[lord_glum]

2 questions...

Other than current draw and slight voltage difference, if i swap a 5Z3 for a GZ37 is there any other difference other than about $75?

I have a choke that is a 10mH choke, but i do not know the mA rating.  Other than the fact that it is the current rating, what difference does it make?  I have a 10mH Electra Print choke i want to use in a power supply that calls for a 150mA 10mH choke.  if by some chance my choke is not rated for 150mA, what will this do?

Thanks,
Jvo

[BillB]

Are you actually drawing 150ma of current?

Shouldnt it be H not mH also?

[JoshK]

I am not familiar with the 5Z3, but tubedata.org is your friend.  Look for maximum current, Vdrop at current draw, pinout, etc.  If your power supply is cap input and it has a big cap that the GZ37 can handle but the 5Z3 cannot, you might have problems.   Maybe if I have some time later I'll look it up and get back to you.

The choke Q:  inductance (mH) isn't a constant, it is rated for stated inductance at a particular current.  So your choke might be 10mH @150mA but 1H at 10mA.  Also, one needs to mind the voltage (insulation) ratings.  If you overdrive a choke (too much current) you will saturate the core and that results in a number of bad things like, but not limited to, poor bass response, humming, really bad sound.  Best thing to do is ask Jack @ electra-print.

[lord_glum]

My bad.  yes only henry's no milli henrys.  

The amp is more or less the JE labs 2a3.  My problem is i do not know what my choke is rated for.  

Jvo

[JoshK]

What kind of choke is it?  Where did you get it?

You might be able to guesstimate current rating if it was surplus or old stock and there is no way to find out otherwise.  You can measure the DCR, which will give you a pretty good guess (lower DCR usually means higher current rating), size of the choke and gauge of the wiring.

[lord_glum]

yeah...i thought of emailing jack (his website has changed since the last time i was there) but was debating how to word it.  

"yeah jack i bought a set of outputs trannies and a pair of 10H chokes about 5 years ago.  I was lazy and just built the amp this year, but i dont remember the model number of any of the parts so do you by chance have any more info...."

So i figure i would attempt to learn a bit more before i bugged him.  

Jvo

FYI I bought 2 based on the ray koonce time bandit 2a3.  They are electra print 10H chokes and i am guessing at 20 ga. wire.  based on the fact that they are hi quality chokes i think i will be ok using 1 of them.

[JoshK]

He should be able to tell you the choke ratings from the size, weight and DCR of the choke.

http://www.mif.pg.gda.pl/homepages/frank/sheets/129/g/GZ37.pdf
http://www.mif.pg.gda.pl/homepages/frank/sheets/021/5/5Z3.pdf

Looks like they are fairly close in ratings.  You should be fine as long as you aren't operating right at the peak capability since the 5Z3 has a PIV of 1400V versus 1600V for the GZ37, apart from the obvious difference in base.

I didn't notice the Vdrop.

[lord_glum]

The V drop only came from playing around with the power supply in duncan amps power supply disigner.  Other than price and wow factor i couldn't find any reason not to use the 5Z3 vs the GZ37.  I just wanted somebody smarter than me to make sure there wasn't something i was missing.

Jvo

[JoshK]

If you've modeled it in PSUDII then you've covered your bases.

[f2a]

the 5Z3 has a PIV of 1400V versus 1600V for the GZ37.

what is use of  piv  different in 2a3  currently circuits?5z3  is similar to 5u4  but different base and sound is nice .

[lord_glum]

So I got a hold of Jack.  It seems to be rated up for 125mA.  So now i am torn.  I am using the stereo JElabs 2A3, but i want to procure as little parts as possible.  I do not know if a single choke can handle the load.

So do I run both of them in parellel and modifiy the power supply section even more or buy a 10H 150mA choke?

Thanks,
Jeremy

[2wo]

Go ahead and use the choke, it should work just fine. So maybe you get 9.5H at 150ma. No big deal…John