[FADCA] TNC built into radios

[bud thompson]

NOTE: Subject changed from Re: [FADCA] Interesting Note


----- Original Message ----- 
From: "Chuck Hast" <wchast at gmail.com>
To: "FADCA" <fadca at mailman.qth.net>
Sent: Sunday, December 19, 2004 23:02
Subject: [FADCA] Interesting Note


> We discovered that the Kenwood D-7 series embedded TNC will not pass
> non-pid f0 packets at the hamfest the other day, we tried to use the D-7
> which I have in my van as a digi to get to Tampa (we were able to hit
> the tampa switch just fine from my van, so I set the portaswitch up to 
> digi
> via the van back to tampa, no joy. At first we thought it was a timing 
> issue
> because it kept on doing a rr on the frame previous to the level 3 frame,
> but when I went to the van and started looking at the link from the 
> vantage
> point of the digi, I realized that the digi was not passing the pid 01 
> (ROSE
> level 3 stuff) frames. I did not realize that digi's even looked at the 
> PID in
> a Ax25 frame as long as the frame was ax25. So if you are going to use
> a Kenwood with the embedded radio as a digi to digipeat  level 3 stuff
> don't waste your time.
>
> That puts Kenwood even lower on my list of data radios, in truth the TNC's
> for those radios were more designed for the APRS crowd than anything
> else, they do APRs pretty well, but are a bit stupid when it comes to 
> regular
> packet.
>
> Here is another bit of stupidity, the kenwood people in their infinite 
> wisdom
> have chosen to drop the ax25 ver 2, it is only running ver 1 in the TNC 
> soooo...
> If the far end sends a DISC frame your end will send a UA confirming the 
> discon-
> nect. BUT if the far end does not hear the UA come back it will send a
> DISC again,
> the disconnected TNC should send a DM saying I AM disconnected, shut up 
> and
> go away, but it does not, it sets there and sends NOTHING, so the far end 
> sends
> whatever it's retry count is of DISC frames until it times out. Don't
> you just love
> spectrum pollution like that? I will give them one good set of points
> the 9k6 modem
> and radio part work pretty well though the radio still needs about it 
> seems like
> 100ms to get things in the right state in order to send or receive data.
>
> Indeed it appears that connected mode was sort of a after thought, too
> bad because
> the radio is a pretty good box for packet. Sure wish there was a
> simple way to put
> in a different eprom, but I think it is all surface mount....
>
>
> -- 
> Chuck Hast

* * *


It's not Kenwood - it's the Tasco on-chip  TNC made for APRS that all the 
'with TNC' ham radios are using including the Kenwood TS 2000 and other big 
boys.

These TNCs should only be used for testing and are not suitable for 
message/file transfers.  It has to do with the internal buffer size - they 
can't stop taking data from a terminal program and overflow.

I can dig up more specifics if you like, but we gave up on these built-in 
Tasco TNCs in April or May this year after learning the radios won't support 
Paclink AGW (or any file transfers) w/o a real TNC.

bud N0IA