I happen to own both the TS-850SAT/DSP-100 combo and a TS-950SDX. Note however that I've only had the latter radio for a couple of weeks, so you might take what I say with a grain of salt.
In general, I much prefer the TS-950SDX. Both have great voodoo audio, but for my money the 950 just has a more comfortable feel. Some comparisson points:
- Both radios have the same, very quick internal tuner
- Both radios have an IF OUT interface for the SM-230 station monitor
- The TS-950SDX comes with the SO-2 TXCO built in. You can add the SO-2 to the TS-850 as an option (I did), but you have to track one down and it's extra work.
- The TS-850 uses an LCD display while the TS-950SDX uses a florescent tube display. The latter has the advantage that it's visible at all angles, but the display on the TS-850 is sharper, which I prefer.
- Out of the box, I think the TS-850's receiver has a little wider audio response compared to the TS-950SDX. You can of course perform dem voodoo modz on the TS-950SDX to vastly improve it, but the work is not for the timid.
- Out of the box, the monitor on the TS-850 has better response as well. Again, you can improve this if you do the full set of voodoo mods to the TS-950SDX.
- While the TS-850's monitor has better out of the box fidelity, it only works in SSB voice modes; the TS-950SDX's monitor works in AM and FM too.
- While I can get my computer to talk to the TS-850 using a direct connection to the ACC1 port on the back of the radio, I've never gotten it to work via the CONT OUT port on the DSP-100 (which you must use because the DSP unit takes over the ACC1 port when it's connected). I don't have any problems communicating with the TS-950SDX.
- Voodoo audio bandwidth on the TS-950SDX is a little wider on than on the TS-850SAT/DSP-100 (6.7Khz vs 6Khz)
- You can trick both radios into producing DSP-modulated voodoo audio on AM, but to my ear the TS-950SDX sounds much better than the TS-850SAT/DSP-100 when you do it. You can achieve excellent AM fidelity with the TS-850 by injecting audio directly into the balanced modulator, but this requires additional modification.
- Both radios allow you to turn the extended TX voodoo audio bandwidth on and off at will. However, with the TS-850SAT/DSP-100, you need to use dip switches on the back of the DSP-100 unit in order to set the low cut and high cut filters to the "off" position, whereas with the TS-950SDX you can configure everything using menu options. I find the latter much more convenient.
- With the TS-850SAT/DSP-100 combo, there's only one set of DSP bandwidth control knobs, which affect both RX and TX. With the TS-950SDX, you can set the RX DSP bandwidth separately (menu option 22) from the TX bandwidth (menu options 20 and 21).
- The TS-850 seems a little easier to operate at first compared to the TS-950SDX, largely due to the menu functions. However, most of the menu settings only need to be configured once and then you can pretty much forget about them. Both radios are fairly intuitive once you get the hang of them.
- For the TS-950SDX, you'll probably want the latest firmware. If you can only find an older radio, don't despair: you can still get the latest firmware into it. Although Kenwood no longer had replacement chips available, there's at least one source selling chips with the latest firmware release online. Or, if you're lucky enough to have access to an EPROM programmer, you can make your own. (See:
http://people.freebsd.org/~wpaul/ts-950sdx/firmware for instructions and a copy of the firmware image.)
The DSP-100 has two knobs on the front that control TX audio bandwidth, and normally the widest you can set it is for 3Khz (100hz low cut and 3100hz high cut). To get voodoo audio out of the TS-850SAT/DSP-100 combo, you need to turn off switches 1, 6 and 7 on the back of the DSP-100, and set service menu option 1 to 'on' to allow you to operate the 8.83Mhz and 455Khz filter selection controls during transmit as well as receive. Once you set the 8.83Mhz analog filter setting to bypass (all filters off), you'll get 6Khz wide audio. After you change the switch settings, the bandwidth control knobs on the DSP-100 are disabled. You can control the TX bandwidth using the 8.83Mhz analog filter control. However you only get 3 settings: 6Khz, 4.5Khz and 2.7Khz.
With the TS-950SDX, you can control the low and high cut TX bandwidth using menu options 20 and 21. Our of the box, the low cut option can be set to "off" but the high cut can't. To get voodoo audio, you need to use the power-on menu to enable selection of the analog filters during transmit (same as the TS-850), and then you also have to hold the FINE button on the front panel down in order to enable the "off" selection of the high cut menu option. Set both the low and high cut menu options to "off" and then set the 8.83Mhz TX analog filter to the bypass position, and you'll be transmitting with 6.7Kc bandwidth.
Note: if you turn the TS-950SDX's speech processor on, the high cut setting is forced to a fixed setting regardless of how you've got things configured. The LPF menu option display indicates "Proc on" and the audio response is limited to 3Khz. The low cut filter setting is unaffected.
In both cases, the recommended course of action to achieve the best possible TX fidelity is to inject audio directly into the DSP from the audio rack using a Jensen transformer. In the case of the TS-850SAT/DSP-100 combo, the mod is done to the DSP unit. In both cases, you have to drill a hole to mount a jack for the external audio input. This avoids any high or low frequency roll-off or distortion that might be induced by the mic preamp circuits. In my opinion, this mod is for serious voodoo fanatics: you can still get excellent audio from both radios if you just use the front panel mic jack. For the TS-950SDX, there's a middle ground where you can supply the audio via the ACC2 port to bypass the mic preamp, if you're willing to change out a couple of capacitors.
The nice thing about the TS-950SDX though is that if you want to turn off the voodoo sound, all you have to do is change the TX bandwidth menu options to something less wide. Most of the time I leave the radio set to 3Khz on SSB. For some extra punch for DX, you can set the low cut filter to 200Hz and turn on the speech processor.
I wasn't very happy with the speech processor on the TS-850, and like I said, you need to flip the switches on the back of the DSP-100 in order to switch out of voodoo mode and re-enable the high/low cut controls.
On the whole, I would say the TS-950SDX is a better all around radio. It's a little more flexible, has better voodoo potential, and added bells and whistles. Also, I think the TS-950SDX may be a little easier to acquire. I see TS-850SATs come up for sale fairly frequently, but the DSP-100 unit is another matter. Those are pretty rare, and the prices are often high. If you can find a TS-950SDX from late in the production cycle, I would jump on it.
-Bill