Just a few minutes ago I had a really nice chat with Lloyd Alcorn, one of the three founders of Wacom Products. Lloyd's background includes being a professional engineer working for Decibel Products and helped design the DB 222 folded dipole antenna. Lloyd Alcorn, Larry Bush (W5NCD) and Kit Parsons (deceased) founded Wacom Products and for many years Wacom existed in a couple of service bays at Waco Communications, an RCC and Land Mobile shop in Waco. I worked for Waco Communications from 1975 thru 1981 in the RCC end of things but had much contact with the Wacom folks even after I went into business for myself in 1985.
According to Lloyd, the cable length between a duplexer and an inline cavity filter and the receiver makes little or no difference. The culprit to beware of is - radiation from the receiver toward the inline cavity filter. The LO is the primary source of this radiation, but there may also be other signals generated by the receiver. This low level signal sets up standing waves between the receiver and the cavity filter and may cause some black magic to enter into the equation. Changing the cable length may help reduce the effects of stray radiation between the receiver and the cavity should this occur. Placing a band pass cavity between the receiver and the duplexer will make no difference at all if the interfering signal is on the receive frequency. Now the transmitter. Again most but not all of the time, the cable length between the transmitter and the duplexer will make no difference, EXCEPT that the transmitter may have other out of band energy that again sets up standing waves between the transmitter and the duplexer and these unwanted signals bounce back and forward between the transmitter PA and the duplexer and intensify. This is where a magic cable length can help. Also an isolator can help not withstanding the isolator does create it's own set of problems. Lloyd still lives and Waco. I promised NOT to give his phone number and he said he is not in hiding. He is still very active, golfing from time to time and serving in the Baptist Church there in Waco. His health is good, except for the standard maladies of getting older. He did mention that Kit's demise came quickly, having talked with Kit some months earlier and Kit made no mention of an illness. Lloyd gives his best regards to all the folks he worked with over the years - said when they get up in the morning, sometime they go back to bed - don't have to go to work. Best 73, Steve NU5D -- Ham Radio Spoken Here !!! NU5D EM11 http://www.qrz.com/callsign/NU5D Nickel Under 5 Dollars
