MF/LF OPERATING: Life Below the AM Broadcast Band
Plus … Heavy Lifting at W7XU, a Remote Operation in England Results in Many QSOs with North America, and KB5NJD says 73
Over the last few years that I have given presentations on the topic of 630 and 2200 meters, I have encountered a surprising number of amateurs who are unaware of the common practice of using separate transmit and receive antennas (about 79% of attendees). Along the same train of thought, how both of those antennas might connect to a transceiver at the same time is often at the top of the list of questions encountered.
Interfacing a receive-only antenna to a transceiver usually comes in one of two ways. In the first case (Figure 1), the transceiver has a separate receive antenna input and there is probably a button on the front panel to engage this antenna when the radio is in receive mode. All switching is internal and automatic when changing state from transmit to receive and vice versa. This approach is most common with physically larger transceivers that are often found in the higher price category, although this may be changing with some of the higher performance, subcompact transceivers coming to market today.
The other approach () requires the amateur to use the traditional RF transmit/receive antenna port, often an SO-239 connector, joined to some type of relay box with two RF connector inputs and controlled by the transmit line often used to control an amplifier’s transmit and receive state. One of the RF inputs is used for the transmit antenna and the other for the receive antenna. This type of relay box can be as simple
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