[TowerTalk] antenna choices for K4XS

Sun Apr 19 23:16:42 EDT 2015

Best choice for what? The best choice to choke or not to choke, or the 
best choke?

My thoughts?

I want an antenna with a balanced pattern and with a more or less 
conventional feed system whether it requires a choke or not. Reasonable 
gain and f/b.  to me f/b is important as I have major signals off the 
back no matter the direction I use for DX except South America.

I'd probably use a choke (based on K9YC's tutorial, giving on the order 
of 4,000 to 5000 ohms isolation) anyway because, even antennas with a 
balanced design tend to become unbalanced in the real world for a number 
of reasons.  A properly designed choke also reduces feedline "pick up" 
and reduces noise.  Jim's designs have made a great difference here even 
with simple antennas.  His tutorial also changed what I thought I wanted 
and/or needed.

As to performance, on here we all have opinions as do I.  But almost any 
antenna "works".  I've made some impressive mobile contacts. Impressive 
at least to me and when we talk mobile we are looking at some real 
negative gains in reference to verticals or dipoles.

When some one reports, "man!" you sure have a strong signal!  It's 
difficult to give credit to anomalous band conditions when your new, 
$2000 pile of educated Aluminum was just installed.  Yet I had a nearby 
ham (now a SK) call on the phone looking for a way to get his new, 
large, very heavy, and expensive pile of educated Aluminum to do as 
advertized.  It just wasn't performing as well as his old inexpensive 
antenna.  He expected to see/hear some real changes. Real he had, but 
not the ones he wanted.  Sounds more like "Hope and change<:-))

No study is perfect and even a PHD thesis does not address all the 
problems, so under the conditions I think K7LXC's study is quite 
thorough even with the short comings that have been pointed out. It is 
after all, the most comprehensive comparison available. Anyone who 
wants, has the time, and money is welcome to do a new study, or send him 
some relative updates that can be replicated.

"I think" I know what I want in and from an antenna.  What I know has 
changed a number of times to the point where I say "I think I know" what 
I want.

In nearly 54 years as a ham, I've seen many antenna and equipment 
claims. Enough that I'm usually skeptical of claims even from old and 
well established firms.

I'm not talking about just antennas.  Look at today's top end rigs (one 
of my pet peeves as many already know).  I have no reason to doubt those 
really impressive numbers for the receiver sections. Even if those 
numbers are conservative, do they mean anything useful?  Many receiver 
dynamic range, selectivity and IM numbers are well past the point of 
relevance, or usefulness.  They are a valid number but only good for 
bragging rights

What good does an HF sensitivity and noise figure do for me when the 
noise floor on those bands is 10 to 20 times that figure even when I 
ignore local noise?  What good do super narrow, steep sided filters do 
for me when a station 10 KHz up (or down) is 20 KHz wide or trying to 
get the legal limit out of 4 811s? (even get what the amp builder claims 
the amp will do) What good do all these outstanding (and useless), but 
impressive numbers do when most of the transmitters on the band have an 
IM3 of 30 to 35 db?

IF and that's a mighty big if all new transmitters went to an IM3 of -45 
to -50 db today, how many years would it take for the bands to show a 
noticeable improvement to where some of these fantastic receiver numbers 
would become relevant?

Some, like sensitivity and noise figure, never will because of the 
slowly, ever increasing noise floor, but selectivity and dynamic range 
will.  Actually, dynamic range is the one number that can make a 
difference under certain conditions, today.       I have, on occasion 
moved the antenna off the desired heading to null QRM off the back, or 
in a side lobe.

One other condition:  Today's hams need to learn how to properly set up 
their rigs.  Then master how to tune and use amplifiers!

73

Roger (K8RI)

On 4/19/2015 8:37 PM, Bry Carling wrote:
> So, what IS the best choice?
>
> Best regards - Brian Carling
> AF4K Crystals Co.
> 117 Sterling Pine St.
> Sanford, FL 32773
>
> Tel: +USA 321-262-5471
>
>
>
>
>> On Apr 19, 2015, at 7:18 PM, Pete Michaelis - N8TR <pete.n8tr at gmail.com> wrote:
>>
>> I just downloaded a Mosley Pro 67-C Manual from:
>> http://www.radiomanual.info/schemi/ACC_antenna/Mosley_PRO-67-C-3_user.pdf
>>
>> Apparently they now do recommend an RF choke.  It says "You want to insert
>> a R. F. Choke into the Coax line to eliminate any RF on the Coax line".  They
>> do go on to suggest a 10 turn choke made from coax which often is not the best
>> choice.
>>
>> 73 Pete - N8TR _______________________________________________
>>
>>
>>
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-- 

73

Roger (K8RI)

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