[Elecraft] K3 and SM-220

Mon Oct 11 00:36:52 EDT 2010

On Sun, 10 Oct 2010 15:02:10 -0800, Jim Wiley <jwiley at alaska.net>
wrote:

Thanks, Jim.

I suspect the SM-220 and SM-230 are pretty much the same.

I've had this SM-230 since I bought a TS-950s in the mid 80s and have
used Panadapters of one kind or another since then.

I went to the Belton, TX ham fest last weekend and saw an SM-230 for
sale.  It was mint and the guy wanted $600 for it.  Now if I can sell
mine for that I can get a P3 ;o)

Once again, thanks for the comments.

73,

Tom, N5GE

K3 #806 with SUB RX, PR6, 
KRC2 and K144XV
K3 #1055 with PR6 and XV432
W1, 2 W2's and other small kits

QCWA Life Member 35102

n5ge at n5ge.com
http://www.n5ge.com
http://www.swotrc.net

>Don't know.  Never had occasion to use or look inside a SM-230.  My 
>experience is limited to the SM-220.  Perhaps someone else on this list 
>has the info you need.  However, all that being said, it would not 
>surprise me if the band-scope option used the same module for both 
>units.  If the SM-230 used a module called the BS-8, it is possibly the 
>same unit.  If the part number is different, then some more examination 
>would be needed.  
>
>
>Keep in mind, however, how the band scope works.  It is basically an 
>electronically tuned receiver that derives its tuning voltage from the 
>horizontal sweep oscillator in the band scope - which at root is 
>basically an oscilloscope.  The sawtooth signal from the sweep 
>oscillator drives a varactor (voltage variable capacitor) diode 
>connected to the tank circuit of the BS-8 oscillator.  The oscillator 
>then sweeps back and forth around the 8.83 MHz IF, either plus or minus 
>20 kHz or plus or minus 100 kHz,  depending on the bandwidth selected.  
>The BS-8 oscillator signal is mixed with the 8.83 MHz IF signal from the 
>radio, resulting in a new IF (for the band scope only) that is amplified 
>and detected, then sent to the SM-220 (or SM-230) vertical amplifier.  
>The resulting varying amplitude signal then corresponds  approximately 
>to the level of any signals present ,   which then appear as "pips" on 
>the spectrum-display screen.  Most all spectrum analyzers work this way, 
>at least the "conventional" analog types.  The Elecraft P3 is probably 
>rather different in how the detection and display process is 
>implemented, but remember it has access to a whole box full of software 
>tools that the older SM-220 and SM-230 do not have.
>
>
>In order for the SM-220 or SM-230 to display signals from the K3, or any 
>other transceiver, all that is needed is for the band-scope oscillator 
>to be able to sweep back and forth  within the desired offset from the 
>transceiver IF, and  for the band-scope unit's "front end" to be able to 
>tune to the desired transceiver IF.  Everything else from that point on 
>is pretty much independent of  what radio it is connected to .  Some 
>band-scope adaptors don't even have a tunable RF front end, instead they 
>rely on the transceiver's  signal processing circuits to provide the 
>needed selectivity.   
>
>
>Spectrum analyzers and band scopes are essentially the same animal.  A 
>basic display is easy.  The hard part comes when you want precise sweep 
>linearity, exact amplitude calibration, and the ability to separate and 
>measure "close in" components of modulation products.  Those last items 
>are the reason that -hp- (Agilent), and other high end test equipment 
>manufacturers can command prices of $15K to $50K for their instruments.  
>For example, consider the measurement of a 1.2 GHz FM signal from a data 
>transceiver that I work on from time to time.  I happen to have a 
>Tektronix spectrum analyzer that will display discrete modulation 
>sidebands that are only 50 Hz apart, and measure their exact amplitude 
>and frequency offset from the main carrier.    It is however, rather 
>bigger than a breadbox,  and it costs a bit more than the SM-220.
>
>
>- Jim, KL7CC
>
>
>
>Radio Amateur N5GE wrote:
>> On Sun, 10 Oct 2010 13:58:20 -0800, Jim Wiley <jwiley at alaska.net>
>> wrote:
>>
>> Hello Jim.
>>
>> I have a Kenwood SM-230.  I wonder if the same holds true for that
>> model?
>>
>> Tom Childers, N5GE
>> Licensed since 1976
>> QCWA Life Member 35102
>>
>> n5ge at n5ge.com
>> http://www.n5ge.com
>> http://www.swotrc.net
>>
>>   
>>> Open up he SM-220.  The band-scope option is in a small metal box toward 
>>> the rear of the scope.   It will be marked either BS-8 or BS-5, for 8 
>>> MHz or 5 MHz respectively.  It may be possible to retune the unit to the 
>>> desired operating range, although it may be necessary to juggle some 
>>> component sizes.  A schematic can be obtained on line I think.  Note: if 
>>> it is a BS-5, the only difference between the units is the oscillator 
>>> coil and a few components.  Replacing the appropriate parts with those 
>>> for the alternate frequency range will make the switch.  Since these are 
>>> "discrete" parts, the swap should be straightforward.  The 8 MHz version 
>>> may have enough tuning range to shift over the K3 IF without changing 
>>> parts.  As supplied, the BS-8 is set for use with an 8.83 MHz IF, if I 
>>> remember correctly. The band-scope print is part of the main SM-220 
>>> manual. .
>>>
>>>
>>> - Jim, KL7CC
>>>
>>>
>>> DM4iM wrote:
>>>     
>>>> Elecrafters,
>>>> i like to interface a Kenwood SM220 Scope to a K3.
>>>> There is a Pan Display Option installed, but there is no hint
>>>> if it is the BS-5 (3.3Mhz IF) or BS-8 (8.83Mhz IF).
>>>> How can i determine which Pan Display i have?
>>>> I got this scope from a SK w/o any manuals.
>>>> If it is the 8Mhz IF, can i retune it AND will it work with a K3 /
>>>> KXV3A ?
>>>>
>>>>
>>>>   
>>>>       
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>>
>>
>>   