Since my 440S goes down to 30 kHz, I want to find an IF output to use
it as a tuned radio frequency receiver (poor man's spectrum analyzer).
I do some ultrasound in air measurements, and my acoustical gear is
calibrated only out to 100 kHz, while there is interest in the range
from 100 kHz up to 300 kHz. I sent the ac output from a commercial sound
level meter (and elegant audio spectrum analyzer). Apparently the 100
kHz preamp and succeeding post amps also purveys higher frequencies (ut
not normally processed for spectra and display). Using a microphone
whose sensitivity is undeclared above 40 kHz, and feeding the audio post
amp output into the antenna input of the TS-440S, I was able to depict
the sound from the jingling of keys (a profuse source of ultrasound
pulses and pings). Signal activity from the keys jingling was strong
30-50 KHZ and was detectable as high as 500 kHz.
Ages ago, I used a "Benham Wave Analyzer" to make ultrasound
measurements from 15 kHz to 250 kHz. The Benham analyzer was a stable
heterodyne analyzer that fed the signal through a 455 kHz IF (old AM
favorite), then a CW detector, the measuremnt heterodyne being 4 kHz as
I recall. I spend many hours zeroing n on CW ultrasound signals, and
using a precision decade attenuator to measure the ultrasound value.
If the 440S CW system can be set to no AGC (linear I/O) I can reproduce
the Benham action, using the 440S tuning frequency as being accurate.
I need some hits as to what adjustments I can make on the 440S and were
to pick off desired signals. I have a precision Ballentine VTVM to use
as a precision second detector (in place of the S-Meter.
Any Suggestions?
complex messages can be sent to my e-mail a.campanella@[EMAIL PROTECTED]
my web page www.campanellaacoustics.com for other info.
Angelo Campanella
W8EDR
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