Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Oct Sun 26, 2014 2:04 am


All times are UTC [ DST ]



Post New Topic Post Reply  [ 6 posts ] 
Author Message
 Post subject: Eico 625 and 7 volt tubes.
PostPosted: Aug Mon 26, 2013 12:02 am 
Member

Joined: May Thu 26, 2011 5:58 am
Posts: 1841
Location: Sterling, Va 20164
Does anyone have any info on testing 7 volt tubes with an Eico 625? My dad has a Philco Transitone that he wants to test the tubes from but his book does not list them. Thanks!

_________________
Consider me a straw in your haystack of success.


Top
 Profile  
 
 Post subject: Re: Eico 625 and 7 volt tubes.
PostPosted: Aug Mon 26, 2013 12:07 am 
Member
User avatar

Joined: Jul Sun 21, 2013 12:21 am
Posts: 3937
Location: Vieques,PR 00765 USA
Nominal filament voltage on "7 volt" tubes is 6.3 volts. ~Same as 6 volt tubes. Does the tester have a loctal socket for these tubes? If it does then the test data should be out there somewhere.

_________________
-Bill

Visit my homebrew page
www.sparkbench.com/homebrew/homebrew.html


Top
 Profile  
 
 Post subject: Re: Eico 625 and 7 volt tubes.
PostPosted: Aug Mon 26, 2013 12:49 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 7786
Location: Minnesota
Do you have a roll chart?, they are listed there. Look at the second column.

Dave


Top
 Profile  
 
 Post subject: Re: Eico 625 and 7 volt tubes.
PostPosted: Aug Mon 26, 2013 6:34 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1541
Location: Oswego, NY, USA
Also remember that you can pretty much obtain/apply any filament voltage to a tube under test, even if that voltage is not provided as a choice on the tester's panel, simply by readjusting the tester's Line Reg potentiometer (the large wire-wound pot on the tester's lower left panel) to obtain the precise voltage you're after. Some Loctal tubes (the "7" and "14" series) are a bit difficult (I think) to know exactly which filament voltage should be applied to them, because some tube handbooks (Sylvania, for example) list a "nominal" filament voltage as high as 7 volts (or 14 volts for the 14 series), but in reality, they run best at no higher than 6.3V or 12.6V; and if run continuously at 7 or 14 volts, they will burn out much sooner. Remember that the term "nominal" is not necessarily the voltage you should run a tube at, especially for hours at a time.

Fred


Top
 Profile  
 
 Post subject: Re: Eico 625 and 7 volt tubes.
PostPosted: Aug Tue 27, 2013 2:22 am 
Member

Joined: May Thu 26, 2011 5:58 am
Posts: 1841
Location: Sterling, Va 20164
Thanks guys. I will finally get these tubes tested.

_________________
Consider me a straw in your haystack of success.


Top
 Profile  
 
 Post subject: Re: Eico 625 and 7 volt tubes.
PostPosted: Aug Tue 27, 2013 3:48 pm 
Member

Joined: Jun Fri 19, 2009 6:34 pm
Posts: 4235
Location: Long Island
"7" and "14" series loctals are an exception to the rule that the first digit(s) of a tube number are the nominal heater voltage. The "7" and "14" were used to differentiate the loctal series from "6" and "12" which were used for octals. They are still 6.3-volt and 12.6-volt tubes, so you would set the heater voltage on your tube tester accordingly.

It is interesting to note that 1-volt loctals have "1L" numbers such as 1LC6, where the "L" is for loctal, but they did not follow this practice with the other voltages--perhaps because they were afraid they'd run out of numbers if they did!

_________________
"Hell, there are no rules here--we're trying to accomplish something!"

Thomas A. Edison


Top
 Profile  
 
Post New Topic Post Reply  [ 6 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: pixellany and 5 guests



Search for:
Jump to:  




















Privacy Policy :: Powered by phpBB