EMRFD Message Archive 1665

Message Date From Subject
1665 2008-05-24 07:29:46 bkopski EXPERIMENTAL METHODS - THE HARDWARE PART
Hi All -

About two years ago I began putting together an HB 20 M SSB rig based
in part on the popular BITX design. But – since this transceiver
would be my first SSB experience - I wanted first to build, test,
modify, etc. each functional block by itself and then interconnect
them to ultimately form the transceiver. I needed a simple low cost
way to do all this experimenting and "interconnecting" and I chose to
use RCA (phono) connectors to aid in this. The resulting module-by-
module transceiver worked out very well.

Since then I've done a lot of varied experimenting with other stuff
and I continued to employ the same RCA connector concept. Now
however instead of building a final item out of the modules
themselves, I've come to use the module idea all by itself. Over
time I've accumulated many connectorized functional blocks that have
allowed me to more easily configure and evaluate a wide variety of rf
designs before committing to a final assembly. Think of these
functional blocks as child's blocks – both are fun to build – and
then build again - with!

Examples of individual functions include pads, terminations, an RLB,
amplifiers (EMRFD Table 2.2, SSD p147), MiniCircuits amplifiers, a
wide variety of filters, a crystal test fixture, mixers, product
detectors, 2:1 transformers, and so on. A partial collection is
shown in a photo as is one EMFRD amplifier. Also shown is a ~1 – 100
mHz rf sweeper design – "strung out" on my bench – using some of
these interconnected building blocks. Ultimately I hope to build the
final boxed-up sweeper using similar subcircuits but now assembled
all together in a single assembly and thus liberate these
connectorized modules for use in the next puesuit.

BTW – the board mounted RCA females are Mouser 161-4216 which work
very well in this application. (My last purchase was for 100
pieces!) And as pictured, there are a wide variety of RCA-type
connectors and adaptors available. I've also settled in on a simple
board power connector based on male (on the board) and female (on the
cable) pieces of 0.1" strip connectors. It all makes this kid's
blocks very easy and fun to play with!