[Top] [All Lists]

[AMPS] don't choke on this

To: <>
Subject: [AMPS] don't choke on this
From: (km1h @
Date: Tue, 31 Mar 1998 13:59:17 EST
On Tue, 31 Mar 98 10:28:26 -0800 Rich Measures <> writes:
>>On Mon, 30 Mar 1998 17:10:39 -0700 John Lyles <> writes:

>>C'mon now John....what do you think the commercial companies used 
>back in
>>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   
>FAQ on WWW:     
>Administrative requests:

You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at
Or call Juno at (800) 654-JUNO [654-5866]

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>