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SJC EMCOMM Freqs
SJC1 - 147.210 + 114.8 Stockton (Stockton Pri)
SJC2 - 146.655 - 100.0 Tracy (County Pri)
SJC3 - 145.210 - 100.0 Tracy (County B/up)
SJC4 - 147.090 + 114.8 Lodi (North Pri)
SJC5 - 146.985 - 100.0 Manteca
SJC6 - 147.165 + 107.2 SDARC
SJC7 - 147.015 + 114.8 Copperopolis
SJC8 - 147.105 + 94.8 Stockton
SJC9 - 146.895 - 114.8 Mt. Oso - Disabled
SJC10 - 444.400 + 114.8 Copperopolis
SJC11 - 444.325 + 94.8 Stockton (Stockton Pri)
SJC12 - 443.825 + 107.2 Mt. Oso
SJC13 - 444.575 + 107.2 Stockton
SJC14 - 444.850 + 114.8 127.3 Tracy 
SJC15 - 444.500 + 114.8 Stockton
LLNL - 146.775 - 100.0 Livermore


TAC1 - 146.550

TAC3 - 146.535
TAC4 - 146.430
TAC6 - 156.565
TAC7 - 146.595
TAC8 - 146.445
All simplex
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N5FDL/CEVOL Repeaters

Stockton: 147.210 + N5FDL and 444.500 + K6TRK Both PL 114.8 (linked)

Copperopolis/Gopher Ridge: 147.015 + and 444.400 +  (not linked) N6GKJ 

Mt. Oso: 146.895 - N5FDL and 443.825 + PL 107.2 (not linked)

Tracy: 444.850 + KB6EMK PL 127.3

Affiliated Repeaters

Bear Mtn.: 146.090 + and 444.250 + WB6ASU Both PL 114.8 (linked)

Mt. Delux: 145.210 - PL 100.0 WA6SEK (10mi S of Tracy)

All repeaters are open to all users.

« Open Letter to "Atomic" Clock Vendors | Main | The Battery Case I've Been Looking For? »
Friday
Oct242008

At Last: A Memory Upgrade for KPC-3+

The Kantronics KPC-3+ TNC is a great radio modem, except for one thing: The base unit comes with 128 KB RAM and that’s not enough to run a multiuser mailbox, as you might want to do in an emergency operation.

Kantronics used to offer a 512 KB upgrade, but it hasn’t been available for several years because the company was unable to purchase the part.

Several weeks ago, I posted a question on the Northern California Packet Association mailing list, wondering if anyone knew of an alternative to the memory Kan’tronics is unable to supply—the last alternative I found cost almost $200 and it, too, is also no longer available.

The reason I wanted the upgrade was because Jim Oberhofer, KN6PE, has written a wonderful emergency packet client called OutpostPM that is capable of using a KPC-3+ as its mailbox. This would allow a KPC-3+ to serve a reasonably-sized emergency network when nothing else was available.

But, a KPC-3+ with 128 KB RAM provides only about 90 KB of mail storage. If each message takes 4K, then you get 22 messages in the mail system at any one time. Taking the memory up to 512 KB leaves…well, I’ll pass you over to a happy message that KN6PE posted to the NCPA remailer last week:

Hello,
Well, this caught my attention since I was also looking for the memory upgrade. From an EM point of view, a KPC-3Plus with its ability to support concurrent PBBS connects and 512Kb of memory can be used as an emergency “BBS-in-a-box”. A couple of folks in Santa Clara County have done just that… but the lack of a memory upgrade is limiting.

I have 3 KPC3s at home w/ FW versions 5.0, 5.3, and 8.2. The 8.2 is the KPC3P and comes with the latest PC board. With the hints from the folks below, I found and ordered an SRAM 512Kbx8 chip from Jameco.com (Digikey also has equivalents). Jameco’s catalog page listed it as follows:

Catalog No=157358
CrossRef=628512LP-70
Package=DIP-32
Config=512K x 8
Description=4Mbit, 5 V, 70ns, LP
Price=$19.19 + ~$7 shipping (shipped out of Belmont CA)

Comparing the data sheets of this one and the installed 128K memory module did confirm this is pin compatible with the original mem module.

This upgrade works fine on the KPC3P. There is a jumper change that you need to make (J14: from Pin1/Center to Pin2/Center). The TNC executes its autobaud routine on power up, and the PBBS command shows 480 (480Kb of mailbox space available). This is confirmed when connecting to it and seeing the PBBS welcome message. The KPC3P manual covers all of this.

Search the .pdf for “J14” to quickly to get to the part in the manual.

Unfortunately, this upgrade does not work on the older KPC3s (been there, tried that).

Next steps: beat up the PBBS by loading it up with messages to confirm there aren’t any funny timing problems.

Hope this helps.

Regards,
Jim o KN6PE

I am in the process of installing potentially a few high-level nodes, but won’t do it until I can make a drive over to Belmont. I’ve wanted to visit Jameco for a while and now have a good reason to stop by next time I am on the Peninsula.

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