[Elecraft] [K3] Filter prices

[Eric Swartz - WA6HHQ, Elecraft]

Wow, I wish we could buy 8 pole filters in amateur radio volumes for a 
wholesale price 1-5$. Or even $30-$40! They just don't exist. (But let 
me know if you find some..)

Our filters -were- designed for their excellent IMD performance. Also, 
we have these filters tested for IMD and passband response during 
manufacture. Its always possible one can slip through, but not very often.

And the K3 -does- provide top of the line front end performance. Even if 
you subtract 5-7 dB from our verified lab test numbers at the ARRL and 
Sherwood you are in the top tier of all amateur rigs. Period. All of the 
reviewers (ARRL, Sherwood, Radcom etc) have praised the K3 for its top 
of the line performance.

Let's also remember that the IMD dynamic range numbers we are now 
testing for (95-100 dB+) push the limits of many test lab set ups. 
Without careful measurement technique and appropriate gear it is easy to 
confuse the IMD limits of the test set up equipment with the rig. I've 
personally tripped across that many times here in my lab and have helped 
others clean up their lab set ups. Also, there are several methods to 
test IMD dynamic range. (IMD product at MDS, at S5 etc.) With a 
non-linear device like a crystal filter, the level of test signal is 
critical for accurate comparisons. It does not act like a transistor 
amplifier does when subjected to signals at its upper limits. We've seen 
several folks (including ourselves) test at signal levels way above the 
max the filter will ever see and then incorrectly try to extrapolate 
back to IMD performance at expected use strong signal levels. Its easy 
to get widely varying and inconsistent results when testing that way.

But the bottom line is: How does a radio perform in actual use? I'll let 
our customers past and future postings speak for that. :-)

73, Eric   WA6HHQ
-----

Jerry T. Dowell wrote:
> The high prices of the roofing filters for the K3 and optional filters for
> other rigs reminds me of a little history.
> ..... Drake and others had switched to Japanese suppliers since
> they could get the filters for a little over $1 each, whereas his cost was
> over $2 each. Note that there were no middlemen. Drake was selling their
> filters for $40 or $50 each, I forget which. A tidy profit. Howard charged
> me $40 for that CW filter, by the way. Inflation since that time has been about a factor of 2.6, according to official US Government figures:
>
> Some of us would disagree with the official numbers, putting it closer to a
> factor of 10, 
>   
> Nevertheless, I find it especially disturbing having to pay these modern
> prices considering that the filters have apparently not been designed or
> chosen for good IMD performance or advantageous group delay characteristics.
> Also, some filters are reputed to have been defective. Of course, the
> filters may not be totally to blame for the mediocre front end performance
> of the K3 (compared with the professional-level performance that some of us
> had hoped for.)
>
>