[ARC5] BC-230 / -430 "Four Pin Tube Bases" Not Needed.

[Glen Zook via ARC5]

In the late 1930s and throughout the 1940s, maybe even into the early 1950s, there were commercially manufactured adapters which allowed various octal based tubes to be used in place of the old, large pin, tubes.  I have a number of those adapters.

I have also wired adapters for 7-pin and 9-pin miniature tubes to allow them to be used in place of octal based tubes.  This is for applications that I don't have the octal tube but do have miniature tubes with the same electrical configuration.

One can use "perf board" for making adapters for specific substitution applications.  This is especially handy for those who do not have the facilities for making printed circuit boards.
 
Glen, K9STH 

Website:  http://k9sth.net


On Tuesday, October 14, 2014 10:35 AM, Ben Hall <kd5byb at gmail.com> wrote:
 


Hi Dave and list,

On 10/13/2014 9:27 PM, David Stinson wrote:
> In the original tubes, the leads to the tube elements were
> like 2 to 3 inches long.  It's not an issue with subbed tubes.

Excellent.  Being out sick today (my stomach feels like someone has 
punched it) I did get some time to think about how to make some adapters 
and made a model.  Lead length, while not as short as your method, is 
well below 2 inches:

<http://www.kd5byb.net/BC230/4to9adapter.jpg>

Some description:

1)  The socket is from the parts bin.  It does have a provision for a 
tube shield.  If I had a socket with the mounting "wings" but not the 
tube shield provision...I would have used it.  :)

2)  The tube pins will be made from brass.  McMaster-Carr has both 1/8" 
and 5/16" brass rod that is inexpensive.

3)  For my prototype, the green PCB will not be a PCB...just a piece of 
FR-4 laminate without any copper.

4)  For my prototype, the brass pins will be a press-fit into the PCB 
and retained with a dab of epoxy.  If or not this will survive an 
insertion / removal cycle has yet to be seen.

5)  When I get a PCB made, the brass pins will be soldered into 
plated-thru holes in the PCB.  This should be pretty robust and survive 
insertion / removal cycles.

6)  For my prototype, the wiring will be done as in your photos Dave - 
point to point wiring.  The wiring will connect to the brass pins by 
soldering to the top peeking thru the board on the bottom.  (in the 
diagram, the brass pins are not seen poking thru.  I was lazy when I 
made the solid-model.)

7)  When I get a PCB made, I'm not sure if I want to have the 
connections be on the PCB or not.  We'll see.

8)  The screw is a 4-40 brass machine screw...the nuts are small-pattern 
4-40 hex nuts.

Comments welcome.  :)

> I need to re-do my bias adjustment work.
> My results weren't consistant so need to nail that down.

Roger that.  When I get mine up and working, let me know and I'll see if 
I can duplicate your results.

thanks much and 73,
ben, kd5byb


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