Db Rear Panel Attenuator Output - Ramsey Electronics COM3010 User Manual

DETAILED INFORMATION

6.30 30 dB Rear Panel Attenuator Output.

The 30dB attenuator output on the back of the COM3010 can be used for a variety of external
hookups such as spectrum analyzers, modulation analyzers, and other test gear. It can also be
used to loop back into the receiver input on the front to obtain good frequency counts during
power testing.
The Receiver Input on the COM3010 is a sensitive circuit which is sent not only to the
Receiver, but also the Frequency Counters. It is recommended that the input is never driven
with more than +20dBm (100 mW) of signal. When keying a 100W (+50 dBm) radio into
the COM3010 power meter the 30dB attenuator will have about +20dB of signal on the
output; this is right at the limit of the Receiver Input.
The 30dB power attenuator is nominally 30dB of attenuation over the 100kHz to 1GHz band
of the COM3010.
The RF signal from the RF OUT jack to the 30dB attenuator output passes through cables,
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connectors, the main PCB, a relay, and the attenuator before it reaches the output jack on the
back. This chain of connections has a predictable amount of loss from front to back, and is in
part used during the power meter calibration in the lab. The following table will help if using
the 30dB output jack in another method of measuring power.
Do not reproduce or distribute.
Take the dBm reading at the output of the 30dB attenuator and the frequency under test, and
look up the closest value in the attenuator table below. Add this value to the result to find
the level present on the RF OUT jack. This will allow measurement of power and signal levels
lower than the COM3010 will display, which is limited to 0.1W.
Attenuator Table
MHz Atten
10 29.60
20 29.62
40 29.71
60 29.78
80 29.84
100 29.89
120 29.98
140 30.03
160 30.09
180 30.12
200 30.17
MHz Atten MHz
220 30.20
240 30.22
260 30.26
280 30.30
300 30.35
320 30.38
340 30.43
360 30.46
380 30.48
400 30.51
420 30.57
Atten MHz
440 30.59 660
460 30.63 680
480 30.68 700
500 30.71 720
520 30.75 740
540 30.72 760
560 30.80 780
580 30.79 800
600 30.85 820
620 30.89 840
640 30.90 860
80
Atten MHz Atten
30.93 880
30.99 900
31.01 920
31.03 940
31.12 960
31.15 980
31.17 1000
31.23
31.21
31.30
31.29
31.24
31.41
31.31
31.35
31.39
31.36
31.54