eHam
eHam Forums => Amplifiers => Topic started by: VE7RF on January 23, 2023, 10:11:16 AM
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I'm not having much luck on e-bay. Either too expensive, not a high enough range, or only does AC.
I need something that will do 0-15 kv.....and preferably higher.
I see that CTR engineering lists a new 0-15 kv unit at a reasonable price..($250.00). They don't respond to my e-mail. Has anybody bought this unit? Are they still being made ? I need one...like yesterday.
https://www.ctrengineeringinc.com/hv-tester/
Tnx.... Jim VE7RF
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W8JI frequents the QRZ Amateur Radio Amplifiers forum.
Many years ago I built a 0-15 kV hipotter using a VW ignition coil and found it quite useful. Unfortunately I gave it away. For an off-the-shelf HV power model the Ultravolt 15A12 series is excellent and supplies 260 uA. Digikey stocks them for $525.
https://www.digikey.com/en/products/detail/advanced-energy/15A12-P4/10833192
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I still have a hi voltage probe to check crt hivoltage.I think it was made by fluke, you use it with a multimeter and divide by 10 or is it 100.
Maybe look for one of those as now cathode ray tubes tv sets are obsolete like the repair tools are.
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RWI, he's looking to make high voltage not measure it.
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This is my custom made, 10KV hipot tester. I used a 10kv furnace igniter.
(https://cdn-bio.qrz.com/x/n8cbx/hipot_1.jpg?p=f473391728e1fda80a85eeb45fa689ab)
Jan N8CBX
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BX:
Not only functional, but a piece of art too!
nice job. 8)
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I used 4x microwave diodes and 4x 0.001/15kv ceramic caps for the HV power supply. No fuse for the transformer, but used a 100w light bulb (if you can find 100W incandescent bulbs anymore)
Jan N8CBX
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Just got my new 0-15 kv dc hi-pot tester from Tom Rauch, W8JI at CTR engineering. It's a thing of beauty. Beautifully constructed.
Weighs nothing...maybe 1/2 lb at most. Only 3 .75" wide x 4.875" long x 2.5" thick. Operation is glass smooth. Meter reads 0-15 kvdc in 500 vdc increments. Red led denotes leakage current (ua).
I asked about inserting either a 0-50 ua meter in the external return lead......or my fluke 87 DVM, and use it on it's 0-400 ua scale..... which reads down as low as just .1 ua.
He said that's perfectly safe...as long as it's in the return leg. The idea here was to correlate red led brightness...with external fluke DVM readings.
Ok, now I have a ton of items to test with it. It requires external 12-18 vdc @ 300 ma applied to it's side jack.
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Another thing worth having is a resistor in the return lead of suitable value and an AF amplifier and speaker. Before things break down, the noise indicates ionisation in the dielectric under test, and it's more sensitive than a meter. My ionisation tester was a professional unit that needed a rebuild but only cost me $10. Very useful piece of kit!
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Another thing worth having is a resistor in the return lead of suitable value and an AF amplifier and speaker. Before things break down, the noise indicates ionization in the dielectric under test, and it's more sensitive than a meter. My ionization tester was a professional unit that needed a rebuild but only cost me $10. Very useful piece of kit!
What value and wattage resistor used ? Can you run a leads from both sides of the resistor, through a coupling caps, then into the riaa input of an audio amp ? (or bypass /remove the riaa input). My fluke goes as low as .1 ua. That seems pretty good for the meantime.
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Just got my new 0-15 kv dc hi-pot tester from Tom Rauch, W8JI at CTR engineering. It's a thing of beauty. Beautifully constructed.
Received mine over the weekend. Nicely constructed and a worthy companion to a 6 KV Megger model I've been using.
In addition, an inexpensive Eisco microammeter can be used with either device. It's a moving coil movement that measures from -20 uA to +100 uA. Zero is centered about a quarter of full scale.
Paul, W9AC
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Just got my new 0-15 kv dc hi-pot tester from Tom Rauch, W8JI at CTR engineering. It's a thing of beauty. Beautifully constructed.
Received mine over the weekend. Nicely constructed and a worthy companion to a 6 KV Megger model I've been using.
In addition, an inexpensive Eisco microammeter can be used with either device. It's a moving coil movement that measures from -20 uA to +100 uA. Zero is centered about a quarter of full scale.
Paul, W9AC
Tom indicated to use a 100k to 500k resistor in series with the hot side, when hi-pot testing stuff like grid to cathode on oxide tubes. I'm suggesting that may also be a good idea when testing vac variable caps. However, I'm not clear on what type of resistor should be used for this application. Does it need to be HV rated ? Can the resistor be in series with the return leg ?
I was testing a ton of stuff with it. ( Fluke 87 DVM in return lead, on it's 0-4000 ua scale) and when testing a jennings 50-4000 pf vac cap ( 5 kv rated)... I noticed it showed no leakage at 5 kv. But just a TINY bit above 5 kv..and poof, it arced the plates. It went from 0 ua, to aprx 7 ua to ARC. ( I had NO resistor in series with either leg) On some other items, the leakage current just keeps on increasing. On these other items, HV can be increased till leakage can be 50 ua. Then on my vac cap, it arcs with > 5-7 ua..... go figure.
So far, so good. But it really requires a ua meter in the return leg at all times.
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I'm suggesting that may also be a good idea when testing vac variable caps. However, I'm not clear on what type of resistor should be used for this application. Does it need to be HV rated ? Can the resistor be in series with the return leg ?
I don't think it matters unless there's noticeable flashing across the resistor. The tester holds current within microamp range and vacuum caps can easily pass amps of current with HV applied. So, I'm inclined to think that a resistor is necessary to protect against tube grid damage but it's unnecessary for vacuum cap testing.
Paul, W9AC
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I'm suggesting that may also be a good idea when testing vac variable caps. However, I'm not clear on what type of resistor should be used for this application. Does it need to be HV rated ? Can the resistor be in series with the return leg ?
I don't think it matters unless there's noticeable flashing across the resistor. The tester holds current within microamp range and vacuum caps can easily pass amps of current with HV applied. So, I'm inclined to think that a resistor is necessary to protect against tube grid damage but it's unnecessary for vacuum cap testing.
Paul, W9AC
You are right. 100ua X 100k ohms = 10 volts. 100 ua X 500k ohms = 50 volts.
Quality 3 watt mof resistors are good for 500 vdc. 1 ma X 500k = 500 vdc. It's a non issue really..and I don't own any oxide tubes.
Both Econco and JI did say, that if testing between anode to grid, to also temp bond the cathode to the grid (typ grid is grnded to chassis...so just temp chassis grnd the cathode). If testing between grid and cathode, bond the anode to the grid. (just temp bond the anode to the chassis).