[ARC5] Switching the dreaded B+ line

Sun Apr 2 10:47:42 EDT 2017

No worries with the relay issue!I originally started with a BC-441 that was gutted with only the meter, binding posts and thermocouple remaining.I used a  readily available 5a DPDT relay to serve in the T/R role and made a toroid transformer to run the the thermocouple.To "do no harm" and not drill holes in the chassis, stick-on velcro pieces were used to fasten the relay in place. A blob of silicone will work too, but I prefer velcro for easy replacement. Both offer a certain amount of noise damping too.
The same applies to the relays missing in the tx . There are lots of small plastic encased relays that will fit in there.You don't necessarily need the originals if the goal is to just get it working. All you need it the proper coil voltages and current capability.
The same applied in my homebrew version of the bc-456 (CW edition). A standard  power type relay was used for keying and it works just fine. ( even though the nitty gritty specs gave me pause) I was encouraged by the list that it would work-and it did!

    On Saturday, April 1, 2017 10:02 PM, Leslie Smith <vk2bcu at operamail.com> wrote:

 Hello Jim,

Your question was:  "Why not use the general scheme provided by that
excellent fellow, Dave Stinson, to put a "command" transmitter on the
air?"  Great question.

 Dave's notes are priceless, BUT his scheme assumes several things.  It
 assumes a control box (to switch the aerial (eg BC-422)  between a
 transmitter and receiver.  It assumes "your" transmitter is complete
 (sort-of) and that the relays etc are present.  Dave's scheme deals
 only with the transmitter, and not a transmitter-receiver pair.  I
 don't have an means of controlling ANY simple transmitter or receiver
 pair (such as a BC-442 or BC451), and I'll bet there are a lot of
 people in the same boat. 

I'm trying to devise a "general" scheme to get these "command" sets on
the air, and not just "command" sets.  More than that want to create a
set of notes that a 13 year old in New York or New Mexico can follow. 
Now, my friend, Ken Gordan (who I think has a typical command
transmitter) does NOT have a rack.  In Ken's BC-459 the two relays of
interest (K-53 etc) are missing.  I see MANY sets on eBay in this
condition.  (BTW - I'll advertise for Ken!  If anyone has a rack and
matching 12 pin connector, send it to him.  Ken will hate me for doing
this, but he'll be pleased to get the rack and connector!!)

Now I spoke to Ken about saving these sets.  He said, "LOTS of command
gear is going to land-fill NOW."  I will bet $1 to a con-man's wife
that for every "command" set you see on eBay 10 are going to the dump. 
How do we save these sets?  Answer:  Get them on the air, and that means
showing your 13 year old (in Maine or Montana) how to do that.  

Ken wants to get a basic "pair" on 40m, with a dyno and haul it round to
field days.  Get kids interested.  Isn't this how we all got started?
Any simple set (with just 3 tubes) that is working will generate a "wow"
if it looks "nice".  Once interest is generated ANY set that is old or
battered is valuable IF IT GETS A 13yo ON THE AIR.  (In Kansas or
Kentucky.)  You have a battered set?  Show a kid how to make it "nice". 
Teach that kid the value of "nice" and working with tools!  Make America
GREAT again!!

So - that point is settled.  These sets need to be ON THE AIR - whether
in Alaska or Alberta.  If I take Ken as my "typical" fellow - no
modulator, no BC-456, no control box, and I want to get a whole rig on
the air, how would I do this?

My answer:  I designed a circuit that will match anything to anything. 
Rice-box to command transmitter.  Command transmitter to command
receiver.  Regen receiver to command transmitter.  OK, I've made that
point, and I made a prototype of my circuit.

You can see it (circuit and card) in the files on Yahoo ARC-5radio
(group)  I called it TRL - transmitter, receiver logic, get it?

That's my answer to your question.  If a set has the relay - use it.  If
the set doesn't have a relay, then I want my circuit (and notes when I'm
finished) will show how to do that.  

More than that, I want to make the set/circuit "nice" and one complaint
that I hear often is that keying K-53 is noisy.  BUT, if a switching
circuit was put "further back" it would be very easy to add a time delay
to K-53 coil (and solve 2 problems at once.  For people, (like Ken) all
this is simple, but for the 13 year old kid in Arizona or Arkansas, he
needs a diagram that works without a rack or a relay.  

Anyway, I'm collecting info (and experiences) about getting these sets
on the air.  The most difficult part - finding connectors (generally)
and a connector (specifically) for the rear panel.  I'm working on that
too - Pomona pins and a resin plug body.  

As  your idea about for keeping these sets "original" - that's fine if
you have an original set.  I have a "nice" ARA receiver, and one "almost
nice" transmitter.  (Plus some junk).  Most people don't have a nice set
- so preserve what you have, make it look nice and put it on the air.

That's what I think (but more importantly) - that's what Ken thinks and
KEN IS RIGHT.  HA!

Les
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