[TowerTalk] Shunt Feed Woes

[jimlux]

On 12/8/19 1:35 PM, Jim Brown wrote:
> The company's definition of success is that the unit doesn't fail 
> destructively -- that is, overheat and destroy itself. Perfect as a 
> business philosophy if the only test instrument your customer owns is an 
> SWR meter and maybe an antenna analyzer. The problem is that their 
> primary effect is to transfer dollars from the buyer to the seller.
> 
> I don't sell anything, and have no relationships with anyone who does. 
> My own designs, based on extensive research and lab work and published 
> for free, are vastly superior to any commercial products I know of and 
> easy to build.
> 


But, I would venture to say, would be more expensive if you built them 
and tried to sell them.

There are several of these kinds of products (baluns, transformers, 
filters) that I've looked at starting a side business of manufacturing 
and selling.  And I've come to the conclusion that nobody would pay the 
price I'd need to set, especially given the very small volumes involved.

A typical rule of thumb is that the retail price is 5 to 10 times the 
cost of the parts involved (the BoM cost) - that covers the labor to 
assemble, various and sundry expenses, and the markups through the 
distribution and retail chain.

http://k9yc.com/2018Cookbook.pdf

Let's take a simple example, a 160-10M choke which is 14 turns on one 
core and 17 turns on another core, using RG400.
Jim has helpfully provided a cost estimate of $24 and $26 for each of 
these at: http://k9yc.com/Chokes-2r4inRG400.png



What goes into this:
Coax with connectors
The cores
A structure (you don't want a box, because you need cooling)
Fasteners to hold the connectors on the structure.

cores: 2631803802 which is digikey part # 1934-1100-ND and runs $4.90 
each in qty 50.
coax with connectors: Something like RG-400 that is 5 feet long is $67 
from Pasternak with a PL-259 (UHF) on each end. The price is $6/ft plus 
the connectors and labor to assemble it.

Sure, if you had volume, and tooling, you could build your own cables. 
But that's just trading off parts cost with labor cost. In small 
volumes, it's going to be hard to find someone to install those 
connectors, and if you've got enough volume, the person is going to cost 
you around $25-30/hr (with taxes, unemployment, etc).

But in any case, you're looking at a BoM cost of $50-100 by the time you 
include all the bits and pieces.

And that's a retail price of $500.   How many hams are going to buy a 
$500 RF choke/balun? The most expensive one I found at HRO's catalog was 
$140.

Sure, the K9YC design will have better performance, etc.
But nobody will buy it as a finished product.





> 73, Jim K9YC
> 
> On 12/8/2019 12:50 PM, Doug Renwick wrote:
>> I use a quite a number of Balun Design baluns and can find no fault with
>> them keeping in mind that I have not evaluated them on the bench.
>> A friend of mine replaced a troublesome Maple Leaf design balun on his 
>> OCD
>> dipole with a Balun Design unit and is pleased with the result.
> 
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