[Kenwood] SM-220 & Alternatives

[WD8ARZ]

I have a SM-220 with the 8 MHz Panadapter module and use it with my Icom 
IC-720 (not the A model).... and I love it!! Wont get rid of it as long as I 
can keep those two pieces of equipment working. Find it especially useful 
for detecting those elusive HF utility ssb stations that just got tuned 
through with out hearing anything, but get active while still in the viewing 
window bandwidth. Now you can see the signal pop up on the scope and you 
whip the dial back to them and monitor. Then there is the looking for the 
empty spaces in the ham bands to move a qso to. Real-time monitoring is hard 
to beat and really puts to shame the time delayed 'scan of the band' 
displays that are not in real time.

Like the rigs with built in displays, but there are some caveats among some 
of those (real time, expensive display replacement the whole rig down in the 
meantime, limited display features, etc). Some are very good and will spoil 
you forever. You will take it for granted until it doesnt work anymore or 
your on a different rig. But they are not exactly mobile rigs either if you 
use the same rig on base and mobile. Some of the smaller mobile rigs have 
some more elaborate displays, but are hard to see or use in a mobile anyway 
....

However there is an alternative: SDR xxx

There are a variety of Software Defined Radios that bring a lot to the party 
for a fair price. As an intro to this technology, I went with an SDR-IQ: 
http://www.rfspace.com/SDR-IQ.html 
http://www.universal-radio.com/catalog/commrxvr/0106.html

It is more than a receiver, but a great display of spectrum information to 
boot. It basically has replaced the SM-220 in my frequency of usage doing 
the same job of the SM-220, but a lot more. For about $500 you get, a 
receiver covering 500 Hz to 30 MHz in 1 Hz steps. (note the low end tuning 
range is 500 Hz, not 500 kHz). It features the fastest and highest 
resolution plug and play spectrum display available. The SDR-IQ comes with 
the latest version of SpectraVue software, and there are other software 
choices. It supports AM, WFM, USB, LSB, N-FM, DSB and CW with fully 
adjustable DSP Filter bandwidths and FFT sizes of 2048 to 262144 points. The 
resolution bandwidth is as low as 0.031 Hz. Plus!  Records and plays back 
spectrum segments up to 196 KHz wide with full demodulation and tuning 
capabilities. That means you can record a bandwidth of interest, then play 
back that file, tune through it as you would in real-time, change modes and 
filters settings, and listing to all that stuff you could not have heard in 
real-time by being limited to one or two frequencies of the moment (has two 
vfos that can output to left and right channels independently in any mode).

I prefer stand alone equipment when possible, but the SDR-IQ and a small 
laptop make for a very portable system. A preselector / amplifier is useful 
if not needed though. Limited front end filters in the SDR-IQ and lower 
front end gain than typical hf receivers is a factor. Long antenna's should 
have a preselector if you have strong signals near your listening area, and 
a pre-amp is nice on short and portable antenna's. I use a combo unit from 
MFJ 1020C for that purpose.

Yes, you can connect it to the I.F. receiver for a panadapter operation. You 
can also slave an external HF rig to the SDR-IQ so as you tune one the other 
tracks with it. Be careful about transmitting and damaging the front end of 
the SDR-IQ.

Have trouble coping a certain digital mode or signal? Record the band 
segment including that signal and others .... then play it back and play 
with the program / audio settings until you get it to work as you like it. 
Great for improving the learning curve because your using the same signal in 
the same propagation environment to make your changes and compare results 
to. DRM is an example. What are the besting settings for your DRM program, 
the best offset frequency to tune the system to for best error free copy?? 
Record a DRM signal then explore that to your hearts content until you work 
out those techniques.

Point being, I will always keep the SM-220, but also use the SDR-IQ with my 
TS480HX and FT-1000MP.

73 from Bill - WD8ARZ
http://hflink.net/qso/