[ARC5] Reading Lists - Yahoo etc

[Leslie Smith]

Morning all,

One recent post mentioned "Yahoo" as a vehicle for on-going comms.
between people/list-readers interested in "command" gear.  

I'm a member of "RegenRx" - a group that follows the technique of
regeneration/feedback in simple receivers.  I'm sure anyone reading this
posting will know about this technique.

One point mentioned on this (ARC-5) list was that an effective reading
list must include the facility  to search posting over times-past (or
postings-past) to retrieve info on any topic discussed earlier.   I
certainly do that.   I have a useful collection of postings on topics
like "screw sizes", "set identification", paintwork and so on.  I think
you get my drift.

Returning to RegenRx, I searched 10 years of postings from that web list
for the humble single-tube Twinplex receiver.  I call the result of my 
searching a "trawling" - in other words I edited the result of my search
for postings about the Twinplex.  I called the result (a text file with
an index) a "Trawling".   I collected some circuits to illustrate the
points I found and put the lot into a folder.  You can read a fragment
of my work below my 'signature'.  I thought the exercise was rather like
throwing a net into the ocean.  Never know what you'll hook!    I'm
searching the RegenRx list now, on another topic.  It takes some time to
edit the files and write an index.

I try (as much as possible) to give credit to the individual who posted
the info I trawled - although that's sometimes hard to do without making
the fragments I found unreadable.  I thought about "ownership" of this
too.  That's largely an academic question, because everything is
"public" to list-members, but (in my view) a trawling should be the
non-commercial property of all list members.  However, some-one who
spent days (or weeks) panning the gold in a reading list might feel he
(or she) owned the amalgamation of their effort.  I don't - so I leave
it to the list-owner to figure that problem.  That's a rather socialist
view, but I'm rather partial to enterprises that focus on the well-being
of a society - even a humble society that things dusty old radios are
interesting.

I mentioned earlier that a group called ARC-5radio already exists as 
Yahoo group.  Maybe this group could negotiate with the list-owner about
some rules of engagement.  

Finally, I note some discussion on the RegenRx list to the effect that
Yahoo itself may be under a cloud.  Ha!  
I hope list-readers find this posting helpful.

Les

                                    ж-ж-ж  Sample Trawling on Twinplex
                                    ззххйй

                  o-o-o   Index.  o-o-o

Section            Subject
  1.        Introduction
  2.        Selecting a basic regenerative receiver.
  3.        Sensitivity
  4.        Tubes & Configurations used in the Twinplex.
  5.        The First Article on the Twinplex.
  6.        Construction - Techniques and "How To"  
  7.        The Regeneration Control - getting it smooth.
  8.        B+ supply in the Twinplex Receiver
  9.        Comparison with other (regenerative) receivers.
 10.        Debugging 
 11.        The Twinplex "on-the-air".
 12.        Conclusion (empty at the moment)

            Copyright - contents of this file is available for non
               -commercial use to any list member. (List name: RegenRx)
            To obtain permission for commercial use - write to List
            Owner.

1.         o-o-o Introduction. The Twinplex Single Tube Regen o-o-o

(1.1)  In the '30s a simple twin-triode receiver appeared.  It became
known as "the twinplex".  This set was a humble twin-triode; the first
triode in the pair was used as a  detector; the the second triode drove
high impedance headphones.  This configuration was denoted as 0-V-1; no
RF amplifier, followed by the detector and a single stage of audio
amplification.  "My" version of the twinplex came straight from the ARRL
handbook.  This simple set has remarkable sensitivity.  This set of
notes is a simple compilation of comments from Yahoo's RegenRx reading
list, grouped under topics such as configuration/tubes used,
sensitivity, construction and so on.  For a beginner the twinplex is an
excellent place to start.  For "serious" communications a twinplex has
some deficiencies, but some readers from this list still use this humble
set every day.  Some even prefer it to commercial multi-tube designs.

1.2 I hope this collection of disparate postings from the RegenRx list
helps  other list-readers understand (and perhaps build) the simple
Twinplex radio receiver.


2.         o-o-o Selecting a Basic Regenerative Receiver. o-o-o

(2.1)  James Millen wrote "it is not so much the [circuit] diagram that
counts, but the manner in which the circuit is used."  He goes on to
mention heater wiring, capacitor types and coil characteristics.  In
other words pay attention to the components and style of construction.  
When Jim Millen wrote that "it's not the diagram that counts" he had
spent the previous year building TRF receiver "diagrams".  Few can match
this experience, and in science (and art) experience is a key element.  

(2.2)  Jim Millen isn't the only person who believes construction is the
keystone to success.  " ... I don't think there is any one particular
best Twinplex design. Properly made (and that's more about the
mechanical build quality than the circuit), they all work about the
same. It's a very simple design, with a few variations. Eg, audio
coupling (choke, RC, transformer),  different tubes (19, 3A5, 6SN7,
12AU7…) etc."  That's Rob (or Kyoritsu) from RegenRx.

I have about 10 points in the file.  The collection is more than 6000
words, so there has been a lot of interest (and comment) about this
simple set.  In the long run I hope my work will catch the interest of
interested folk (and I hope especially just-teens developing an interest
in radio/electronics) and (maybe turn a passing interest into a
life-long hobby or career.

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