[R-390] No Peak on T701

[Tim Shoppa]

> I attempted to perform the "ground E211 and measure the output on the
plate 
> of V204" test.  I'm not sure, but I may have 'scope problems.  In
order to 
> see the signal, I have to select a very small vertical deflection
value 
> (say 0.1V/div or less).  When I do this, the 'scope "wobulates" up and
down 
> on the screen on the order of 0.05V or more.  If I look at the output
of 
> the RF-IF output at F103, it is doing the same thing.
> I don't know if the power is dirty, the power supply is acting weird, 
> the 'scope is flaking, or what. 

Is the wobulation 60Hz/120Hz?

Could be anything from real 60Hz power supply hum in the radio, in
the scope, ground dfference between the two, etc.

As long as the wobulation isn't inside the scope, isolating the 60Hz
hum can make a world of difference.

Standard workaround is use smallish capacitors in series with the scope
probe
that will block 60Hz you do not want to see but not block the MHz
signals you want to see.

Typical values might be 100pF to 0.005uF.

Tim.