[NJARC] Fw: Selenium Rectifier replacement

[antqradio at sbcglobal.net]

BobOK, how does one not exceed 8.4 volts applied to the tube filaments when the TO battery pack has an A battery value of 9 volts (or higher when the battery pack was brand spanking new)?
Getting back to the original discussion, adding another 25 to 50 ohms to make up for the Selenium stack internal resistance does not significantly change B+ voltage.  In the TO, that 25 to 50 ohms is in well within the tolerance of the 2000 or so total ohms that drop the B+ to the A+ level needed for the TO tube filaments.  
Actually the three resistors in the filament circuit are 130 ohms (10%) + 950 ohms + 950 ohms (unknown tolerance) for a total of 2030 ohms give or take.  So the internal resistance of the Selenium stack is about 2% of the total dropping resistance at face value without considering resistor tolerance.
Adding that little bit of resistance might work for one specific line voltage but there is no guarantee that the line voltage won't vary day to day or hour to hour.  So what does one do then?
Funny, as you imply, NOS 1L6's are worth much more than a TO in average condition!Jim

      From: Robert Bennett <dino66 at optonline.net>
 To: antqradio at sbcglobal.net; njarc at mailman.qth.net 
 Sent: Sunday, April 17, 2016 5:45 PM
 Subject: RE: [NJARC] Fw: Selenium Rectifier replacement
   
When you replace the selenium rectifier in a trans oceanic, there was
usually a 130 ohm 3 watt resistor in line to drop the voltage. Regardless of
which type of diode you change to, the focus needs to be on the filament
string or "A" voltage. Zenith specification was not exceed 8.4 volts. You
may want to install a 1R5 installed in the socket of the 1L6 unless you have
a bunch of them or "Bill Gates" funding. I've used varying resistances of
3-5 watt resistors for the drop after replacement. 

Bob Bennett

-----Original Message-----
From: NJARC [mailto:njarc-bounces at mailman.qth.net] On Behalf Of
antqradio at sbcglobal.net
Sent: Sunday, April 17, 2016 3:30 PM
To: njarc at mailman.qth.net
Subject: [NJARC] Fw: Selenium Rectifier replacement

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