[R-390] R-390a AGC Issue/Observation

[Roy Morgan]

On Apr 14, 2009, at 9:26 PM, <wb5uom at hughes.net> <wb5uom at hughes.net>  
wrote:

> A 5749 is the military designation for a 6BA6 is it not?

Yup.  More accurately 6BA6W (the Wruggedized version.)  My GE spec  
sheet for the 5749 mentions intermittent duty.

There may be a list of cross-types used in the R-390's.   Ah yes. Here  
it is.. Sorry I did not record who it was who compiled this useful  
list (not me). The "shields" collumn tells the IERC black heat  
dissipating shield number for that size tube:

R390A Tube Chart

Reference Tube  BETTER Function  Shields
V201  6DC6    RF Amplifier  5020-B
V202  6C4  6100  First Mixer  5020-B
V203  6C4  6100  Second Mixer  5020-B
V204  6C4  6100  Third Mixer  5020-B
V205  12AU7  5814A  Calibrator Osc  6020-B
V206  12AU7  5814A  100KHz Osc  6020-B
V207  6AK5W  5654  First Xtal Osc  5015-B
V401  6AK5W  5654  Second Xtal Osc  5015-B
V501  6BA6W  5749W  First IF Amplifier  5020-B
V502  6BA6W  5749W  Second IF amp  5020-B
V503  6BA6W  5749W  Third IF Amp  5020-B
V504  6AK6    Fourth IF Amp  5020-B
V505  6BA6W  5749W  BFO  5020-B
V506  12AU7  5814A  Detector  6020-B
V507  12AU7  5814A  Limiter  6020-B
V508  6BA6W  5749W  AGC Amp  5020-B
V509  12AU7  5814A  IF Cathode  6020-B
V601  12AU7  5814A  First AF Amp  6020-B
V602  12AU7  5814A  Second AF Amp  6020-B
V603  6AK6    AF out local  5020-B
V604  6AK6    AF out line  5020-B
V605  0A2  6626  Voltage Reg  5025-B
V701  6BA6W  5749W  VFO  5020-B
V801  26Z5W    Rectifier  6020-B
V802  26Z5W    Rectifier  6020-B
RT510  3TF7  TJ311M01  Current Reg  6025-B

Above is a little chart I made up of the R390A's tube complement and  
equivalent tube shield required. The tube shield numbers given are for  
the IERC black shields - the ones preferred to disipate the heat  
produced by the R390A tubes. The shiny metal tube shields should not  
be used because of poor performance and the reflection of heat back  
into the tube - however, the black IERC tube shields are now hard to  
find.


I looked in the Tube Data Sheet Locator
http://tdsl.duncanamps.com/tubesearch.php
for a substitute for the 6AK6 and did not find an american industrial  
number for it.


Roy

Roy Morgan
k1lky at earthlink.net
529 Cobb St.
Groton NY, 13073