On 4/15/2012 11:08 PM, Jim Lux wrote:
> On 4/15/12 5:47 PM, Jim Brown wrote:
>> On 4/15/2012 1:48 PM, Frank wrote:
>>> Good point. Sounds like a good reason to build your own.
>> One of the points I've tried to make in my writing is that we can build
>> MUCH MUCH better ferrite chokes than we can buy at any price, if we
>> understand how they work. The ordinary stuff (in the $30-50 range) I've
>> seen is essentially useless, and while the expensive stuff ($120 and up)
>> is far less likely to burn up. it isn't very effective either.
> which makes me wonder, why is that..
> There's a labor cost (which can be substantial.. something the "you can
> build it yourself cheaper" doesn't always contemplate).
> but it seems that I could build, for instance, chokes with decent coax
> jumpers, some number of 2.4" mix 31 cores, and an enclosure of some sort
> for around $20-30 in parts.
Depending on where you get them and how many you buy the main cost is
the cores. Currently "I think" they are running between $5 and $7 each.
So a 6 core, all band choke that covers 160, 75, and 40 could run $30 to
$42 for the cores and about $6 for a pair of PL-259s. IIRC it takes
about 6 feet of Davis BuryFlex for 6 turns. It takes about 20 minutes
to wind a choke and install the connectors.
You can plan on these things really working. I had RF coming back into
the shack on 75 to the point I couldn't run full power. All the LED
were lit to full brilliance at about 1KW out. I added a choke at the
feed point and one where the coax came back to the tower. Absolutely no
RF coming back into the shack now.
> Based on my experience in the "low volume specialty equipment" business
> for the entertainment industry, that would turn into a list price of
> around $200-300, normally sold discounted at maybe 20-30% off that.
> Maybe that's why.. hams won't pay $250 for a decent choke.
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