I've used the loop and a KD9SV preamp with the vertical before, JC, and no overload problems ...I run QRP power during Top Band contests. Your cautionary notes are noted and appreciated! Jim R. K9JWV
> From: [email protected] > To: [email protected]; [email protected] > Date: Mon, 13 Jan 2014 11:33:21 -0500 > Subject: Re: Topband: Single antenna port xcvr but want to employ > separate receive antenna > > Hi James > > There are several solutions for a separated receive port. However let me > comment on some details, > > 1- Small Delta loop. To be a receiver antenna the antenna gain need to be > less than 20 db, why ? simple. Connect a power meter and a 50 ohms load on > the Small Delta loop and measure how much power is captured from the TX > antenna, I know several guy the burn the RX port on ICOM and YAESU radios > using transmit antennas as receiver and injecting 100W into the RX port when > transmitting with a legal limit amplifier. Port isolation and RF protection > must be the first concern for any solution. If the antenna used for RX is > resonant on the same TX band , you can really burn you RX front end. > > 2- Switch speed. The receive port need to switch fast than TX port. 20ms is > not enough, most small frame relays switch around 20ms , To play safe it is > necessary < 10 ms. Another thing to consider. > > 3- The RX antenna only will add some SN if it adds some directivity, > otherwise the attenuator at -20db will do the same job. > > 4- Isolation, on low bands if you have s9+10db noise and only 50 db > isolation between the RX and TX port, the signal from the TX antenna will be > add to you RX signal degrading the signal to noise and reducing side and > back nulls form the RX antenna. > > I can list another several reason to the subject but the T/R switch is a > very important part of the receiver system if you want to have some > improvement on the signal noise. > I sent one RTR-1 to T6LG to use with a good Preamp from KD9SV and a Delta > Flag antenna using twisted pair. Without the RTR-1 the system would not > perform well as it did. > > Just my two cents. > > Regards > JC > N4IS > > -----Original Message----- > From: Topband [mailto:[email protected]] On Behalf Of James > Rodenkirch > Sent: Monday, January 13, 2014 8:36 AM > To: Top Band Contesting > Subject: Topband: Single antenna port xcvr but want to employ separate > receive antenna > > Have my vertical working great and have a small Delta-loop low band receive > antenna BUT the Ten Tec Jupiter doesn't have a separate receive antenna like > a K2, for instance (I borrowed a K2 to try out but the buttons/controls are > to small for me to operate as I have a severe case of peripheral neuropathy, > courtesy of Agent Orange).So, I am up and running and will be in the CQ 160 > contest at the end of January but have no means, currently, of switching > rapidly 'tween the top loaded vertical and loop. A T/R switch won't "do it" > for me....so looking at a DX Engineering RTR-1A but sure don't like the > price!!http://www.dxengineering.com/parts/dxe-rtr-1a > Anyone have an RTR-1 or 1A that is excess to their needs and willing to sell > OR have another idea of how I can employ a separate receive antenna when I > have one antenna port? > Thank you, in advance, for any replies....off line replies work for me. > 72/73, Jim Rodenkirch K9JWV > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
