---------------------------------------------------------- Avionics-List Digest Archive --- Total Messages Posted Fri 06/18/04: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:15 AM - Fw: vexing comm problem (John Rippengal) 2. 03:10 PM - Re: KX-155 & transmit interlock (Mike) ________________________________ Message 1 _____________________________________ Time: 04:15:01 AM PST US From: "John Rippengal" Subject: Fw: Avionics-List: vexing comm problem --> Avionics-List message posted by: "John Rippengal" > If you mount the antenna in that position then you are really just asking > for trouble. The pick up from the transmission will be several volts of RF > and with any minor non-linearity (eg a transistor, diode or even a switch > contact) rectification can take place. This can feed into the audio ccts or > even the PTT and cause feedback howls or the low frequency 'machine gun ' > effect. > The proper solution is to remove the antenna to for example near the tail or > in the tail. You will get better communications and less feedback. You can > also fiddle about with ferrites on the audio wiring including headsets cable > etc and you might cure it. But it's like complaining that your ice cream > melts in a furnace. > John Rippengal > > > From: > > ..................................... > > > > > 2) Engine run up complete, switch to tower (133.1), try to talk using same > arrangement as in 1). The result is a machine gun like sound when I key the > transmitter -- impossible to transmit coherently. (Rapid intermittent making > and breaking of ground contact for PTT?). Receiver works OK. > ................................................................ > > > > VHF comm antenna is a Bob Archer antenna mounted inside the fuselage side > aft of the copilot's seat. > > > > Any thoughts? Thanks for your help. > > > > > > 'OC' Baker, Builder of KIS TR-1 #116 4/14/97 - 11/17/03 > ________________________________ Message 2 _____________________________________ Time: 03:10:31 PM PST US From: "Mike" Subject: Re: Avionics-List: KX-155 & transmit interlock --> Avionics-List message posted by: "Mike" I thought it had one but I can't find it on the wiring diagram either... Mike ----- Original Message ----- From: "Jim S" Subject: Avionics-List: KX-155 & transmit interlock > --> Avionics-List message posted by: Jim S > > I am installing dual KX-155's and find no pin identified as a 'transmit interlock' in the schematics. Am I missing something? I do see pin 14 on the Garmin 430 schematic. Is this option available on the KX-155? Thanks. > > Jim