APX Dual Band Mobile Antenna ?

[Outerbanks4wd]

Can you use a Comet 4160 ( COMET CF-4160K ) duplexer, to combine antenna outputs from the radio so you can use one antenna to the vehicle roof, w out damaging the radio? I have one ea, APX7500 VUHFR1, one HP, one dash mount. The guy at HRO was saying something about needing an TX switch in the radio to protect the radio from RF coming back into the radio from the other band/side? He suggested an AB switch. Any suggestions?
Thank You,
Mark W4IAD

 

[MTS2000des]

Not true at all, you can indeed us a diplexer and a dual band antenna with a 7500. MSI even sold diplexer with mini-UHF connectors for such a radio. I have one somewhere in a box. You can use a standard "hammy" one but you'd need RF adapters to go from full size UHF to mini UHF.
The entire purpose of the diplexer is to prevent RF from going where it shouldn't. HRO guy is misinformed.

 

[prcguy]

I have a VHF/UHF R2 7500 and use a Comet CF4160J diplexer which has all female connectors allowing correct jumpers between the diplexer and radio. This diplexer is rated 1.3-170MHz on the VHF side and 350-540MHz on the UHF side. I packing this radio up today to send to the APX Unchained guys to get it modded down to about 430MHz for some hammy stuff.

 

[KevinC]

Not true at all, you can indeed us a diplexer and a dual band antenna with a 7500. MSI even sold diplexer with mini-UHF connectors for such a radio. I have one somewhere in a box. You can use a standard "hammy" one but you'd need RF adapters to go from full size UHF to mini UHF.
The entire purpose of the diplexer is to prevent RF from going where it shouldn't. HRO guy is misinformed.

I "think" he wants to combine the TX from the two different radios into one antenna. That would work as long as only one antenna port was used on each radio. And used each radio on different bands.

 

[prcguy]

I "think" he wants to combine the TX from the two different radios into one antenna. That would work as long as only one antenna port was used on each radio. And used each radio on different bands.

Leave it to a mod to wreak what we think is a perfectly good post. But yea, two antennas would be the best approach there with a diplexer on the 7500 and probably a tri-band on the HP. Get some reasonable separation between antennas to avoid damage to the HP.

 

[KevinC]

Leave it to a mod to wreak what we think is a perfectly good post. But yea, two antennas would be the best approach there with a diplexer on the 7500 and probably a tri-band on the HP. Get some reasonable separation between antennas to avoid damage to the HP.

That's how I interpreted his post, I could be completely wrong.

 

[N4DES]

That's how I interpreted his post, I could be completely wrong.

I read it the same way, two separate radios operating into one antenna and both of them are "APX7500 VUHFR1, one HP, one dash mount".

 

[chief21]

I have one ea, APX7500 VUHFR1, one HP, one dash mount.

Hi Mark - I'm not sure how to interpret your post. How many radios do you wish to hook to one antenna, and which bands will be used on each radio? Thanks.

 

[Outerbanks4wd]

Hi Mark - I'm not sure how to interpret your post. How many radios do you wish to hook to one antenna, and which bands will be used on each radio? Thanks.

Didn't mean to confuse anyone... Two different Dual Band APX's, each has a antenna port for VHf and UHf. One vehicle, 04 Tundra has limited roof area due to sunroof and wanted to use a dual band antenna for the 7500. Want to combine the antenna ports, from one radio to a Du/Diplxer to be able to use one antenna on the roof. My Suburban will get the HP, so yes want to run one antenna dual band for that vehicle as well. Thks, Mark

 

[prcguy]

Didn't mean to confuse anyone... Two different Dual Band APX's, each has a antenna port for VHf and UHf. One vehicle, 04 Tundra has limited roof area due to sunroof and wanted to use a dual band antenna for the 7500. Want to combine the antenna ports, from one radio to a Du/Diplxer to be able to use one antenna on the roof. My Suburban will get the HP, so yes want to run one antenna dual band for that vehicle as well. Thks, Mark

Why two APX7500s with the same bands?

 

[KevinC]

Why two APX7500s with the same bands?

Two different vehicles.

 

[prcguy]

Two different vehicles.

Of course, I knew that. Or my dementia is finally kicking in.

 

[nokones]

I wouldn't use some POS Ham junk with a high quality perfectly good Motorola radio. I would do it right with the Motorola TriBand Multiplexer, you can run either one dual or Tri-Band radio with separate RF outputs on one All band Antenna or three separate (VHF, UHF, and 700/800) radios on one All Band Antenna.

The Motorola Multiplexer and the All Band Antenna would run about $225 for each the multiplexer and antenna.

 

[prcguy]

I wouldn't use some POS Ham junk with a high quality perfectly good Motorola radio. I would do it right with the Motorola TriBand Multiplexer, you can run either one dual or Tri-Band radio with separate RF outputs on one All band Antenna or three separate (VHF, UHF, and 700/800) radios on one All Band Antenna.

The Motorola Multiplexer and the All Band Antenna would run about $225 for each the multiplexer and antenna.

I have Motorola high power and medium power triplexers, Sti-Co triplexers, Panorama triplexers and other high end di and triplexers and the performance of the Comet CF4160J is on par with any of them at much less $$. Also, the Motorola triband antenna, actually made by PCTEL is at best a 1/4 wave equivalent on each band and a little worse on some bands. A dedicated dual band amateur antenna like the Larsen NMO2/70B will greatly outperform it as will the wider band amateur/commercial Comet CA-2X4SAR. I have several of each that I have tested for gain.

If you really must have a Motorola/PCTEL antenna there was a guy in Canada, eh, selling them new for about $18 and I stocked up on many. They show up for fair prices from other dealers on eBay.

 

[Outerbanks4wd]

Why two APX7500s with the same bands?

Two vehicles.