[Amps] 160M PI network Toroidal Coil

[Carl]

I recommend a real HV fuse or a homebrew version. I DID NOT suggest using a 
bare wire.
A glitch resistor is always a good idea and it should be mounted close to 
the base of the plate choke and bypassed at the PS end.

Carl
KM1H


----- Original Message ----- 
From: "George" <at6c at bellsouth.net>
To: <amps at contesting.com>
Sent: Sunday, October 06, 2013 8:49 AM
Subject: Re: [Amps] 160M PI network Toroidal Coil


Hi Carl,
What size wire would you recommend for a 1A supply?  If there is a
choice of where to insert the wire would you use it in the RF
compartment or near the B+ supply?  Would you recommend a glitch
resistor?  If so what size, value and type (carbon, film...)? Thanks
73, George
W2GS

On 10/5/2013 6:38 PM, Carl wrote:
> A sustained arc in a small glass fuse improperly used at 10 times or more 
> its rating is far from a rare occurance.
> It gets downright dangerous when the glass breaks and the small arc 
> becomes a monster plasma arc searching for paths to ground.
>
> Using a small wire as a HV fuse can also create a similar problem.
>
> Carl
> KM1H
>
>
> ----- Original Message ----- From: "Bryan Swadener" <bswadener at yahoo.com>
> To: <amps at contesting.com>
> Sent: Saturday, October 05, 2013 6:41 PM
> Subject: Re: [Amps] 160M PI network Toroidal Coil
>
>
> I might as well add my input...
>
> My GS35b 160m monobander will use about 15uH fixed
> and 16uH adjustable, to drive ~ 25 to 500 ohms.
> The fixed inductor is 20T 10 AWG 19-strand silver-
> plated copper wire (w/ PTFE insulation) on a Micrometals
> T400-2D core. Core and wire losses should be naught.
> I found two cores and the wire on ebay for a good price.
>
> I used my spreadsheet calculator to determine the maximum
> wire diameter, number of turns and length of wire needed. YMMV.
>
> Mike, that's interesting about the fuse. At HV with
> a 250V fuse, I would've expected a sustained arc.
>
> vy 73,
> Bryan WA7PRC
>
> ------------------------------
>
> Date: Sat, 5 Oct 2013 13:10:21 -0500
> From: Mike WØBTU
> To: amps at contesting.com
> Subject: Re: [Amps] 160M PI network Toroidal Coil
>
> When I converted my SB-200 to a single-band 160m amp, I followed the
> directions (more or less) at
> http://pa0fri.home.xs4all.nl/Lineairs/SB200/sb200eng.htm#DESIGN . The
> toroid was a single T-200-2 core with between 11t and 14t of #14 stranded
> PTFE insulated wire, IIRC. The details are on that site. I got almost 800w
> out on 160 CW.
>
> I also used a large (>1600 pf) external variable loading cap to the output
> with a UHF tee connector and a short length of RG-58C/U.
>
> Some photos except for the toroid (on the bottom) and the added plate 
> choke
> are here:
> http://www.w0btu.com/files/misc/SB-200/ . The extra filament choke and the
> PA0FRI input mods are clearly visible in the first photo.
>
> While you're at it, add the fuse and series 10 ohm 10w resistor to the HV
> line. I used an ordinary 250 volt AGC 1 amp fuse. When I first replaced 
> the
> tubes, it blew a couple of times with nothing more than a silent blue 
> flash.
>
> 73, Mike
> http://www.w0btu.com/
>
>
> ------------------------------
>
> Date: Sat, 05 Oct 2013 11:44:02 -0700
> From: Paul Baldock
> To: amps at contesting.com
> Subject: Re: [Amps] 160M PI network Toroidal Coil
>
> Thanks to every one on their suggestions. It seems that multiple
> T200-2 cores are the most common.
>
> - Paul
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