[Amps] Why do tubes cost so much?

Tue Aug 31 05:17:07 PDT 2010

Well, no, I don't play with cars. I was always an electronics guy first and 
foremost, from an early age. I didn't even get a driver license until I was 
18. LOL  If it didn't directly contribute to ham radio, I wasn't interested.

And it's true that my assumption regarding 6-meter yagis is low-end 
(50.0-50.5 MHz) weak-signal operation. Why on earth would you want a yagi 
antenna at 53 MHz? I mean, what's even there? Repeaters? (Don't get me 
started... ) If you really have a need for directable weak-signal repeater 
work at the high end of the band, model an optimized, high-efficiency yagi 
design for that frequency that can be mounted vertically polarized (i.e., 
you design that into the model).

As for the A50-5S, you can make it much better without extending the boom 
just by removing one of the excess parasitic elements and remodeling. It 
will have slightly more gain and a much better pattern. Same is true for 
their 6-element yagi (A50-6S). Remove one of the directors, remodel as a 
5-el and optimize for best trade-off of pattern vs. gain. It too will be a 
much better antenna with fewer parasitic elements. Will it be as 
broad-banded? I have no idea, I've never even attempted to model a yagi for 
6 meters above 50.5 MHz. I have zero interest in anything that's currently 
up there. Now, if they opened up the band plan a little so that the vast 
majority of 6m users weren't all jammed together into the bottom 300 kHz or 
so...

Anyway, I suppose we should nip this VHF thread in the bud, as it's 
off-topic. I shouldn't have brought it up, but it seemed like an obvious 
example of the point I was trying to make. Maybe I was wrong. :-)  Mea 
culpa.

Bill W5WVO

--------------------------------------------------
From: "Carl" <km1h at jeremy.mv.com>
Sent: Monday, August 30, 2010 19:07
To: "Bill VanAlstyne W5WVO" <w5wvo at cybermesa.net>; "[Amps]" 
<amps at contesting.com>
Subject: Re: [Amps] Why do tubes cost so much?

> I guess you dont play around with vintage vehicles Bill. Reproducing old 
> parts is a huge and profitable business if the quality is there. Some have 
> the blessings of the Big 3.
>
> And it doesnt have to be that old either, anything from around 1971 and 
> earlier is fair game.
>
> Id almost think a 4-1000A could be built at home by a very talented 
> industrial modelmaker, not toy models.
>
> As far as the current CC 5el for 6M, that was PC designed and is pretty 
> decent considering the wide bandwidth it has to cover. A PC program cant 
> do much better on a 12' boom except optimize the F/R at the low end. 
> Anybody can run off a decent yagi for the low end CW/SSB operators.
>
> Carl
> KM1H
>
>
> ------ Original Message ----- 
> From: "Bill VanAlstyne W5WVO" <w5wvo at cybermesa.net>
> To: "Carl" <km1h at jeremy.mv.com>; "[Amps]" <amps at contesting.com>
> Sent: Monday, August 30, 2010 1:33 PM
> Subject: Re: [Amps] Why do tubes cost so much?
>
>
>> This is an interesting thread in terms of manufacturing and marketing 
>> "philosophy" (if you will). When you're looking at a tube that has been 
>> around for a while, you're basically looking at a post-maturity product. 
>> That doesn't mean that the demand for the product is lessening, just that 
>> it has stopped increasing and the product has stopped evolving to more 
>> efficiently meet increasing demand. You reach a "good enough" balance 
>> point where you're going to be meeting current and future demand and are 
>> making your margin. Why try to change anything when all your R&D 
>> resources are 100% absorbed working on future products?
>>
>> Another case in point is the family of Cushcraft VHF yagi antennas, which 
>> have been marketed essentially untouched for decades. The designs go way 
>> back before computer modeling, and they basically suck (most notably the 
>> 12-foot 5-element 6m yagi). Many people, including myself, have 
>> redesigned them using computer modeling and vastly improved their 
>> performance. Cushcraft could obviously do the same thing. But do they? 
>> No. They're in the post-maturity phase of these products, and it is 
>> simply not worthwhile for them to put one more DIME into them for R&D.
>>
>> I think there may be some axioms at work here.
>>
>> Axiom #1:
>> You can make more money selling something new than selling something old.
>>
>> Axiom #2:
>> If you make something old better with new technology, to the marketplace 
>> it's not something new, it's still something old. See Axiom #1.
>>
>> Axiom #3:
>> If you ARE making money selling something old that really isn't very 
>> good, but it is absorbing zero dollars in engineering overhead, just keep 
>> selling it, and don't put another DIME into it to make it better. See 
>> Axiom #2.
>>
>> Bill W5WVO
>>
>>
>> --------------------------------------------------
>> From: "Carl" <km1h at jeremy.mv.com>
>> Sent: Monday, August 30, 2010 13:04
>> To: "Jim Tonne" <tonne at comcast.net>; <amps at contesting.com>
>> Subject: Re: [Amps] Why do tubes cost so much?
>>
>>> I read somewhere (years ago so dont quote me) that tubes with extremely
>>> close grids such as the 3CX800 and 1500 have yields around 20%. You 
>>> would
>>> think that after all these years companies would have better technology
>>> available to assemble.
>>>
>>> Setup times should be controlled also, I just suspect that Eimac doesnt 
>>> care
>>> since they still have the bulk of the market that will pay whatever it
>>> costs.
>>>
>>> Carl
>>> KM1H
>>>
>>>
>>> ----- Original Message ----- 
>>> From: "Jim Tonne" <tonne at comcast.net>
>>> To: "Frederick Mott" <fredmott at zoominternet.net>; 
>>> <dezrat1242 at yahoo.com>;
>>> <amps at contesting.com>
>>> Sent: Sunday, August 29, 2010 9:40 PM
>>> Subject: Re: [Amps] Why do tubes cost so much?
>>>
>>>
>>>>
>>>> I think that Bill and Fred have summarized things
>>>> nicely.
>>>>
>>>> But I also suspect that the "tiny" tubes like a 6BA6
>>>> are assembled in a relatively (if not entirely) automated
>>>> operation.  And I chose the 6BA6 because of how the
>>>> first grid is formed, with that nonuniform winding.
>>>>
>>>> The "big" tubes - those with 100 kW or more of plate
>>>> dissipation - offer the same challenges that the 1000
>>>> watt tubes do but are simply scaled up and are
>>>> larger in every respect and so probably relatively
>>>> easier to build.   The cost of materials in those huge
>>>> tubes is probably significant.   So is warranty cost.
>>>>
>>>> - JimT   W4ENE
>>>>
>>>>
>>>>> I have often wondered why big tubes cost so much.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
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>>>
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>>>
>>>
>>
>
>
> 