[Milsurplus] BC348 - Q model question

[jphutch60bj]

Specific to BC348-Q  converter tube VT150 aka 6SA7.

To sniff out the actual frequency being generated by the Local 
Oscillator circuit, would that be best measured from the Cathode pin #6 
or from the Grid 1 pin #5 ?

Don't want to shift the frequency, or at least minimize it, through a 
25pF  cap to my frequency counter?  Grid or Cathode to ground?

I  need to see ~15mV for my counter to work.

Thanks for your 2 cents.