Date: Fri, 17 Feb 2017 07:41:09 -0700
From: Chris <EZRhino@fastmovers.biz>
To: "towertalk@contesting.com reflector" <TOWERTALK@contesting.com>
Subject: Re: [TowerTalk] What am I missing....balun
Is there any chance this is an April Fool's joke?
Chris
On Feb 17, 2017, at 6:40 AM, ve4xt@mymts.net wrote:
> I've been trying to divine a defence for this box, but can't.
>
> If I read K9YC's choke cookbook correctly, there's no way this could achieve
> the level of broadband choking claimed. Moreover, not only is there no need
> to enclose such a device in so expensive an enclosure, it would compromise
> power handling. And if you did, how do you mount it at the only place it does
> any good?
>
> When it appears the best-performing choke in Jim's cookbook is nothing more
> than a frequency-specific number of turns of coax through, at most, $50 in
> ferrite cores, with no bulky enclosure, I just can't see why anyone would pay
> $900 for this.
>
> Also, if the photo is akin to an "exemplar" piece of furniture, and the box
> is built to custom specifications, then the quoted specifications are
> meaningless anyway.
>
> BTW, isn't the attenuation noted (called return loss) the only way any choke
> actually chokes?
>
> I think Array Solutions has some 'splainin to do!
>
> Then again, PT Barnum has never been proved wrong.
>
> 73, kelly, ve4xt
>
#### jay at array solutions posted a note on the AMP reflector on tower talk.
The unit is optimized for the 11m folks like I thought. Hence the 26.980
mhz marker on the screen. Kelly, return loss is just another way of
expressing SWR .
The higher the return loss, the lower the swr. You sweep the unit and note the
return loss. IE: what is the swr with the unit terminated with a 50 ohm
dummy load. You would expect it to be dead flat or close to it, on the freqs
of interest.
Same deal with LP and HP filters, or say an amplifier on bypass mode. At
the telco I worked at, we used return loss measurements exclusively, and
nothing was expressed in swr ratios.
### That is RG-393 coax.. Double silver plated braids and silver plated
stranded center conductor. Teflon dielectric and FEP-9 outer jacket. That
stuff runs aprx $7.00 per foot these days. For 20-6m, type 43 is typ used
. If you look at the K9YC cookbook, he states either 31 or 43 used on
20-6m. The price tag of the unit was not what I was on about, but the stated
1.8 to 60 mhz freq range on their site.
## The fancy test gear is what measures the actual choke Z and RS of the
choke. Knowing that, then you can calculate the attenuation in db of any
shield current. I think you are confusing shield current attenuation in
db...with return loss attenuation, which is also in db.
Jim VE7RF
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