In reply to your question:

1. For the Intercom Amplifier Fidelity Test (EMER FZ 254/3 para 68) the
specification is as follows:

Adjust the input to give an output of +4.3 dB at 400 Hz
at 150 Hz the output should not be less than - 1.8 dB
at 5,000 Hz the output should not be less than +1.24 dB


2. Under the "A" Sender Tests (same EMER para 157) the modulator should
do the following:

"As measured across the audio oscillaror terminals, the input voltage
required for 75% modulation shall not exceed:
1 V (rms) at 400 cps
5 V (rms) at 150 cps
7 V (rms) at 5,000 cps"

3. As far as the original capsules are concerned, I have always found
them to be very low in output. I attribute this to age and stiffness of
the cone. I know someone who used to use an adjustable, amplified mic for his
19 Set. We did not use it often but it seemed to work fine. I replaced
the guts of a capsule with a small, plastic 40 ohm Radio Shack speaker
(perfect fit). That arrangement is the the best mic that I have.

4. Hope this is of some help. Checking on an oscilloscope is the only
way to tell what is really happening.

Cheers...Dave

Do you own a serviceable 19 Set? Yes