IDEA

Many things are much simpler to make if switching RF components is
avoided.

Historically, the most common connection type used for interchangeable
coils seems to have been the octal socket and plug. The practical cons
of this and similar solution are availability, lead length, and 1:1
tank-circuit to plug ratio.

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OBSERVATION

When I look at the long gold-plated multi-contact plug-in connections
on a PCI bus et similia, I see several advantages:

- many connections to play with, often used for large bandwidth
signals

- connections spread along one dimension, hence plugging more than one
RF-separate group of components on one card in one gesture seems
conceivable

- one board extends at 90deg from the other, adding useful real estate
within a small radius (cautions apply...)

- the plug-in board can itself hold structures with a vertical
component, such as small shielding enclosures

- multiple contacts can be used for grounding, effectively helping
keeping multiple component groups well separated, and also for other
low impedance connections

- last, but not trivial, a card could have some free flat space
opposite the contact edge for grabbing and pushing without touching
and stressing the components themselves.

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COMMENTS

In practice, I want to resuscitate a rough avatar of the HRO "tuning
drawers" of the 1930's.

As an example, I am designing a bi-directional triple-tuned circuit
around a triple variable capacitor, for use as a full coverage
preselector/output filter - potentially from LF to HF.

It would be nice to put three combinations of coils and capacitive
trimmers on a single card and stick it in to change bands. If that
were possible, it would be trivial to design some cards for broad
tuned coverage, others for a narrower band or even non-tuneable for a
single frequency - not using the variable capacitor.

As a matter of course, different LPF's could be swapped in the same
way.

This would be less convenient than switching, but would also obviate
the need of wafer switches, switching diodes, reed relays &c. &c. and
potentially introduce scope-oriented, not just frequency-oriented
modular flexibility.

If I could find blank two-face copper clad PCI cards in a few
different sizes I'd surely know how to put them to good use!

---------------------------------------------------

QUESTIONS:


- I don't recall seeing examples of this, including components or
groups of components that are
.. * multiple
.. * functionally separate
.. * RF-segregated
.. * RF-hot at the same time
.. * at successive stages on a signal path
.. * on a single plug-in card.

Other than the HRO drawers, are there any?


- Any suggestions for card and socket formats that are
.. * standardized
.. * widely available
.. * perf board or single / double copper clad
.. * blank or with minimal preset paths / swathes
.. * ...or just the gilt contact edge, on which a board could
be bolted/glued?


I hope I have indeed missed the classic elephant in the courtyard, and
that a solution is at hand at www dot whatanewbie dot com.... ;-)

Thanks in eager anticipation!

Filippo N1JPR / I2

On Apr 29, 1:52*pm, spamhog wrote:
QUESTIONS:

- I don't recall seeing examples of this, including components or
groups of components that are
. * * * * * multiple
. * * * * * functionally separate
. * * * * * RF-segregated
. * * * * * RF-hot at the same time
. * * * * * at successive stages on a signal path
. * * * * * on a single plug-in card.

Other than the HRO drawers, are there any?

I think Ten-Tec has a HF transceiver with plug-in modules, I don't
know exactly what's in each module.

The Norcal Sierra is a pretty spiffy implementation of I think exactly
what you are talking about. URL for a handbook article with really
nice pictures:

http://www.arrl.org/tis/info/pdf/96hb1789.pdf

Tim.

Thank you Tim, problem solved. As you said the Sierra multiband CW
transceiver proves the viability of edgecards for plug-in band-
specific subassemblies, the article even points out how simpler the
plug-in implementation is, compared to the switching solutions for the
same problem, citing Wayne Burdick, N6KR's older Safari-4.

After a bit of checking, the current sockets are these:
- Manufacturer: www.sullinscorp.com p.n. EBM25DRXH
- Digi-Key: p.n. S3355-ND

PBT/Phosphor Bronze, Contact Surface: .000010” Gold
Termination: .000100” Pure Tin, Matte
..156” [3.96mm] Contact Centers
50 total contacts, Dual Readout
..200” [5.08mm] Row Spacing; .137”[3.48] Long Dip Solder, straight
Mounting With .125" Hole

Pretty sure I can find similar edgecards & sockets around here.

Thanks again.

Filippo