tubes age 102
I replaced my HP-410B a while ago with a much later one.... I had a spare 2-
01C probe for the ood one but my newer one needed a EA53. I about died
when I looked in all the usual places for a spare EA53 and found that "if" you
could find one they were selling nos for up to $100 each ! Heck my spare 2-
01C is selling for between $30 and $60 it seems.....
I finally found a web page of a tube dealer in Sweden. He had a nos EA53
listed in Swedish currancy and for kicks I sent an email asking what it
converted to in US Dollars.
Get this...... $8 US Dollars ! Total with shipping was $13.80 including a $3.50
fee for an order under $30 Euros! Amazing...... sure must be more EA53's over
there then here <grin>.
Now I'm checking to see if they have or can get a spare probe tube for my
favorite VTVM.... a 1970 General Radio 1806-A, an amazing instrument but with
the very small 7266 ceramic diode in the probe. And.... I checked ... he didn't
have any 3TF7's or 26Z5W's <grin> but lots of nos European and other military
types. Owner's name is Ralf.... fast email, fast shipping, nice guy. YMMV...
RBN Trading HB
Karvagen 5
SE-976 31 Lulea
Sweden
http://go.to/radiotubeshop Mike, W9WIS
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Subject: Re: [R-390] General R390 Help
Date: Mon, 1 Apr 2002 09:03:29 -0800
Leroy, If you have to part with a 100.00 or so AUS or US for a tube tester for your
R390. why not hack an old 5 tube AM radio and a meter into a tube tester? If you
can find a 12 volt filament transformer with a center tap (6.3) and a 100 - 300
volt B+ winding you can build a tester. As you only need to test a select number
of tubes, you can wire one socket for each type. A couple switches for the dual
triodes can be keep it simple. Testers are relative. You can look at the tube
manual (on line some where) and find the expected current for a grid voltage.
Most testers tie the tube up as a triode (for short tests) and vary the grid voltage
to get a mid scale meter reading. The real test for R390 or A tubes come from
use in circuit and judging the noise. These are all relative test. This one is
better than that one. And you use the best of what you can get. The exact value
is not known. Most tube testers just weeds out the shorts and real dead
emitters.
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