Using the VHF port for 6m on an Icom IC-706mkIIg transceiver

Question

My Icom IC-706mkIIg transceiver has two output ports:

• one for its VHF/UHF bands (i.e. 2m/70cm)
• one for the HF bands, and also 6m!

I have a couple of broadband VHF/UHF antennas whose transmit specs include the 6m (50MHz) band, so I'd rather have the 6m band output on the VHF/UHF port. I understand for example that the Yaesu FT-817ND allows some configuration of which bands use which of its two ports, but do not see anything similar in my Icom's menu settings.

Is there any modification available to move 6m handling to the IC-706mk2g's VHF port, whether a setting I've missed, a jumper inside, or even some minor circuitry rework?

Otherwise could I accomplish this without undue loss — or expense! — via some combination of diplexers and/or other filters?

Answer 1

If you don't find a solution based on modifying the radio, this is a reasonable use for two diplexers. You can, in principle, hook them up two different ways:

^{simulate this circuit – Schematic created using CircuitLab}

These two configurations have in theory the same requirements for the two diplexers — one which separates 30− and 50+ MHz and one which separates 54− and 144+ MHz. However, the second configuration has two advantages:

• It should have less insertion loss at other than 50 MHz, since the other bands pass through only one diplexer and not two.
• The bottom left diplexer deals only with frequencies 54 MHz and below, — it does not need to have good performance at UHF.

A brief search (I didn't check all the specifications in detail) shows that suitable duplexers are available from several brands (Comet, Diamond and MFJ) for prices around US $60-80 each.