630 MHz transmit and receive using the K3S or a modified K3


Here’s some info to get you started on 630 meters with the K3S or K3. For receive purposes, either transceiver is fully self-contained. For transmit, you’ll need an external amp of some kind.


The K3S, or a modified K3, will receive on this band via the XVTR IN jack (or RX ANT IN). You’ll need:

- A KXV3 transverter interface module (standard with the K3S but optional for the K3)

- A KBPF3A filter module, or a KBPF3 with a small mod (see KBPF3MDKT). The KBPF3A mod kit also comes with a capacitor to be installed on the K3’s RF board to suppress LF noise.

RX performance is quite good on 630 meters.

Note: The XVTR IN and RX ANT IN jacks work on 630 meters (472 kHz) because both are post-TR switch. The TR switch has high-pass filtering that rolls off starting around 1 MHz, so you can’t use ANT 1 or ANT 2.


You can get a transmit signal out on 630 meters using the XVTR OUT jack (same requirements as above). Our initial tests shows about 0.5 milliwatts. In this case you’d use XVTR IN for receive, not RX ANT IN.

You’ll then need an external amplifier. It could be keyed using the rig’s KEY OUT jack. This signal could also be used to control a T/R switch if you needed to use the same antenna for both transmit and receive. If you use two different antennas, you’ll still have to cut the RX antenna off during TX, most likely.

Firmware configuration:

To use XVTR IN and OUT on this band, set up the radio for 160 meters, then set the CONFIG:KXV3 menu entry to TEST. This is necessary because 160 meter isn’t available as a transverter IF selection (yet).


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