On Thu, 10 Apr 2014, Jim Brown wrote:
On 4/10/2014 12:54 PM, Hisashi T Fujinaka wrote:
On Thu, 10 Apr 2014, Jim Brown wrote:
On 4/10/2014 10:40 AM, Hisashi T Fujinaka wrote:
The crowbar circuit trips on RF a lot. I've seen this on several
Astrons I own. Lots of ferrite on the leads helps.
What frequencies? When you say "lots of ferrites," did you wind turns
through them, or just clamp them on?
I've had issues on 40 and 15, and I think on 30. Definitely on 40,
though with a couple of different radios.
The power line I clamped on several (my supply of ferrite is just Radio
Shack and those aren't big enough) but I did use several turns on the
power supply leads near the power supply at first and then near the
radio as well when I had other issues.
I suggest that you download and study k9yc.com/RFI-Ham.pdf to understand how
ferrites work. A single turn (one pass of the wire through a ferrite core) is
next to useless at HF.
I'm not going to. I know the formula as well as you do and, like I said,
my only ferrite I have easy access to is from Radio Shack.
I know you think you have special knowledge, but it's still one turn
through ferrite of dubious origin which is NEXT to useless but not
useless.
I'm not sure what you're trying to determine here other than other ways
of trying to prove you know more than I do. All I was saying is that the
crowbar circuitry of Astrons is susceptible to RFI. I suppose I could
bypass it internally but the ferrites (oh, and some HV ceramic caps)
worked for me.
--
Hisashi T Fujinaka - htodd@twofifty.com
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
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