HF and 6M at the same time on a 6300, 6400(M) and 6500

Mike-VA3MW

Hi All

I wanted to share a little trick I have used in the past.

As you know, the 6300, 6400(M) and the 6500 only have 1 Spectral Capture Unit (SCU), so this only allows you to use 1 antenna at a time.  Unlike the 6600(M) and the 6700 which have 2 SCU's.

This can limit your 6M monitoring to having to use your HF antenna if you wanted to also monitor 6M and then switch to the 6M antenna when you need to.

There is a slick work around that allows you to use your HF antenna and your 6M antenna at the same time.  You would have 1 slice open on your HF frequency and another slice open on your 6M frequency.

If you add a Diplexor like the Comet CF-360B you can isolate the HF signals from each other so that your 6M signals (receive and transmit) go to the 6M antenna and those below 30Mhz go to the HF side.  Then you don't need to do any antenna switching as it is automatic since the diplexor contains high pass (6M) and low pass (HF) filters.

There is one caveat and that is you will not be able to use the internal antenna tuner on your radio since the Diplexor is 'in the way'.    If you need to use a tuner between the Diplexor and the antenna.

The Diplexor's are made by several manufacturers so you have a few options.  

In Comet's case, you want the B model since it has a common lead.   They also make an A model, and you can make that work but the leads are different and you'll have to add some adapters to make it play.   The B model gives you the common lead that connects directly to the radio.



HF/6M - 440MHz Duplexer with common lead

Band Pass Ins Loss Max Power

1.3-30MHz 0.2dB 600W PEP

49-470MHz 0.2dB 600W PEP

Isolation: 45dB minimum

 
CONNECTORS:

Common: PL-259

Low Pass: SO-239

High Pass: SO-239


Here is a rough idea on how to set it up with the HF antenna (model) on the left and the 6M on the right.  



73 for now, Mike 

Andy W3LI

You read my mind on this. I have been using the Comet CF-360 as you have it. However, I added a MFJ 1702C band switch in the line so that I can bypass the Duplexer and put my 7 el 6M beam on line. Works good that way.
Hope all is well with you. Stay safe and healthy.
Andy... W3LI

WK2Y

Love it!!  Give that man a raise!!

KD0RC

Great idea! The thing to watch out for is that the Flex antenna gain/atten is per SCU. So if you want 0 dB on 80 and 32 dB on 6, you have to remember to switch back and forth. Not a big problem if you are just looking for a band opening, just something to be aware of. 73, Len, KD0RC

Mike-VA3MW

Good point.  You could set up a few Global Profiles to quickly switch things around once you get them dialed in.

KD0RC

I do tend to mess with the RF gain a lot (especially on the lower bands) as my noise level goes up and down dramatically during the course of a day. I try to keep the RX in that 8 - 10 dB sweet spot (ant vs. no ant). So for me, adjusting the RF gain/atten and the AGC-T is no big deal. I do wish the AGC-T setting was visible as a thin horizontal line on the spectral display. It would be much quicker and easier to set... Len

Howard AE3T

Darn! I had one for years and sold it last year when I changed cars and sold my HF/VHF mobile rig. Should have kept the duplexer for some future use!