[R-390] HP410B rectifier tubes

[wabate]

Barry,

You sure you don't want a 2-O1C?  That's what I have in my 410B.  You 
can use the EA53 but it requires a different plate contact and attaching 
spring.  Also the filament voltage is different.  Don't know if HP made 
a design change or if they just allowed for a different repair part.  I 
have an NOS HP replacement part, 2-O1C.  Let me know if you are interested.

73,

Bill, K3PGB

Barry wrote:

>Did some more digging.  With the cover off, I can measure the filament
>voltage for the EA53 while it is in circuit.  I had to crank the resistor
>quite a bit farther "up" to get 6.3VAC across the filament.  This did cause
>the probe to get really warm like it used to; however, the probe still
>doesn't check AC properly (low reading).
>
>I did some checking in the manual.  It states to check the resistance
>"below" the ballast tube with the ballast tube removed from the circuit.
>This should produce 4 to 6 ohms.  If it doesn't, most likely something has
>been "shorted" (I assume it means something has damaged the rectifier).
>Mine checks a little over 2 ohms, regardless of the setting of the variable
>resistor.  Looks like I probably do have a damaged EA53.  I checked the rest
>of the wiring and some of the test point voltages and nothing was
>particularly too badly awry.
>
>Looks like I'm back to looking for an EA53 :-(
>
>Brry - N4BUQ
>  
>