DCD improvement for the TAPR TNC-2 The following message appeared on the TAPR netsig list in 1995. It represents a very simple modification to a TNC-2 or clone (e.g., MFJ-1270B) which will greatly improve the open squelch characteristics of the TNC for FM AFSK use with much less complexity than the TAPR DCD MOD kit (which is needed for HF operation and also works for AFSK). Re: [NETSIG:899] Re: DCD mods? _________________________________________________________________ * To: netsig@tapr.org * Subject: Re: [NETSIG:899] Re: DCD mods? * From: Jack Taylor * Date: Sun, 5 Feb 95 20:03:05 MST _________________________________________________________________ The original N7CL DCD modification to the TNC-2 for VHF consisted of only 3 parts, two 180k 1/4 watt resistors and one .01 50v disc capacitor. One resistor replaced R73. The capacitor is paralleled by the remaining 180K resistor and this network is connected between pins 3 and 6 on the underside of U20. The DCD modification for HF is somewhat more complex. 73 de Jack