Phil, as usual, you have identified the problem(s) and given the solution,
all in one easy paragraph. For those that doubt Phil's recommendation of
the RF-3 sold at RF Parts, it costs under $25 and it works great. I
installed one of them in my 3CX3000 RF amplifier about a month ago and so
far there have been no problems, although I'm sure that I am pushing the
envelope as to how much current it can take, but that's another story.
Hopefully, Phil's recommendation will end this long and boring thread.
Bob Maser W6TR
----- Original Message -----
From: "Phil Clements" <philc@texascellnet.com>
To: <amps@contesting.com>
Sent: Friday, August 26, 2005 4:49 PM
Subject: Re: [Amps] plate choke
>
>> >> A single-layer choke of up to c. 60uH will exhibit no resonances below
>> >> approximately 35MHz, however, larger chokes will.
>
>> Which frequency?
>
> Life was much simpler when we only built 5-band amps years ago. With the
> addition of the 160, 60, 30, 17, and 12 meter bands, the choke building
> business got more complicated. Chokes that worked great on the five bands
> did not have enough L to do a proper job on 160 meters. More turns were
> required, which brought resonances into the spectrum below 30 mhz. With
> the
> additional bands, fewer places were available to "park" the resonances in
> a
> portion of the spectrum far enough away from any amateur band to avoid
> heating/smoke/fire. The folks that make the choke that RF Parts sells and
> Ameritron uses in their products produced a good compromise that avoids
> having to use two chokes to cover the 10 HF bands. This choke is c. 200
> uh,
> and the resonances are parked c. 11.5 mhz and 34 mhz. This varies slightly
> with each installation and chassis position. It is reasonably priced. I
> keep
> a stock here, and have used this choke on several projects with great
> success. It can be easily duplicated if desired. Please do not use Teflon
> rod as a poisonous gas is emitted when ignited.
>
> Before this choke was available, I went through several trial and error
> scenarios; some ending in disaster. Utilizing this product has been 100%
> successful for me in several projects over the years. Just something I
> don't
> have to worry about when lashing up a new amp.
>
> (((73)))
> Phil Clements, K5PC
>
>
>
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|