what am i suppose to do with all these air variable caps?

[ssbothwell SWL]

i found some really crazy deals on air variable caps this week. i got a bunch of smaller caps from the electronics junk yard a couple days ago for maybe $15 or $20 and then today i got some big ones for $2 each at the ham swap meet (W6TRW).

heres a photo: http://i.imgur.com/iCcXw.jpg

what should i do with all of these?

also, two of the big ones have ceramic spacers which are cracked. what should i use to repair them?

[Ed/KB1HYS]

Hmm, well the smaller ones look perfect for making regenerative receivers with. Or with the dual gang ones you could build a super het.   Also a couple look like they'd be good in a VFO.

As for the big ones, well... those would work in a lot of different transmitter circuits.

[K5UJ]

also, two of the big ones have ceramic spacers which are cracked. what should i use to repair them?

Hard to say for sure without getting a close look but the two ton clear crystal epoxy might hold the ceramic, or maybe nothing needs to be done-it depends on what kind of force is on the spacers.  Just don't use JB Weld as I have been told it does not have an insulating property at RF.

[WBear2GCR]

Obviously, you will need to get yr license and use these in either a simple xmitr or perhaps a tuner... the smaller one(s) in a VFO circuit?

Imo, if the cracks do not effect the unit mechanically, leave it alone.

Run them through the dishwasher - they will clean up nicely.

                    _-_-bear

[kg8lb]

 Take them to Dayton . No, they won't sell but when you toss them in the dumpster at the end of the show the dumpster divers will look like a flock of seagulls on fishguts . Fun to see in a disgusting kind of a way 

[ssbothwell SWL]

thanks for all the ideas. i think i am going to use one in a loop antenna for reception and see if it works better than a longwire for my grundig g5. what size cap would be most appropriate?

are the really big ones just designed to tolerate higher voltages? i believe they have similar capacitance values to the medium sizes one in that photo. what would the big ones be most useful for?

Obviously, you will need to get yr license and...

i'm working on that. i recently emailed a local club asking about exams and they referred me to the arrl section manager. hopefully this will happen soon.

[k4kyv]

Take them to Dayton . No, they won't sell but when you toss them in the dumpster at the end of the show the dumpster divers will look like a flock of seagulls on fishguts . Fun to see in a disgusting kind of a way 

No, smash them with a sledge-hammer first, to make sure no dumpster diver will ever get his putrid hands on them.

2-ton crystal-clear epoxy is a good rf insulator. I have even used it as coil dope for KW plate tank coils.  JB Weld is conductive because it uses iron dust as a filler. You can actually feel the attraction of a strong magnet to a blob of cured JB Weld.

[W2PFY]

Looking at those larger caps I see uneven spacing between the plates. I have seen this on surplus gear installed and working. If they were to be used in a HV setting, I would center the rotor in relationship with the fixed plates. I wonder if this is done on purpose to get more capacity in uuf out of the caps?

[k4kyv]

I would say they got banged around, or the nuts worked loose, and someone carelessly tightened them up. I have seen brand new caps with uneven plate spacing, and sometimes the rotor plates have slipped (rotated) relative to each other so they are not all lined up perfectly with each other. It is a tedious process, but if I am using a cap near to its maximum voltage rating, I carefully try to re-align all the plates. Sometimes that requires bending stator and/or rotor plates slightly in such a manner as to get them to stay centred throughout 180° of rotation. It takes a little patience. Get some of them aligned perfectly, and it may throw others out of  alignment. Or get them all aligned at full mesh, and when you rotate towards minimum capacitance, some will be off.

I suspect in many cases they were never perfectly aligned ever, even as they came out of the factory.

Misaligned plates will not increase the capacitance unless they are off so far as to be almost touching. If they are just slightly off, the gap on one side of the misaligned plate will be spaced more closely, but the gap on the opposite side of the same misaligned  plate will have greater spacing, resulting in negligible change in total capacitance, but the maximum voltage rating is still degraded.

[kg8lb]

Take them to Dayton . No, they won't sell but when you toss them in the dumpster at the end of the show the dumpster divers will look like a flock of seagulls on fishguts . Fun to see in a disgusting kind of a way 

No, smash them with a sledge-hammer first, to make sure no dumpster diver will ever get his putrid hands on them.

  I knew you would have a better idea there Don 
Good plan , you not only see the feeding frenzy but you get to learn a few new curse words as well !

[ssbothwell SWL]

i think the alignment looks worse in that photo than in real life. here is a slightly a better picture of the four big capacitors. the one on the bottom right is pretty banged up but the other 3 pretty straight.

other than physical damage, how do you guys determine the quality of a variable cap? i'm sure these lose points for not having bearings (other than the top right one) but otherwise they look like any other variable cap i have seen.

[KD6VXI]

thanks for all the ideas. i think i am going to use one in a loop antenna for reception and see if it works better than a longwire for my grundig g5. what size cap would be most appropriate?

are the really big ones just designed to tolerate higher voltages? i believe they have similar capacitance values to the medium sizes one in that photo. what would the big ones be most useful for?

Obviously, you will need to get yr license and...

i'm working on that. i recently emailed a local club asking about exams and they referred me to the arrl section manager. hopefully this will happen soon.

The bigger ones are rated for both higher voltage and RF current ratings.


--Shane
KD6VXI

[Opcom]

Take them to Dayton . No, they won't sell but when you toss them in the dumpster at the end of the show the dumpster divers will look like a flock of seagulls on fishguts . Fun to see in a disgusting kind of a way  

No, smash them with a sledge-hammer first, to make sure no dumpster diver will ever get his putrid hands on them.

There was a Johnson 122 VFO that came into my hands a couple years ago. It was really rough, almost all the paint seemed to be scratched off. The story is that some ham had it at a fester, and was unhappy because no one wanted to pay his price (no idea what that was). The tale is that he tied the ac cord to his trailer hitch and drove off, dragging the poor thing through the parking lot out of spite. The cord broke and someone who'd seen this felt so much grief at the rage unjustly apportioned to the innocent little thing that he grabbed it as the unhappy fellow (no doubt cackling insanely) drove off.

As to the caps needing repair or alignment, A good "instructable" could be made of repairing a capacitor, taking pics before, and of each operation, to the finish. Showing this kind of thing is a good way to promote hands-on electronics, which is lacking as a handy skill today. I did one on a small single-bearing air variable. It does not have a huge number of views but some is better than none and maybe it helped someone else.

[k4kyv]

There was a Johnson 122 VFO that came into my hands a couple years ago. It was really rough, almost all the paint seemed to be scratched off. The story is that some ham had it at a fester, and was unhappy because no one wanted to pay his price (no idea what that was). The tale is that he tied the ac cord to his trailer hitch and drove off, dragging the poor thing through the parking lot out of spite. The cord broke and someone who'd seen this felt so much grief at the rage unjustly apportioned to the innocent little thing that he grabbed it as the unhappy fellow (no doubt cackling insanely) drove off.

Something even more pathetic is the fact that corporations sometimes have that same attitude. In a conversation on the air, someone once related how he worked for a company that had been in business for decades. They were emptying out a storage room that was filled with n.o.s. 1930s vintage tubes left over from some long-forgotten project, and instructions were to take them all to the dumpster. He mentioned to the supervisor that he could use some of them in his radio equipment, and asked if he could take them home instead of dumping them. The boss's reply was essentially, "hell no, I'm not giving away company property to anyone". He even offered to purchase them, but the boss wasn't interested. That evening as he left work, he had planned to pull them out of the dumpster on his way home, but found that it was padlocked.

[KX5JT]

The boss's reply was essentially, "hell no, I'm not giving away company property to anyone". He even offered to purchase them, but the boss wasn't interested. That evening as he left work, he had planned to pull them out of the dumpster on his way home, but found that it was padlocked.

I think that's really strange!  He, i.e. the corporation, probably could have gotten some sort of tax benefit for donating the stuff.   All this goes to show that we can't control the other person, only ourselves.  Heartbreaking sometimes isn't it.

[Ed/KB1HYS]

Years ago, the company I work for used to actually let employees purchase surplus or 'uneconomical to repair' equipment.  unfortunately some unscrupulous types found that they could disable some really expensive (at the time) scopes, by a simple fault like clipping a lead or some such and get them declared non-repairable.  Then they would move in make the buy, and flip it.   Sadly this put an end to the practice.  The company doesn't throw it out however, they have a contract with a couple of surplus houses that buys up the stuff in big lots. 

[kg8lb]

 One auto manufacturer used to give tires and other no longer needed pull-off parts from their prototype/experimental cars to the employees. This practice went on for many years. At some point in the late 1970s a set of the tires wound up in a non employee's hands. That person experienced a blow out and successfully sued the automaker. All scrapped tires are now cut through the beads or hole sawed in the sidewall.
  When I worked at Sun Electric Corporation we took test stands in on trade. The trade ins lanquished in the back room for one year. Upon the first anniversary in storage the stands were taken into the alley and destroyed totally and summarily put into the dumpster. The meters, gauges and tubes were especially targeted. The reason for the destruction was the trade ins were written off on the tax rolls after recording serial numbers. If a declared machine were ever to show up in use the company could have been guilty of tax fraud. They took no chances . Further they did not want to afford dumpster divers with a source of free replacement parts so all critical service parts were destroyed.

Would be dumpster diver/thieves are often kept honest VIA a padlock ! It is the right of the owner to insure their wishes regarding disposal are carried out .

  Recall watching a car load of scrap leaving a local junkyard a couple of years ago . The owner noted a bumper on the pile and said to his son "That looks like a pretty good 1970 Nova bumper !" His son said "Yes it is" The dad asked why it was on the truck and junior replied "Because for 30 plus years no one wanted it." Yep it ate up space, produced nothing for 30+ years .

  Just facts  of life.

 Interesting to read the  comment about the poor little VFO . Very funny indeed ! Lucky it came off in the parking lot and not on the road. Maybe it just got tangled by the cord by accident however ? Hard to say.

  Of course I was kidding about throwing the stuff out at Dayton but smashing it was Don's suggestion  
I never toss anything out at hamfests  

[KE6DF]

JB Weld is conductive because it uses iron dust as a filler. You can actually feel the attraction of a strong magnet to a blob of cured JB Weld.

Ouch. I just "fixed" the broken ceramic insulator on a neutralization cap with JB Weld. Oh Well.

[k4kyv]

Would be dumpster diver/thieves are often kept honest VIA a padlock ![/b] It is the right of the owner to insure their wishes regarding disposal are carried out .

Dumpster diving is not the same thing as theft.  It is nothing more than taking or rescuing abandoned property, nothing "dishonest" about that; dumpster divers are not depriving the former owner of anything whatsoever. In fact, (as long as they don't leave litter on the ground next to the dumpster) they (we) are performing a public service by helping to preserve landfill space and extend the time before the landfill has to be closed out at public expense. Except perhaps in cases involving HAZMAT or something that might later be used against the former owner for (or as evidence of) criminality (items like toxic chemicals, personal records and old hard drives, which should not be going into publicly accessible trash anyway), why should anyone even care what happens to stuff once they toss it in a dumpster? A person who would become upset over the possibility of someone else making use of his/her discarded property is an example of a small-minded individual with a negative attitude walking round with a chip on his shoulder, someone who needs to get a life.

Of course I was kidding about throwing the stuff out at Dayton but smashing it was Don's suggestion  
I never toss anything out at hamfests

So was I.  I was being facetious, seeing that Gary took up for that fool who applied a sledgehammer to the Hallicrafters amplifier and posted the video on YouTube.  I would never seriously advise the same kind of spitefulness as demonstrated by that guy or the one at the hamfest with the VFO.

I have done my share of picking stuff out of the trash at the conclusion of hamfests; occasionally, items I would have gladly purchased if I hadn't missed seeing them on the vendor's table, otherwise, something I had too little interest in to pay money for, but which still had enough redeeming value to take for free: maybe one of the knobs matched a missing one on my equipment, or something I didn't need yet a freebie junker would be worthwhile to lug home as a quick source of otherwise unobtanium parts.

This past year at Dayton, Saturday afternoon within 2-3 hours of closing time and all day Sunday, one didn't have to pull stuff out of the trash.  Many vendors simply departed from the flea market and left behind, on the ground, what they didn't want to haul back home. I picked up a couple of 12" speakers still marked "$50 each" and a small plate transformer that way.

Instead of trashing items that aren't selling or simply not worth the trouble, some vendors have a better idea: mark "free" and set them conspicuously in front of their booth. More than once, I have found real treasures in the "free" boxes under vendors' tables, and the seller smiled when I thanked him as I walked away with an armload. Destroying something just to prevent someone else from using it is a symptom of the same kind of spitefulness as the guy at the hamfest with the VFO. Just as with dumpster finds, people often don't have a clue what they are throwing out or giving away. It would be a real shame for that kind of stuff to be destroyed out of spite and/or ignorance.

Here's a funny story I once heard, regarding the reverse bandit at a hamfest. He was about ready to leave but still had a bunch of unsold items, so he took them down the flea market corridors one at a time, and when no-one was looking, nonchalantly deposited them in other vendors' spaces amongst their displayed wares and quietly walked away.  

[kg8lb]

   BTW Don, I did not take up for the fool on youtube other than to say it was pretty stupid but he had every right to do what he did. I said I got a bigger kick out of the rancerous, hatefilled responses.  I did not advocate for the actions but supported the right. I further inferred that by responding at all to the video people were giving the fellow exactly what he hoped for..attention. Negative or positive his goal was attention and the folks played right into his hand.



  In the case of disposal , there are indeed instances where the party disposing of materials has every interest in keeping them out of the hands of others. They need not explain nor disclose the motivation . Once it is clear that they expect disposal , that is their right. As I stated regarding the Sun Electric equipment, they did not care to allow people to cut short parts sales by getting scraps from the dumpster.There is also the issue of liability. In this law suit happy society a person injured from materials plucked from trash could make a case with sympathetic jurists and secure recovery. There are security /proprietary issues as well. For whatever reason the people want the materials scrapped they have every right to expect that and yes, thwarting that right is theft..period.
 They owe no explanation nor apology. They are due respect for their wishes and rights. Dumpster diving is not a right.

  I have no chip on my shoulder, carry no grudges . I leave that for others .Perhaps the small minded individuals who may choose to attack others for exercising their property rights for example ?


 Don, I understood you were being facetous I was hoping all along that you would have realized I was doing same.I have very  often take up  the reverse dumpster diving thing , I call it "maniac-clepto" where I take tubes, sockets cable whatever to a buddie's table and leave it there . Also mark goods as "free" or when someone spots something and actually picks it up as though he wants it I very often say "You picked it up, it is yours"..Free. I do that quite often. People who actually KNOW me are well aware of this.    I have also, in the past done a lot of dumpster diving. In fact , when I came to work here I told them "Don't pay me a nickel, just let me pick through your scrap" I would make the same offer today ! As it is, dumpster divers may be fired and rightly so.

 

[WD8BIL]

The story is that some ham had it at a fester, and was unhappy because no one wanted to pay his price (no idea what that was). The tale is that he tied the ac cord to his trailer hitch and drove off, dragging the poor thing through the parking lot out of spite

This one wasn't done out of spite. It was a burned out ol' Viking warrier Skip couldn't unload.

Viking Drag

[w1vtp]

i think the alignment looks worse in that photo than in real life. here is a slightly a better picture of the four big capacitors. the one on the bottom right is pretty banged up but the other 3 pretty straight.

other than physical damage, how do you guys determine the quality of a variable cap? i'm sure these lose points for not having bearings (other than the top right one) but otherwise they look like any other variable cap i have seen.

How do you manage to upload a 0 KB jpg?

[k4kyv]

 In the case of disposal , there are indeed instances where the party disposing of materials has every interest in keeping them out of the hands of others. They need not explain nor disclose the motivation . Once it is clear that they expect disposal , that is their right. As I stated regarding the Sun Electric equipment, they did not care to allow people to cut short parts sales by getting scraps from the dumpster.There is also the issue of liability. In this law suit happy society a person injured from materials plucked from trash could make a case with sympathetic jurists and secure recovery. There are security /proprietary issues as well. For whatever reason the people want the materials scrapped they have every right to expect that and yes, thwarting that right is theft..period.
 They owe no explanation nor apology. They are due respect for their wishes and rights. Dumpster diving is not a right.

Yes, I understand what you are saying.  If someone trespasses on private property to pull stuff out of the dumpster, that would be an unlawful act if the property owner decided to press charges. But when something is disposed of in a public dumpster or landfill, or placed kerbside for garbage pick-up, it has become abandoned property, and the former owner no longer has any say-so over what happens to it. Dumpster divers are not unlike treasure hunters who salvage centuries-old sunken ships. That's why I would advise anyone to shred their bank statements, personal letters and other personal data before depositing it in the trash. If someone suffers identity theft or if family secrets become public knowledge because they threw sensitive information in the trash, they have no-one to blame but themselves, and share fault equally with the dumpster diver who happened to stumble upon the information and took advantage.

 I have no chip on my shoulder, carry no grudges . I leave that for others .Perhaps the small minded individuals who may choose to attack others for exercising their property rights for example ?
... Don, I understood you were being facetous I was hoping all along that you would have realized I was doing same.I have very  often take up  the reverse dumpster diving thing , I call it "maniac-clepto" where I take tubes, sockets cable whatever to a buddie's table and leave it there . Also mark goods as "free" or when someone spots something and actually picks it up as though he wants it I very often say "You picked it up, it is yours"..Free. I do that quite often. People who actually KNOW me are well aware of this.    I have also, in the past done a lot of dumpster diving. In fact , when I came to work here I told them "Don't pay me a nickel, just let me pick through your scrap" I would make the same offer today ! As it is, dumpster divers may be fired and rightly so.

Indeed I was fully aware that you were being facetious too. Please be assured that I was not referring to you personally, but to people like that supervisor who wouldn't sell or give away the old tubes simply because it was "company property", yet he valued it so little that he had them tossed into the dumpster and locked it up so no-one  could salvage it, or those two individuals, the guy with the Hallicrafters and the one with the VFO at the hamfest.  I have run into plenty of other people just like that all my life, mostly involving things unrelated to radio. I have to say that I hold such people in utter contempt, property rights or no property rights. One of the most notorious entities that carries this attitude is the government.  Just prior to WWII, a huge swathe of private property in this area was condemned by the feds so they could use the land for building the near-by army base. People whose houses were condemned were given a deadline to take their furniture and personal belongings, but were warned that if they removed light fixtures, wiring, door hardware, plumbing, etc. from their homes when they vacated, they would be charged with theft of government property. But the government did nothing with the vacant houses but burn them to the ground or use them for bombing practice. One gentleman I knew personally (now deceased), told me he had a very expensive chandelier, a family heirloom he had restored with his own hands and converted to accommodate electric lighting, but left in the house due to the directive.  When he returned to gather their last few personal items before the deadline, he discovered that the chandelier was already gone.

You will find few people more sympathetic to property rights than myself. In fact, one of the very few Supreme Court cases in which I can say I agreed with the vote cast by Clarence Thomas was the eminent domain case in CT, in which the majority of the Court ruled that a city may condemn the homes of residents in order to sell the property to another private entity that would allow the city to collect more money in property taxes.  That being said, I also adamantly defend the right to salvage abandoned property.

[KA2QFX]

It's strange what people do out of spite. I once saw a TS-440 on a table at Boxboro, MA.  It had been completely dismantled with all the sub-assemblies just held together by their wiring harnesses. I offered the guy $50 bucks as-is just for parts. He said "Hell no, I've got $100 in parts alone into the thing. I'll throw it in the dumpster before I'd let it go for $50." And that's exactly what he did with it, after trashing it thoroughly first. Go figure! 

As for the broken ceramic I've replaced said ceramic with salvaged soap stone and/or Lexan with excellent results. 

Mark

[KB2WIG]

You shudda walked up to him and said "I changed my mind, here is the hundred."


klc