On Tue, 31 Mar 98 10:28:26 -0800 Rich Measures <email@example.com> writes:
>>On Mon, 30 Mar 1998 17:10:39 -0700 John Lyles <firstname.lastname@example.org> writes:
>>C'mon now John....what do you think the commercial companies used
>>days of old?
>Amen, Carl. Dipmeters are still good for finding resonances, and they
>always will be. A dipmeter showed me the falacy of using gapped
>sections on the same form.
I went nuts trying to test the Ameritron choke with the old '59
Rich...enough highs and lows to make a stock analyst wet his undies.
But the darn thing seems to work ...after a few changes by Ameritron.....
and it would sure be nice to see THAT one tested on a HP-4193.
>>A 1/2" diameter is ideal for 80-10M and maybe even 160M. The
>>choke is only 50uh but the first series resonance is around 45MHz. I
>>not tried extending that form factor to 100 + uh but it might bear
>As expected, the resonance moves down into the HF region, so you gotta
>careful on which frequency you park it.
Yep...but you dont know until you try it. BTW, parking is for horny
teenagers, not us old farts.
>>Also back in the 80's there was a HRM article mentioning the use of a
>>ferrite rod inside a choke form...the reference was a 5KW commercial
>>application with no series resonances 2-30MHz. Later on B&W used
>>concept on their BBC-5K choke.
>Two potential problems is that ferrite can saturate and ferrite is a
I used the recommended R61-50-400 rod at only 1000W BUT also used
Delrin...that may be my problem. Kinda forgot about the ferite concept
until this discussion.
I opened a B&W BBC-5K years ago and they use multiple flat ferrite bars
and wrap with #14 Teflon insulated wire. I built several 3CX3000A7
1.8-30MHz amps using that choke and they worked fine. Just my homebrew
that smoked and since I became a B&W distributor back then I took the
easy way out !
BTW, the BBC-5K has been out of production about 5 years now....a nice
job opportunity for someone.
73 Carl KM1H
>R. L. Measures, 805-386-3734, AG6K
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