[Drake] Re: Drake 7 line wattmeter diodes.

[Garey Barrell]

Hank -

The AA119 is equivalent to a 1N60 according to a reference I have.   The 
1N60 is a germanium diode, and the AA119 is a point-contact germanium 
diode. 

The AA119 is highly respected as a detector by the crystal set experts 
as the most sensitive available.

To get accurate, very low power readings, you would probably have to go 
with the AA119, although I suspect you wouldn't be able to tell the 
difference with a 1N60 OR a 1N270 under "real-world" conditions.   Keep 
in mind that the wattmeter is specified as +/- 5% of reading plus 1%  
_OF FULL SCALE_ .   So on the MN2700 you start out with a +/- 2W error 
and then add +/- 5% of the the reading to that.    Once you get past the 
square-law region, all cats are gray!

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
<http://hr99.home.mindspring.com/R-4C_Servicez/>



HENRY PFIZENMAYER wrote:

>Anybody know what the diodes are in the MN2700 wattmeter ?  I suspect they
>are the same in the WH7. They call em AA119 in the MN2700. I see the same
>diodes in the TR7 wattmeter.  I kinda suspect they are germaniums like a
>1N270 based on how well the SWR reading  still works at low power. I am
>asking before I unsolder one to see what the forward is on them. Maybe
>someone knows what they used- and where to get replacements .
>
>Rgds- Hank K7HP
>  
>