[Milsurplus] SCR-269 & SCR-273 differences

[Dave]

G'day all,

I have a query about the differences between components of 
these two Radio Compass systems. SCR-269-* was used in 
aircraft with 12 or 24V electrics whereas the SCR-273-* 
appears to be (more or less) the equivalent for use in 
aircraft with only 12V electrics. The component of each 
system are as set out below - other components not mentioned 
such as cords and tuning cable/fittings are common to each 
system.

The receivers do have different frequency ranges.

My question is, why the different indicator units? I thought 
it might be just different illumination bulb voltages but 
the SCR-269 can be used on both 12 and 24v anyway. 
Functionally, can I use the 269 indicators on the 273?

I would like to build up functioning systems for both 
SCR-269 and SCR-273. I do have all the components for the 
269 and I have the receiver for the 273

I would be interested to hear from anyone who has spare 
components for the SCR-273 system particularly the control 
box BC-414. The two control boxes look identical except for 
the tuning ranges.


SCR-269 (12/24 volt)
Frequency ranges Band 1 - 200 to 410kc, Band 2 - 410 to 
850kc, Band 3 - 850 to 1750kc.

BC-433* receiver
BC-434* control box
LP-21* loop antenna
BK-22* relay
I-82* indicator Navigators
I-81* indicator Pilots
PL-112 connector


SCR-273 (12 volt)
Frequency ranges Band 1 - 150 to 325kc, Band 2 - 325 to 
695kc, Band 3 - 695 to 1500kc.

BC-413* receiver
BC-414* control box
LP-19* loop antenna
BK-21* relay
I-75* indicator Navigators
I-65* indicator Pilots
PL-117 connector

Cheers
Dave
VK4KDP