[R-390] Alternative to IERC tube shields

[Shoppa, Tim]

> Of course in the days of endless supply depots and every Allied Electronics,
> Radio Shack or corner drug-store with a tube tester (and a supply) is long
> gone. Other than very questionable Russian or Chinese new(er) manufactured
> lots we are stuck trying to glean good tubes out of an ever diminishing
> reserve.

Other than say 3TF7's and 26Z5W's and 6082's, I don't see any
shortage of 390/390A tubes. And 3TF7's and 26Z5W's are still
readily available (meaning hand over the bucks) if you
really want them. Most of the 390 and 390A
tubes are in such easy supply because of vast quantities of JAN
tubes liquidated from military stocks.

After I got my 390A's, I went out on tube buying sprees snapping up
cartons at hamfests and online; I carried around a "going price" list in
my pocket and made tally marks as I acquired them at lower and lower
and lower prices. I got a lot of tubes for not too many bucks.

I compare the price of tubes today from any of the online distributors
to prices I paid in my hometown 30 years ago, and my conclusion is
that I paid way way too much for tubes back then :-(. I mean, I remember
needing 0A2's and 6CL6's and 6AU6's and 6146A's for my Heath radios, and paying
an hour or two's worth of my puny wages for each. I compare it to today
where a couple minutes of my wages will buy any of them.

Tim.