At 05:20 PM 5/13/2007, jeremy-ca wrote:
>I dont care to be called an idiot and I demand an apology. Moderator please
>take note.
>
>My comment was directed at what appeared to be the same relay as used by
>Ameritron and if it was the same then $45 is a rip off. However several
>prior posters were talking about 2 different relays and then you cleared up
>the confusion. Our posts crossed at the same time.
>
>BTW, remind me to not waste any money on your products as you apparently
>dont know how conduct yourself in front of potential customers.
>
>Ive worked in RF R&D most of my life so Im fully cognizant on how to design
>and test a switching system for something as basic as HF. A network analyzer
>takes most of the guesswork out of what some view as hard work.
The VNA might take the guesswork out of some of the measurements, but
doesn't tell you much about how to change the design to make it
"better". And for using "non-RF" components in RF applications
(which is what most amateur market relay boxes are.. they are NOT
clever stripline designs like DowKey uses) there's an awful lot of
craft and art to the design, probably moreso than straightforward RF
circuit design. (Unless someone's been out building HFSS models for relays).
The VNA just tells you "good", "bad", or "about the same"... but
doesn't tell you "make the box 1/4" taller so the parasitic C is
less".. that comes from either mindnumbing analysis (probably a waste
of time) or good old empiricism (try a bunch of different ideas, and
see what works).
And, a lot of what goes into amateur products (or pro products for
that matter) is non-RF related.. manufacturing cost, durability,
shipping, etc. all factor into component choices. I've seen
products (not in the ham market, and not RF related) that were
originally designed around the ready availability of a particular
surplus component. Then, when the surplus supply ran out, the mfr
had to go out and have custom parts made to duplicate a long
discontinued WW-II vintage part. That drove the Bill of Materials
(BOM) cost through the roof... especially for replacement parts for
the original widgets, and drove a completely new design.
>When KQ2M operated my station 1987-95, I designed and built all of the
>elaborate stack switching and elevation steering for a 4 stack of yagis on
>20, 15 & 10 as well as the pattern switching for 160 & 80 antennas. Specs
>were so tight that amp tuning never changed even when several relays and
>networks were in the signal path. Performance was obvious in the contest
>scores.
Just out of curiosity.. did those relay boxes work that well in the
initial design, or were there any design changes? Do you think you
might have just "gotten lucky" in the design and component selection
in the 80s?
I've been casually measuring a variety of off the shelf relays over
the past year or so, and there's huge variations between seemingly
identical relay designs from multiple manufacturers.
Jim, W6RMK
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