[GreenKeys] HAL ST-7000

[Bill Henry]

Hi Web,

The ST-7000 is a special modem I designed 10-15 years ago for use with 
AX.25 packet radio when guys were trying to use 300 bd packet on HF. This 
modem is a considerable improvement over other modems that were included in 
the TNC's of the time. But, 300 bd FSK and the AX25 protocol are very poor 
choices for use on HF radio.  The ST-7000 worked better but did not fix 
AX25 problems.  The "let's fix AX-25 for HF" problem evolved into CLOVER 
and then CLOVER-II and now CLOVER-2000, a protocol and waveform that IS 
optimized for HF use.  The ST-7000 has two FSK shifts - 200 Hz (packet 
"standard") and wide shift (425 Hz) that worked a lot better for 300 baud 
in my laboratory.  A few guys used wide shift but most stayed with 200 Hz 
shift to be compatible with the KAM's and PK-232's they talked to.  You 
might be able to use the ST-7000 on RTTY but you will need to redesign the 
filters to narrow them for 45 baud.  A curious feature is the U-bar tuning 
indicator.  In my opinion this was one of the best low cost indicators I 
designed. We did not use it on any other product but the idea led to the 
RTTY-1 which we still have.  That is no doubt a LOT more than you wanted to 
know but I don't get many chances to brag-up this unusual - and relatively 
unknown gadget.  Yes, we have manuals if you want one ($20).

Have fun,
Bill Henry, K9GWT

At 09:47 PM 3/3/2005 -0500, Web Williams wrote:
>Can't seem to locate a photo of this on the internet. Can
>anyone tell me exactly what this unit is capable of doing?
>
>Thanks, -KR4WM
>
>Kind regards, -Web Williams in Myrtle Beach, SC
>
>Echolink (ek-O lingk) n. 1. Just another AOL chatroom.
>2. A means to circumvent amateur radio licensing requirements
>using a computer connected to the internet. 3. A "pretend" radio.
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George W. (Bill) Henry          Internet: ghenry at halcomm.com
President                       WWW:      halcomm.com
HAL Communications Corp.        Phone:    217-367-7373
1201 W. Kenyon Rd.              FAX:      217-367-1701
Urbana, Illinois  61801
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