Art Trampler wrote:
> Roger,
>
> I was having trouble with the choke overheating on 40 meters because it had
> been wound with a lot of the windings at five o'clock instead of having the
> evenly spaced.
Other than the bees nesting inside the matching network I've had no
problems even running the legal limit, but the duty cycle has been low.
> Anyway, that is fixed now, but I considered as a work around
> getting a higher power choke balun and 4:1 unun from Balun Designs.
I plan on using a higher powered 4:1 balun as I plan on higher power, or
rather a much higher duty cycle plus higher power on 6-meters. I have
lots of #31 mix cores, or will within a few days, but I understand the
#43 mix is better for 50 MHz. I'll probably use 4 cores instead of 2
and Davis BuryFlex instead of the small coax for the current balun. For
the 4:1 I'll probably also use 4 cores and go to Teflon insulated #10
wire, but those are just thoughts at present.
> Granted
> it would have been pricey, but it would have done the job and might meet
> your needs.
>
>
I have basically every thing I need, I just need to figure out what to
use. That and I'll probably need to house the matching network in a
larger box and use a capacitor that will handle more current.
73
Roger (K8RI)
> Art, KØRO
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Roger (K8RI)
> Sent: Sunday, April 04, 2010 8:52 PM
> To: TowerTalk
> Subject: [TowerTalk] HyGain AV640 Toroid core mix, or Beefing up an AV640
>
>
> Any one have any idea as to the core mix used in the AV640 baluns? It
> has two in the matching network. One is a current balun and the other a
> 4:1. Then they use a series cap to tune out the reactance of the
> slightly long antenna.
> The is designed for all ham bands from 40 through 6 meters. Power is
> limited to 1.5KW PEP 40 through 10 and only 200 or 300 watts on six.
>
> I'm assuming that either the core material and/or the series cap is what
> limits the power on six.
> As the power is also limited for RTTY/Digitl 40-10 I'd assume it needs
> some larger (or more cores) to handle the heat in the 4:1 balun and
> probably the current balun as well.
>
> I'd like to beef this thing up so it'll take 1.5KW for any mode,
> although I don't know of any mix that will let me do it over the entire
> range of 40 through 6 meters. I'd also feel a bit more comfortable
> running it the legal limit contest style although it's a back-up antenna.
>
> 73
>
> Roger (K8RI)
>
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