Hello Renato,

Hi!
I have a selective voltmeter Wandel & Goltermann TFH-2.
I tried to listen our  136 khz qso but I was not able to listen (i have a

multiturn loop homemade, 1 m. diameter, tuned via a variable capacitor. The
signal >is amplified by a cascode bi-Fet)

I think my selective voltmeter is too little sensitive (it is able to

measure  -40 to + 40 dB).

I think it is possible to modify it!
Have you modified it?
Can you help me?
or must I  put it in in the garbage :-((((  ?
Thanks and best regards
Renato IK2WYS

you are right, - 40 dB, is not sensitive enough (if it is -40 dBm, this is
equivalent to about 2 mV sensitivity, what you need would be at least about
-110 dBm. You might be able to increase the sensitivity with a
pre-amplifier.

However, don't through it away, those selective voltmeter do an excellent
job to measure the near-field of a transmitting station, and for that
purpose the sensitivity should be ok! Anyhow, don't through it away,
whatever you do ... those old instruments have a lot of components that
might be usable for LF applications ...

Vy 73

Geri, DK8KW (W1KW)