Topband: Length of Beverages

[Carl]

There is really nothing new to explain. It has been established since the 
mid 1920's that the Beverage is a slow wave antenna, ie: it has a velocity 
factor, and at an electrical 50% VF it will reverse direction.

It doesnt take much effort or math to compute the electrical length 
shortening of a Slinky and I believe I stated that mine was around 60% on 
this reflector in the late 90's and I was supplying Slinkys to others in the 
US and international. This was also picked up by ON4UN who published the 
Slinky Beverage in one of the earlier revisions of his book with incomplete 
data to easily reproduce.

Using a 1590 BC station directly to the rear I determined the proper 
termination resistance to be 1200 Ohms for the final version. This was 
around 1987-88 and years before I even knew about any reflectors and 
discussions were only on 160 SSB just above the DX window when the band was 
dead. K1ZM gets the credit for planting the idea during one of those chats 
and it didnt take me long to work out the details. Those 1987-88 experiments 
took many forms and the number of Slinkys used and running 100-300'. Other 
lengths required different terminations and transformers. After a certain 
person started in with belittling comments I stopped posting and just shared 
later data via direct emails or phone calls.

Doing a Google on "KM1H Slinky Beverage" will give loads of hits and also 
refreshed my memory...disregard the 18 month useful life...that was after 
they were no longer cadmium plated.

Carl
KM1H



----- Original Message ----- 
From: "Mike Waters" <mikewate at gmail.com>
To: "topband" <topband at contesting.com>
Sent: Monday, July 28, 2014 12:42 PM
Subject: Re: Topband: Length of Beverages


> Hi Jim,
>
> As we move the turns closer, we increase the velocity factor too much. At
> some point, the Slinky will receive off the opposite (feed) end. Tom
> explains it at
> www.w8ji.com/slinky_and_loaded_beverages.htm .
>
> And I just found this, where K5UO seems to say that his Slinky was about 
> 12
> turns per foot.
> lists.contesting.com/_towertalk/2006-12/msg00510.html
>
> 73, Mike
> www.w0btu.com
>
>
>
> Mike, what do you mean when you say "fires backwards".
>>
>>
>>
>> On 7/28/2014 8:59 AM, Mike Waters wrote:
>>
>>> Carl,
>>>
>>> On Sun, Jul 27, 2014 at 6:53 PM, Carl <km1h at jeremy.mv.com> wrote:
>>>
>>>  I knew that answer 20 years ago Mike. Perhaps someone has a large 
>>> Slinky,
>>>> can count the turns and then give it back to his grandson (-:
>>>>
>>>>  Ok. I think the thing to do is just experiment with the length/pitch.
>>> Stretch it out along the rope, past the point where it fires backwards
>>> (and
>>> then some), maybe.
>>>
>> ...
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