[Boatanchors] Grounded Grid filament choke spec's

[Carl]

I hope that my comment was not taken as an endorsement of the FC-30 for 160M 
since as you say it is not adequate.

The most foolproof choke is the 7 1/2" x 1/2" 33 Mix ferrite as I mentioned 
yesterday and will be fine with either #10 or 12 wire so it will work with 2 
x 3-500Z's, a 4-1000A/3-1000Z, or anything similar in total filament 
current.

Its been decades since I did a VNA plot or inductance measurement on them so 
I cant quote absolutes but they were very good.

I have those rods and wire available for $27.50 shipped. Specify wire size 
wanted. This is less than Amidon charges for just the rod with shipping.

Radiokit is coming back to life now that Ive time again. It will be mostly 
amp and boatanchor related.

Carl
KM1H




----- Original Message ----- 
From: "Kenneth D. Grimm, K4XL" <grimm at sbc.edu>
To: "Greg Mijal" <bluebirdtele at embarqmail.com>
Cc: <boatanchors at mailman.qth.net>
Sent: Friday, June 05, 2009 10:08 AM
Subject: Re: [Boatanchors] Grounded Grid filament choke spec's


> Hi Greg,
>
> Although you have received a couple of responses saying that the FC 30
> will be OK for 160 mx, I feel that I should point out that B&W rate the
> FC 30 for 3.5 - 30 MHz.  Also, I have heard others say that the FX 30
> won't work on 160.  Whether their comments were based on trial and error
> or on simply accepting the manufacturer's ratings as gospel, I can't say.
>
> 73,
>
> Ken - K4XL
>
> Greg Mijal wrote:
>> Hi:
>> A couple of months ago the group discussed using filament chokes in 
>> grounded grid amplifiers.  Someone mentioned that if you were planning to 
>> use the amp on 160m a larger filament choke was required.
>> So what's up with that? What's the magic number of uh's needed to 
>> decouple a 160m driving signal?
>> I measured a B&W FC 30 filament choke and it measured in the 7 - 10 uh 
>> range for each wire. Am I ok using the FC 30 as is on 160m?
>> Tnx
>> Greg
>> WA7LYO
>> Kinston NC
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>
> -- 
> Ken K4XL
> k4xl at arrl.net
>
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