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[aprssig] Re: High density timeslotting

Stephen H. Smith wa8lmf2 at aol.com
Fri Jun 9 04:25:53 UTC 2006

scott at opentrac.org wrote:
> Digipeating would present an interesting challenge.  Obviously if the
> channel utilization is over 50%, you can't digipeat in-channel.  Are there
> any dual-port TNCs out there that can handle full duplex digipeating, 
The limitation on full-duplex digipeating is normally the radio, not the 
TNC.  Nearly any ( even single-port) TNC can do this if you connect the 
input to one radio's receiver and it's audio output and PTT lines to 
another radio on another band.  I have even done this in-band by 
connecting the TNC RX of a garden-variety TNC2 (MFJ-1270) to the 
receiver of a repeater and the TNC TX to the transmitter of the same 
repeater.   (You interrupt the normal carrier-operated audio and PTT 
path between the RX and TX -- the repeater operates more like a 
full-duplex base station.)  A  Kenwood D700 with one side set on VHF, 
the other side on UHF and the TNC menu set to RX-A/TX-B  could even do this.

> and
> what transmitters would be suitable for 100% transmit duty cycle for
> cross-band operation?
Any, as long as it is adequately cooled (or the TX power is reduced well 
below max output).     Again, a D700 on low power (5-10 watts) can 
transmit essentially forever. I've run my Kenwood TM-211 and and TM-221  
2M monobanders (rated as 25W in high power mode) at  10 watts 
continuously keydown for several hours at a time. 


Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      14400    [Think bottom of the 2M band]
Home Page:          http://wa8lmf.com

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