I came up with that mod when I was tuning a bent sloper on 160 that had a
weird impedance that caused so much current through the stock caps that they
started smoking with 100 Watts. You can tell when the little disk caps are
overheating...you set the tuner for a good SWR, then in key down, it starts
to drift upwards. Then comes the smoke! In the pictures on my website, if
you look really carefully, you can see where the smoke discolored the
chassis right behind the bandswitch. With the Russian doorknobs, I could
run 1.5 kW into that sloper in a 160 contest and it was rock solid.
Ron Castro
N6IE
www.N6IE.com
Member:
ARRL
Redwood Empire DX Assn.
Northern California Contest Club
Northern California DX Foundation
Society of Broadcast Engineers
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim Allen
Sent: February 17, 2016 5:54 PM
To: Clayton Brantley; Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Ten-Tec 229A Tuner Value
Isn't it true that heating means less than optimum efficiency...... all that
power heating the tuner instead of putting fire in the wire?
73 de W6OGC Jim Allen
Sent from my iPad
> On Feb 17, 2016, at 19:25, Clayton Brantley via TenTec
<tentec@contesting.com> wrote:
>
> Jim: The 229/238 will run at legal limit for quite a while on almost
> all bands. The problemrears it's head on 160 meters where you might run
into some weird mis-matches. At lowpower it seems to work OK but at hight
power, the .01 disc caps just cannot handle the current. I found some
Russian caps for around $30 to replace the stock caps. Now my229A remains
quite cool. I believe this thing will tune the proverbial wet noodle in a
copperbox! I have had several match boxes over the years and I will not
part with this one.
> If you do not use 160 meters, then this mod is un-needed.
>
> 73 Clayton N4EV
>
> From: Jim Brown <k9yc@audiosystemsgroup.com>
> To: tentec@contesting.com
> Sent: Wednesday, February 17, 2016 6:14 PM
> Subject: Re: [TenTec] Ten-Tec 229A Tuner Value
>
>> On Wed,2/17/2016 9:46 AM, Gary H. Harmon, Jr. wrote:
>> Is there a written mod somewhere about replacing the caps and which ones?
>
> I've seen recommendations to replace all of the fixed caps with
> doorknobs. That's a bit of overkill. :)
>
> I ran my Ten Tec 229 and 238 tuners at legal limit, and there were
> several caps that eventually blew. I don't remember exactly which
> ones, but I do remember one that was at the rear of the bandswitch.
> I'm using surplus HV caps with relatively low temperature coefficients
> (N750 or N330), low ESR (equiv series resistance) and high current
> handling. The caps I use came from browsing the aisles at this surplus
> house. It's unlikely that you can do any good online.
>
> http://www.halted.com/
>
> 73, Jim K9YC
>
>
>
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