[Amps] turns = henries question

[Gary Smith]

Thanks for the reply

The plot sickens...

In the schematic it calls for a 60 uH choke. The measurements I gave 
were from a digital caliper and I measured the dimensions with that 
same caliper.

I had an arc which jumped from the plate blocking cap to the choke 
and blew out the cap and though it did not exactly blow out the 
choke, it left a bit of copper ball on one of the windings and made 
an amplifier version of Blackened red fish on the coil.

Although all the turns are still intact and continuity is intact, I'm 
hesitant to use it as some of the enamel is missing and if nothing 
else, the carbon is not a good insulator.

I discovered the schematic is not exactly correct for other component 
placement & values, I'm not surprised the plate choke values are 
different also. 

This choke is for a pair of 3CX800A7s at 2.4KV

The measurements I made a'la wire size & turns/inch are indeed 
correct.

Idears?

Thanks,

Gary


> Hi Gary,
> 
> The coil as you've described should be about 80 uH.
> 
> A 3" winding, other dimensions remaining constant, will provide 60 uH.
> 
> Calculations performed on an American Hydromath Calculaide Frequency Computer (circular slide format), 1955 vintage.
> 
> FYI: At 45 TPI, the wire is likely #24 enameled.
> 
> 73 & Good afternoon,
>    Marv WC6W 
> 
> http://wc6w.50webs.com/
> 
> 
> --- On Sat, 2/21/09, Gary Smith <Gary at doctorgary.net> wrote:
> 
> > From: Gary Smith <Gary at doctorgary.net>
> > Subject: [Amps] turns = henries question
> > To: Amps at contesting.com
> > Date: Saturday, February 21, 2009, 11:21 AM
> > Hi,
> > 
> > For you math whizzes out there (math is not my strong
> > point)...
> > 
> > I need 60uH for a plate choke. 
> > 
> > The existing coil apparently uses 23 guage wire and the
> > coil form is 
> > .676" OD. There are 45 turns per inch and the length
> > of the windings 
> > on the coil form is 4.052" long.
> > 
> > Accdording to wikipedia
> > 
> > http://en.wikipedia.org/wiki/American_wire_gauge
> > 
> > My wire measures .022" so acording to the chart, I
> > call that 23 
> > gauge. Radio shack has enameled wire but the closest guage
> > is 22 
> > Gauge and that measures .025" which also jives with
> > the chart.
> > 
> > I don't know how many turns of the 23 guage on this
> > coil form will 
> > give me 60uH. Can anyone help me out on this?
> > 
> > Thanks,
> > 
> > Gary
> > KA1J
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> 
> 
>       
>