[GreenKeys] Scope vs Lavoris

[Lawless, Loveless & Childress]

>>> That post-processes the channel signals for a pretty display, but its not showing you what the TU is actually doing.

Now THERE was a mouthful! 

I started to reply, to the original query, to turn the Intensity on the scope trace down until the display was dark, then tune the signal by ear until it prints.

Then, tune UP until good copy lost.

Next, tune DOWN until good copy is lost.

Once that's done, turn the trace back on, repeat, and watch the impact upon the scope display.

The scope will tell you if the other fellow's shift is right; it will tell you if he is "upside down" (although the Mark One human brain connected to the Highly Evolved Human Ear will do as well); if his tones are relatively distortion-free; and if he has any audio "transients" or artifacts of tone generation occurring in the passband of your receiver and how aggravated they may be. And, if he's using a mechanical printer, a bit about the state of his gear that even he might not know.

And, yes, toroid filter components will yield crossed ellipses (or bananas, or footballs). Op Amp filters (1458's in the Fleshers) will give you crosses.

What does the shape of the display picture do for your ability to print signals?

Zip. As long as the other guy's tones are shifting between 162 and 177Hz, the Flesher circuit will do a better job of rejecting some QRM near-frequency than the ST-6 (and as good as the -6000). This is a function of the Q of the filters and the dynamic range of the Limiters. 

When the signal strengths decline to the point that your receiver's audio no longer drives the ST-6 into "limiting" and you are into "limiterless" mode, the ST-6 and its younger brothers outshine the Flesher. (The "Slicer" in the Hoff circuit is a Thing of Beauty!) 

But NOT by an order of magnitude. I use the Flesher external/added audio filter circuit board ahead of the DM-170 card, giving several more stages of op amp filtering.

Own both HAL ST-6000 (HAL-built) and a DM-170 and AFSK generator integrated into an old Drake 4-Line speaker cabinet. Use both here and have since 1978, adding the P-38 card in 1996.

(The HAL P-38 and its successors put most everything except the ST-8000 and some Thrane and Thrane gear I used professionally to shame...even better than the Frederick we all seem to love irrationally. The problem nowdays becomes: Where is the ISA slot in YOUR computer?)

IMHO, the scope is the biggest "Tennessee Go-Fast" device in the RTTY shack until you know what you're looking at. The meter on the ST-5's and -6's, the IRL and the Flesher TU-170  is/was more than sufficient for users with Beginning through Intermediate skill levels. I only have one now because the ST-6000 already had it installed. It tells me little that my ears don't.

If you can't identify 170 vs 850 shift, or discern the distinct sound of a lime of RY's (or 46's, if your USOS is OFF) or make an educated guess that a particular group of sounds is a QBF tape, then your scope is just warming the air up in your shack.

Once you CAN do the above, the scope can be useful.

Just my opinion from 36 years of FSK, on the ham bands and afloat...

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