Diplexer choices

[kh2]

Confused at the diplexer choices available. Simple situation I have an IC-705 with an AH-705 tuner, and would like a diplexer for HF and UHF / VHF to tidy up the antenna wiring. Mostly run UHF / VHF on repeaters and HF voice to digital 6m-80m (160m - not yet)

Would like the diplexer it to go above 100w to future proof the possibility of an amplifier

I'm not married to any brand just looking for the best to the job. My searches have landed on Comet but I see models - CF- 360, 530 and 706. They have differing cut off points and not sure how that affects my set up. And I know just enough to screw up the simple solution.

Any input would be appreciated - Thanks!

 

[K4EET]

If you want to run up to 600 watts RF, then this is the one that you want:

Comet Duplexers CF-530​

Low Pass Frequency Coverage:
1.3-90 MHz
High Pass Frequency Coverage:
125-470 MHz

As for better ones, what is your budget?

 

[K4EET]

<snip> I have an IC-705 with an AH-705 tuner <snip>

Of course the antenna tuner is only good for up to 10 watts. You’ll need another antenna tuner for 600 watts if you go QRO.

 

[kh2]

Thanks - understood on the antenna tuner. I guess budget depends on the return value. but if the value was there I could see doubling the price of the comet. I'd hate to sell my vacation home and Porsches. ok maybe I'd let one Porsche go...

 

[K4EET]

What arrangement is your system? It looks like the Icom IC-705 only has one RF connector. Is that correct? The radio switches between HF and VHF/UHF using the same BNC connector? Are you using two antennas, one for HF and one for VHF/UHF? The antenna tuner is bypassed when operating VHF/UHF? Sorry, I’m not familiar with the rig and just looked at the basic manual. Trying to understand how you’re envisioning this system.

 

[kh2]

yes one BNC connector to the radio. the Radio switches using the one BNC connector. I do have 2 antennas a random wire and an Elk Log periodic for UHF / VHF. And yes the tuner is bypassed when using UHF / VHF. So for me the BNC to appropriate adapter to the diplexer than fed out one to the HF / tuner / random wire and the second to the Elk. just avoiding swapping antenna wires without a switch.

Once my antenna farm grows I will probable use a remote switch.

 

[K4EET]

yes one BNC connector to the radio. the Radio switches using the one BNC connector. I do have 2 antennas a random wire and an Elk Log periodic for UHF / VHF. And yes the tuner is bypassed when using UHF / VHF. So for me the BNC to appropriate adapter to the diplexer than fed out one to the HF / tuner / random wire and the second to the Elk. just avoiding swapping antenna wires without a switch.

Once my antenna farm grows I will probable use a remote switch.

What I am now concerned about is whether the Comet device is a duplexer (splits signal based on direction) or a diplexer (splits signal based on frequency). Comet calls the device a duplexer which is used to tie multiple radios to a single antenna. You may want to consult with Comet and see if their device is truly a duplexer.

 

[kh2]

Good points - it is labeled as a duplexer and I did not mention it in my OP to save the diplexer/duplexer discussions. The Comet has been recommended on 705 forums by other users. my hesitation was the cut off points and why they vary model to model and which would best suit my radio / antennas

For ref -

Comet Antennas CF-530C Comet Duplexers | DX Engineering

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