[ARC5] BC-221-J vs BC-221-T or what?

[Roy Morgan]

On Feb 12, 2016, at 7:38 PM, Don Merz via ARC5 <arc5 at mailman.qth.net> wrote:

> I guess the time has come for me to keep one of these in the shack. I have had literally dozens of them go through my hands over the years. Now I have two here and one of them is going to stay. But which one? The J model is in lesser condition. The T model is almost like new. Both have AC supplies in them--the one in the T model might be a factory supply. The one in the J model is almost certainly homebrew. Both have the spare tubes and hex wrench where they ought to be. Both have the correct calibration books. Both were made by Zenith. 
> 
> Is there any reason to prefer one over the other except overall condition?

Yes, there is a very strong reason. I has to do with the principle of inverse perversity, the text of my Law about this is below for your consideration (and bemusement).  In short, if you keep both, neither one will ever fail.

> I have not tested them yet. But it does not seem like they would be hard to get running.

Just apply power and check for operation.

> Is there an achilles heel in them that I should check?

Only the six hundred henry audio choke (yes, six hundred henries).  But wait: if it is open, parallel it with a 100 K resistor and the thing will run.

I do have some of the articles published about the LM and BC-221 frequency meters and am glad to either email them or mount them on the virtual disk drive in the sky.



Morgan's Law of Inverse Perversity:

If you have no spare for a critical part or tube, that part will fail at the most inopportune time.  
If you do have a spare, or spares, the original one will never fail and you'll never use the spare.

Troubleshooting Corollary:

If you have no information on an obscure failure mode, that failure will happen to you at the most inopportune time.  
If you do have complete, detailed information, the system will never fail in that way.

Tool Corollary, inspired by Barney:

If a job requires a special tool, and you have one handy, you'll almost never need to use it.
If you can't find the tool, and you buy or make a new one, the old one will show up soon. Then you'll have two.

Brad Thompson’s corollary for unfindable parts:
At the time when it's needed, a replacement component will be nowhere to be found.

Murphy's law for electronic technicians: The suspect part(s) that will probably have to be replaced will be in the most inaccessible location on the chassis.
  - Jim ~ N5MSJ

(Bonus related item):
Morgan’s Law of Aging Memory:

As we get older, we gain more wisdom.
Since our minds have limited capacity, the wisdom pushes out the memory.


Roy

Roy Morgan
k1lky68 at gmail.com
K1LKY Since 1958