Scored some NOS chokes today (in their boxes with the wax paper wrapping in tact). Each has 2 x 25 henry chokes (and instructions for series or parallel). Any guesses to how much current could be run thru them?
How do you actually measure current capability?
Southwestern Industrial Electronics Co, Huston TX. Model KC5005
dave
How do you actually measure current capability?
Southwestern Industrial Electronics Co, Huston TX. Model KC5005
dave
Attachments
A brace of choke!
Guestimate
200mA (sections in series)
As for testing, can only think of a contrived way to test (an actual circuit).
Someone must know an easier way....
You might also want to know whether they are suitable for choke-input use as well; eg whether they can stand some DC without loosing too much inductance and buzzing.
What is their DC resistance?
Time for a nice valve amp I think Dave....
Cheers,
Guestimate
200mA (sections in series)
As for testing, can only think of a contrived way to test (an actual circuit).
Someone must know an easier way....
You might also want to know whether they are suitable for choke-input use as well; eg whether they can stand some DC without loosing too much inductance and buzzing.
What is their DC resistance?
Time for a nice valve amp I think Dave....
Cheers,
Hello Take care i once destroyed some black Gate with a choke input with a surplus choke. If you will not use it for a choke input you can try to give it a try with a modest current and check the temperature from time to time. Maybe they are meant for aviation industry ( 800 cycles ) I would anymore go to a person with enough equipment to have them tested Succes, Ed
Re: Re: A brace of choke!
man that a low DCR... given the size are you sure you didn;t miss a decimal on the 25hy... .25hy seems much more believable.
just for reference a 20hy 150ma choke about that size has a DCR of 300 ohms.... and remember the two 25 hy chokes in series is 100hy!!! a 100hy choke with an 18 ohm DCR seems very unlikely.
if they are indeed 2X25hy, i wouldn't expect them to handle much DC... or AC for that matter.
dave
dave
planet10 said:
man that a low DCR... given the size are you sure you didn;t miss a decimal on the 25hy... .25hy seems much more believable.
just for reference a 20hy 150ma choke about that size has a DCR of 300 ohms.... and remember the two 25 hy chokes in series is 100hy!!! a 100hy choke with an 18 ohm DCR seems very unlikely.
if they are indeed 2X25hy, i wouldn't expect them to handle much DC... or AC for that matter.
dave
dave
9R is a very low DC resistance for a stated 25H inductance. The only way I can see of achieving two of those in a can that size is not to gap the core, making the DC current rating zero. I suspect that these chokes were made to be part of a signal filter, not a power supply - they have a telecomms look about them, particularly with the paint masked from the mounting surface.
What makes a choke buzz? My new amp buzzes, and I'm not sure which piece of iron in there is doing it. I haven't really bothered with fixing it because I can't hear it over the music, but it would be nice if it could be fixed.
I'm also wondering if I should bother about the hum. I can only hear it late at night with no music playing, and I'd need 3 new transformers to convert all my heaters to DC, I think. My RS DMM says 2mV, my scope is uncalibrated so I don't trust what it says.
Hi,
Crud from the mains is one source, badly implemented ground another amongst a dozen.
Oh, and if your mains xformers are toroids you can say hello to a lot of that aggrevating buzzing too.
That would bother me no end...your noisefloor becomes too high for comfort and it make soundstage depth colapse.
Does it happen with the input of the amp shorted?
Cheers,
Crud from the mains is one source, badly implemented ground another amongst a dozen.
Oh, and if your mains xformers are toroids you can say hello to a lot of that aggrevating buzzing too.
That would bother me no end...your noisefloor becomes too high for comfort and it make soundstage depth colapse.
Does it happen with the input of the amp shorted?
Cheers,
I'm just starting to get over being dazzled by how much better this amp is than what I had before
So I'll start fixing/changing things on it soon. I tried the caps from B+ to cathode using clip leads, and while they didn't lower the noise floor, the sound did improve. I also need to reduce the filament voltage on my 6SL7s a little (it's about 7.1V, IIRC), and change a few other things.Well, it could certainly be the second. Any specific grounding issues that I should look at? And how would I test for mains noise? I have a small cap across the transformer primary. Also, I don't know if it's the choke that's buzzing or the power trasformer or the filament transformers.
No toroids.
Haven't tried that yet. I'll try it tonight.
This is what the design called for (though I've modified the PSU from the original design):
This is what I used:
Increased current handling and lower DCR for a lower price, made sense to me. These are Hammond chokes, the prices are from the Angela website. Here's my PSU:
This is what I used:
Increased current handling and lower DCR for a lower price, made sense to me. These are Hammond chokes, the prices are from the Angela website. Here's my PSU:
An externally hosted image should be here but it was not working when we last tested it.
Choke spec:
http://www.hammondmfg.com/193.htm
Doesn't say it'll work on choke input. But your circuit has a small but reasonable first cap. I wouldn't expect a problem.
Cheers,
http://www.hammondmfg.com/193.htm
Doesn't say it'll work on choke input. But your circuit has a small but reasonable first cap. I wouldn't expect a problem.
Cheers,
Thanks. I could try temporarily increasing the cap to see if the buzzing goes away, but that will upset all the voltages. And I'd rather not use resistors to adjust the voltages - they'd have to be rated for pretty high power, and it seems to me that the more series resistance I have, the more the PS output will sag during high current transients.
Just making sure I understand this - in a choke input filter, the choke sees much higher current surges, because the first cap that's charging up comes after it. In a cap input filter, the current surges through the choke are smaller. Thus, even if the choke's current rating (200mA - that's DC, right?) fits the circuit, it might not work with a choke input filter. Is that correct?
Also, the 800VDC rating - voltage between what and what? The drop across the choke itself is fairly small. Is it the voltage between the windings and the enclosure (which may be grounded to teh chassis)?
Just making sure I understand this - in a choke input filter, the choke sees much higher current surges, because the first cap that's charging up comes after it. In a cap input filter, the current surges through the choke are smaller. Thus, even if the choke's current rating (200mA - that's DC, right?) fits the circuit, it might not work with a choke input filter. Is that correct?
Also, the 800VDC rating - voltage between what and what? The drop across the choke itself is fairly small. Is it the voltage between the windings and the enclosure (which may be grounded to teh chassis)?
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