[ARC5] Four pin to nine pin adapter fit check

[Ben Hall]

Good evening all,

Did the fit-check this evening.

<http://www.kd5byb.net/BC230/fit_check.jpg>

Issues:

1)  The adapter does have a little interference with the original 
VT-25/52 tube retainers as it is being inserted.  The widest part of the 
9-pin socket is slightly wider than the inside diameter of the ring. 
You've got to insert it at an angle until it clears the ring, then all 
is well.  If I change all the nuts from regular pattern 4-40 nuts to 
small pattern nuts, this might go away.

If one were to remove the retaining rings (by removing the two screws 
with the red compound on them) this would not be an issue.  I don't like 
this idea...as I know as soon as I remove mine...I'll lose them!  :(

With a 7-pin socket being smaller, this will not be an issue with the 
7-pin variant.

2)  The heads of the two mounting screws on the underside of the adapter 
prevent the adapter from sitting flush to the VT-25/52 tube socket.  The 
whole thing can "rock" back and forth.  This can be remedied by changing 
the round-head screws for flat-head screws that sit flush.

3)  My prototype used a "junk box" 9-pin socket that was designed to be 
used with a tube shield.  Without the shield, the tube isn't retained 
very well in the socket - it can "flop" back and forth.  I don't know if 
this is because the socket I used was designed for a shield, or if all 
9-pin sockets have pins that have some axial "slop."  I have some units 
in the mail from the e-place and will see if they are better.

I don't want to require the use of tube shields.

James Millen is reported to have said that you can't build a good tube 
radio without a Mechanical Engineer.  If I recall correctly, his point 
was that good mechanical construction was just as important as good 
electrical design.  :)

Thanks much to all for the words of support.  I'll keep posting as I 
make progress.  :)

thanks much and 73,
ben, KD5BYB