We had the same kind of troubles in NYC with Maxtracs, switched to Micor Spectra-Tac receivers and the problems went away. The Maxtrac is great for a mobile, or in a quiet location, but you need a "real" receiver with shielding, and a helical front end in high RF locations. Lance N2HBA ----- Original Message ----- From: Chuck Kelsey To: [email protected] Sent: Thursday, November 22, 2007 11:36 AM Subject: Re: [Repeater-Builder] Receiver overload
I agree with Eric about the shielded enclosure especially. And be sure to use a connector on the coax where it passes through the box. Just running the coax through a hole in the box defeats all, most or some the shielding of the box. Chuck WB2EDV ----- Original Message ----- From: "Eric Lemmon" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, November 22, 2007 11:10 AM Subject: RE: [Repeater-Builder] Receiver overload > David, > > My first move would be to add a bandpass cavity in front of the receiver. > All cabling between the receiver and the RX output of the duplexer should > be > double-shielded, with proper connectors on each end- no adapters, and no > nickel-plated connectors. The mini-UHF connector going to the MaxTrac > should be the only exception, but it's okay if very tight. > > If that doesn't cure the problem, then enclose the receiver in a shielded > box, and bring the signal and power leads out through feedthrough > capacitors. The MaxTrac radio has a lot of plastic in its case, and is > susceptible to signal intrusion. The best shielded box to use is a > die-cast > aluminum enclosure from Hammond. > > I have assumed that the FM transmitter carrier is pure, without harmonics > or > spurious artifacts. If the FM transmitter is radiating on a frequency > close > to your desired input frequency, the above fixes may not have any effect. > > 73, Eric Lemmon WB6FLY > >
