[GreenKeys] Terminal unit (HAL ST-5000) adjustment

[Jeffrey Angus]

On 1/8/18 8:24 PM, Ethan Blanton wrote:
> * Some of the signal troubles I had on the band may have been
> due to commercial TU 200 Hz shifts, which I hadn't considered.
Both the AEA PK-232 and the Kantronics KAM used 200 Hz shift
for RTTY. It wasn't right then, and it still isn't right.
> Several people were concerned about the 2-B IF bandwidth and its
> affect on alignment, but I assure you that I did not try to align
> the unit through the 2-B.  :-)  I used known good tones at a
> controllable amplitude for that!
On bandwidth.
A simple on/off keying at 60 WPM requires about 320 Hz
bandwidth. This is to allow the 7th harmonics of the baud rate so
that the keyed signal looks like a square wave.
If you use FSK at 170 Hz, this increases the bandwidth requirement
to 320 + 170 or 490 Hz.
A side note to this: The 170 Hz shift was picked so to minimize the
amount of that 320 Hz sideband power in the other tone's response.

Part of proper receive tuning of the 2B includes putting the passband
tuning outside of the ._. markers.

-- 
"I am a river to my people."
Jeff-1.0
WA6FWI
www.foxsmercantile.com