There is a "Tech Sheet" available on the Svetlana Tube Company web page which describes conversion of a Dentron GLA 1000 B to their current production EL-509 tube(s). A cost effective alternative to NOS D-50 or 6LQ6/6JE6 replacement tubes. This is a great conversion reference souce, but IMO the modification "update" is not very complete.
The tube cathode current should be cut off or reduced when the unit is in the standby (receive) mode. This is not a problem as the original tr relay has an extra set of unused contacts which are ideal for the task. I have written the "cathode current cut off" modification text into an article, which you may down load free from the Sonic Web Server Amateur Radio Page. Feel free to Email me should you have questions about the package. Please use the included cathode lead cutoff circuit paperwork "text" I've set up as a basic idea guide for your retrofit. A more formal writeup will come as time allows. A scanned image of the original gla amplifier circuit diagram, and my suggestions are included. Both the gif and pdf file formats are supported.
The download page also provides a copy of an old Ham Radio Mag (rip) article for
reference only and the Dentron factory blurb sheet for the ten meter mod as
often listed should be L7 (input toroid coil) - 5 turns 18 guage enam wire on T50-6
Amidon core - C35 (input section, towards tranceiver) - 150 pF 500V capacitor,
C36 (input section, towards cathodes) - 36 pF 500V capacitor.
These values were offered by other sources and are not confirmed by me. The Ham Radio
Magazine text has technical problems, don't use it as a reference for your amplifier
repairs or retrofit.
Far Circuits now offers up a batch of PC boards for the Svetlana EL-509 retrofit, but more work needs to be done. No one has come up with the proper tuned input part values for use with the much different drive impedance of the Svetlana Tubes. It's not hard, but no one has done the home work yet. I'll include some soluctions into my text when I have time to work out the proper input circuit part values.
enjoy
skipp
We/I get a lot of Email from visitors who drop into these file down load description pages
via a web search "engine" (like Google). Vistors are not able to locate the file download
icon for that specific description page. There is a simple way to find the file download
icons on the main http://www.radiowrench.com/sonic sonic
web page...
First and best: Use the menu icon just below to the main sonic page.
Second: Back space out the page your now looking at in your browser location line. As an example,
using the http://www.radiowrench.com/sonic.so2004.html description page. Remove the last portion
of the web location with the keyboard back space key to read http://www.radiowrench.com/sonic
then press your Enter Key to reload the main sonic page "just in front" which would probably
has the inforamation you're looking for. This works on most of the current browsers at most web
sites.
Third: You can always contact me using the Email Icon below. I'll try to get a back to you
asap with a practical answer.
Enjoy, come back when you can...