilt with disc ceramics about the late 1950's so the trouble must have shown up within a few years. Sprague continued building the cap so, perhaps, the cause of the problem was discovered. They _should_ have been a superior capacitor. Too bad. -- --- Richard Knoppow Los Angeles, CA, USA |
New owner of HP 410LR VTVM - need probes - where to buy?
Richard Knoppow wrote:
All the BBs I've seen had colored stripes indicating the capacitance value and other data. These were dry caps. Not dried out oil-filled, there was no trace of oil or means of adding it. Richard, All BB's with color bands made in the late 40's, through the '50s were oil filled. The filler was not all that obvious unless you knew what you were looking at. It looks like a little solder ball on the banded lead where it enters the case. The cases look like bakelite, but I am not sure that they are. Bakelite requires high temperature and high pressure to cure (hence the "bake"). I don't think that would be good for a plastic dielectric capacitor. By the early '60s Sprague had thoroughly taken a drubbing over the failures of the BB's, and changed them to be a plastic dielectric, like the OD's. I don't think I have ever found a bad OD; nor have I ever found a bad BB that wasn't of the oil filled variety. -Chuck According to Sprague advertising of the time (early 1960s) the BB and Orange Drop had identical construction other than the encapsulation and radial leads on the ODs. I don't have catalogue info giving prices. The ODs were evidently made for printed circuit installation as you say and were probably smaller due to the dipped rather than molded case. I am not sure what the case of the BBs is made of, it appears to be a resin plastic such as Bakelite which was widely used at the time. Bakelite can shrink and depends very much on the filler used for longevity. They may have been made of something else. In any case, its of academic interest now. I remember having been warned not to use BBs as early as highschool, meaning the late 1950's. Also, the Hammarlund receivers began to be rebuilt with disc ceramics about the late 1950's so the trouble must have shown up within a few years. Sprague continued building the cap so, perhaps, the cause of the problem was discovered. They _should_ have been a superior capacitor. Too bad. |
New owner of HP 410LR VTVM - need probes - where to buy?
"Chuck Harris" wrote in message ... Richard Knoppow wrote: All the BBs I've seen had colored stripes indicating the capacitance value and other data. These were dry caps. Not dried out oil-filled, there was no trace of oil or means of adding it. Richard, All BB's with color bands made in the late 40's, through the '50s were oil filled. The filler was not all that obvious unless you knew what you were looking at. It looks like a little solder ball on the banded lead where it enters the case. The cases look like bakelite, but I am not sure that they are. Bakelite requires high temperature and high pressure to cure (hence the "bake"). I don't think that would be good for a plastic dielectric capacitor. By the early '60s Sprague had thoroughly taken a drubbing over the failures of the BB's, and changed them to be a plastic dielectric, like the OD's. I don't think I have ever found a bad OD; nor have I ever found a bad BB that wasn't of the oil filled variety. -Chuck Well, I don't know. The BB's I've gotten from Hammarlund receivers and some other equipment date from the mid 1950's and are definitely not oil-filled nor do they have the filler tubes. I've taken them apart: the dielectric is paper impregnated with plastic. It looks a little like the very fine paper used in Chinese cooking, thin and translucent. These all have stripes on them and no printing. Some of these have a thick end from the way the end leads are fastened to the foil. I really think there must have been two versions of the BB series. Perhaps the plastic type was a replacement for the oil-filled kind. They would have been easier to make and free from leakage. All the BBs I've check on a capacitance bridge, even those which appear new, have somewhat low capacitance and somewhat high dissipation factor. Of course, both could be accounted for if they were actually oil filled and the oil is gone to the extent of leaving no trace whatever. It would be interesting to know what the molded cases were actually made of. The material does not quite look like Bakelite but there were many variations of resins sold as Bakelite and under other names like Durez. Old catalogue date could answer some of these questions. -- --- Richard Knoppow Los Angeles, CA, USA |
New owner of HP 410LR VTVM - need probes - where to buy?
Richard Knoppow wrote:
I don't think I have ever found a bad OD; nor have I ever found a bad BB that wasn't of the oil filled variety. -Chuck Well, I don't know. The BB's I've gotten from Hammarlund receivers and some other equipment date from the mid 1950's and are definitely not oil-filled nor do they have the filler tubes. I've taken them apart: the dielectric is paper impregnated with plastic. It looks a little like the very fine paper used in Chinese cooking, thin and translucent. These all have stripes on them and no printing. Some of these have a thick end from the way the end leads are fastened to the foil. I really think there must have been two versions of the BB series. Perhaps the plastic type was a replacement for the oil-filled kind. They would have been easier to make and free from leakage. All the BBs I've check on a capacitance bridge, even those which appear new, have somewhat low capacitance and somewhat high dissipation factor. Of course, both could be accounted for if they were actually oil filled and the oil is gone to the extent of leaving no trace whatever. It would be interesting to know what the molded cases were actually made of. The material does not quite look like Bakelite but there were many variations of resins sold as Bakelite and under other names like Durez. Old catalogue date could answer some of these questions. Hi Richard, My experience with BB's is primarily with Tektronix and HP equipment from the very late 1940's to the early 1960's. They both used the banded BB's, and they were all oil filled. After the oil filled BB's failed in droves, Sprague changed the BB's to a plastic dielectric, which is, I believe, what you have seen. There might have also been a difference depending on the WV rating of the capacitor. The oil caps were 600V rated as I recall. I have never seen an oil filled BB, that had failed, that wasn't all fuzzy and goopy on the outside. The mineral oil definitely didn't just evaporate. -Chuck |
New owner of HP 410LR VTVM - need probes - where to buy?
"Chuck Harris" wrote in message ... Richard Knoppow wrote: I don't think I have ever found a bad OD; nor have I ever found a bad BB that wasn't of the oil filled variety. -Chuck Hi Richard, My experience with BB's is primarily with Tektronix and HP equipment from the very late 1940's to the early 1960's. They both used the banded BB's, and they were all oil filled. After the oil filled BB's failed in droves, Sprague changed the BB's to a plastic dielectric, which is, I believe, what you have seen. There might have also been a difference depending on the WV rating of the capacitor. The oil caps were 600V rated as I recall. I have never seen an oil filled BB, that had failed, that wasn't all fuzzy and goopy on the outside. The mineral oil definitely didn't just evaporate. -Chuck It seems to me I've also seen some BB's with oil on the surface and maybe dripping. At some point I will have to see what I can find in the library to try to date the change in design. -- --- Richard Knoppow Los Angeles, CA, USA |
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