Smoothing choke

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skal1

Well-known member
Joined
Jun 4, 2008
Messages
1,290
Location
Birmingham,uk
Ok i need a Smoothing choke stancor c-2327 

Specifications
Brand: Unspecified Hammond Manufacturing
Dimensions: - 1.5 in W x 2.81 in L x 1.69 in H
Inductance: - 1.5 H
Maximum DC Current: - 200 mA
Maximum DC Resistance: - 56 Ohms.


I can not get one from the UK but i have found a replacement.

Inductance: - 1.0 H
Maximum DC Resistance: -41 Ohms
Maximum DC Current: - 240mA

will the inductance be a problem  in the following attachment .

cheers

skal1
 

Attachments

  • 670 negative  bias.png
    670 negative bias.png
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Inductance as in how well it smooths. The engineering department probably calculate this in a sec. I suggest you simulate in following to see if ripple/voltage drop meets you requirements. You have not specified application.

http://www.duncanamps.com/psud2/
 
If its to replace L302, that drops 34-6.2 = 27.8V so if the original c-2327  was 56R, that's 0.5 A.  Even the original is iffy.  :eek:

If you just want to put it in series with R301 to get a little more smoothing for the -19V supply, the value is not critical but you probably don't need extra smoothing.  8)
 
that original choke in the 670  was rumored to run hot as a pistol and sometimes fail, probably due to the current,


that 1.5 Henries is  specified for the 200ma  DC current, so when they run it at a higher current, that inductance will probably drop, depending on how big the core is, and what the gap is,

they really wanted a stiff power supply to keep that bias point on the 6386 tubes rock solid, so the compressor does not thump with heavy bass notes, thus the high current thru the balance pot,

you could make that bias supply better by using a power trans with a lower AC sec volts, i think there is a discussion about this on the Drip site,

you could also try finding a Triad choke with the same specs as the Stancor if you wanted to run an original Fairchild circuit,

i could probably reverse that Stancor choke from the specs and size as to figure out the flux, wire size, you could get the same 28 volt DC voltage drop by using a choke done on a bigger core with wire a gauge or two bigger so that it will not break down like the Stancor,

this is from the Drip site link, notice  DCR = 85 Ohms which would mean 330ma for the 28 volt drop,>
http://www.dripelectronics.com/sitedocs/670_BOM_POWER_TRANSFORMERS.pdf

L302 / bias choke :
Stancor C-2327 (original part)
Class “A” insulating materials
and will withstand operation up to a limit of 105 ̊C., continuously
.
C-2327 A(105c) 1.5H 200mA 85.00 DCR 1500V
Mouser Part #:
802-C-2327
Manufacturer Part #:
C-2327
Manufacturer:
Stancor
Description:
Transformers 85 Ohms 1500V Filter Choke 1.5H
$11.83


Stancor Catalog>
http://www.clarisonus.com/Archives/Trans/Stancor61.pdf

data sheet on Stancor C-2327>

 

Attachments

  • Stancor-C2327.jpg
    Stancor-C2327.jpg
    165.8 KB
yes i stuck that on there in 1954, no wait....wasn't born yet,  umm, 1962?


that Stancor choke is probably a sq stack of 625 EI with 1500 turns of #31 or #32,

which is rated for 100ma but can run much higher,

larger wire will not have 85 ohms for that mean length turn times 1500,

400 gauss AC, 5000 gauss DC,  gap is probably .015 or .02 inches,

330 ma raises DC gauss to 8000,  so saturation is not a problem but wire size is,

wind it on a 75 EI and you can use larger wire and keep the same DCR,

Henries might go up if you need more turns to get DCR but that is OK,
 
I think that choke is just what Narma had handy. He dropped it in, it filtered, it dropped, it didn't burn-up, he left it.

IMHO a resistor would serve as good. The choke is so over-current that its inductance is down. 56 Ohms simple resistance into 1,000uFd is pretty good filtering. If not enuff, another 10,000uFd 15V is cheap today (wasn't back then!).
 
Narma was into overkill, don't think he would run a choke that hot,

probably would have used a resistor>

http://thehistoryofrecording.com/Schematics/Fairchild/Fairchild_660_mono_limiting_amplifier_schem.pdf


George Alexandervich?  he might have used that choke as a power resistor, they had so many transformers on that chassis anyway, the thought of adding another step down xfmr... probably no room left anyway,
 
CJ said:
i could probably reverse that Stancor choke from the specs and size as to figure out the flux, wire size, you could get the same 28 volt DC voltage drop by using a choke done on a bigger core with wire a gauge or two bigger so that it will not break down like the Stancor,

CJ , are you up to the challenge  of winding one ? if so i could fund you  i would buy 1 and send it to your location and you can do your take apart  thing , and maybe make a new one with a better spec  , i would by 2 if you are up for it and  if the price is around the same as a stancor.

cheers

skal
 
no need to take apart a choke, it is just one continuous coil on a bobbin,

just a matter of getting the DCR right so you get the voltage drop the same as the Stancor,

so we will spool up a coil on a 3/4" bobbin (for 75 EI) and see what happens,

inductance might be higher but that is a good thing,
 

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