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Reviews For: Kenwood SM-220 Station Monitor

Category: Tools & Test Equipment for the amateur radio work bench

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Review Summary For : Kenwood SM-220 Station Monitor
Reviews: 5MSRP:
Multifunction monitor oscilloscope and two-tone audio signal generator designed for use with the TS-520 and TS-820 transceivers.
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
K5DSQ Rating: 2015-09-10
Nice Station Monitor Time Owned: 6 to 12 months.
Purchased this unit to monitor my transmit signals on SSB, CW, PSK... as well as to check the linear operation of my legal limit amp. Helps makes proper loading a snap! Handles the high power level with ease. Wish more operators monitored their signals when transmitting at high microphone drive settings and power levels.
K0BNL Rating: 2013-02-06
Work great Time Owned: more than 12 months.
A very useful tool for any ham that wants to monitor their tansmitter / transceiver signal output. Very helpful if you use a linear amp.
WPE9JRL Rating: 2008-08-06
OK Station Monitor - BandScope Needs Help Time Owned: 6 to 12 months.
Very nice scope function for monitoring of transmitted signal. However, the BS-8, when used with my TS-870 always drifted in its receive spectral display rendering the bandscope function near useless.

This is an old unit being used with newer radio's. We need to be reminded that it was designed in the late 1970's and produced up through the late 1980's. It is a dated unit and performs accordingly.

To sum up the unit, the monitor function for transmit is very useful but the BS-8 adaptor is flawed (drift) and needs to be constantly centered. It can be used successfully with a constant tweek to the centering control to keep the display "on freq".

PE1NPG Rating: 2008-08-05
Still Usefull Time Owned: 3 to 6 months.
I purchased a complete TS510 line from a older (retiring) Ham, including tuner, ExtVFO, the scope and 2m transverters. cleaned up the external and internal and added a external DDS VFO for working digimodes and CW. (via the fixed freq. crystal position)
1.4 meters wide set of pure fun! The stationmonitor is excellent for monitoring digimode output and CW envelope. Panoramic view is awfull, not sensitive enough and drifting, as mentioned before.
ZS1AN Rating: 2004-05-19
A nice monitor oscilloscope but not a great bandscope Time Owned: 0 to 3 months.
The SM-220 is an oscilloscope and two-tone audio generator designed to test the output of an SSB transceiver. Although I have not owned it for long, since there were no reviews on I thought you might be interested in a functional description and some initial comments from a new owner.

It has the following functions:

1. Monitor oscilloscope to monitor the output waveform, either with input from the built-in two-tone audio signal generator or with normal speeach or CW modulation. It includes an attenuator allowing full-scale signal levels from 40 W to 2 KW (5 minutes max).

2. Pan display "bandscope" displaying the amplitude of nearby signals. This requires the optional BS-5 or BS-8 units - the BS-5 for rigs with a 3.395 MHz IF, the latter for rigs with an 8.83 MHz IF.

3. Trapezoid waveform observation for checking the linearity of a power amplifier.

4. RTTY cross pattern observation.

5. Use as a general purpose single-trace 10 MHz oscilloscope.

I acquired one fairly inexpensively as it had a faulty BS-8 unit, which I managed to fix. The BS-8 consists of a VCO which is swept by the oscilloscope time-base, a mixer, 455 KHz IF amplifier and detector. The output of the detector is internally connected to the Y deflection plates to display signal amplitude as the frequency is swept 20 KHz or 100 KHz either side of the receive frequency.

The bandscope suffers from poor sensitivity - it requires at least an S5 signal to register even a faint blip on the scope. So it is not much use for trawling the amateur bands in this part of the world, but great fun playing in the commercial broadcast bands (including seeking out a Digital Radio Mondiale signal that sounds like white noise but shows up on the band scope).

Mine also drifts, with the centre point moving about one third of the oscilloscope screen width from switch on until fully warmed up (which takes about 30 minutes). Unfortunately the centre frequency adjustment is via a trimmer accessed through a small hole in the side of the unit, so it is not convenient to adjust it to compensate for the drift. Fortunately the bandscope unit includes a crystal marker oscillator on the IF centre frequency, so at least one can see this on the display. However the drift may be due to my repair, which involved replacing the inductor and some of the capacitors in the VCO unit, which had been retuned for a different IF frequency.

Speaking of which, I am using it with the 8.83 MHz IF output on the back of my TS-850S. The TS-520S and TS-820S for which it was originally designed do not have an IF output socket, so internal modifications (explained in the manual) are required to feed the BS-5 or BS-8.

The monitor oscilloscope and two-tone test generator work well, allowing me to view either the SSB envelope or the CW keying waveform of the rig, including slight ALC overshoot on the first "dit" as mentioned in the ARRL test report. The two-tone generator provides tones of 1 KHz and 1.575 KHz which can be activated independently or together and or of the right level to be fed into the microphone input of the TS-850S.

I also teach the RAE so it is great to be able to demonstrate the waveforms associated with AM, SSB and CW signals to my classes.

Overall a nice addition to the shack, although the bandscope is more of a fun toy that a useful operating accessory.