[TowerTalk] Balun Recommendation

[K8RI]

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.


73

Roger (K8RI)
>
> 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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