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Author Topic: Complete system advice needed  (Read 8347 times)
KG7CZV
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Posts: 10




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« on: November 29, 2013, 11:57:28 PM »

Need mobile system advice.

Target vehicle: Hummer H1.
Primary Use: Fire/Rescue, emergency services

Would like to have: 80m/40m/20m, 2m/1.25m/70cm. Need ability to use legitimately on commercial/fire (VHF)/police(UHF) frequencies to communicate with local dispatch.  On the HF front, I'm happy with NVIS-only solutions if need be.

Want: fewest number of radios/antennas needed, within reason.

Bonus: If I could plug in a laptop for digital modes.

 All help appreciated.

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AF6WL
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Posts: 147




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« Reply #1 on: November 30, 2013, 12:09:38 AM »

If I had the vehicle, rather than a screwdriver whip, a HF NVIS roof half loop antenna would be my choice

http://www.stealth.ae/plugins/custompages/detinf.php?id=372&id_categories=136

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AC4RD
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Posts: 1235




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« Reply #2 on: November 30, 2013, 05:29:49 AM »


www.k0bg.com
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G8YMW
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Posts: 268




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« Reply #3 on: November 30, 2013, 06:37:19 AM »

One advantage with the Stealth NVIS is when its not in use, it looks like a Land Rover roof rack.
Very pricey though
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73 de Tony
Sent by WW2 Royal Navy signal lamp
KB4QAA
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Posts: 2488




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« Reply #4 on: November 30, 2013, 10:17:26 AM »

-Of course you need Part 90 commercially certificated radio for fire/ems operations.  I would use a dedicated radio and antenna for that and have a second radio and antenna for hams ops.

-I'm not aware of any NVIS antennas for mobile mounting.  I suppose some sort of horizontal loop around the perimeter of the vehicle might give some vertical directionality.  NVIS is effective only on 80m and sometimes 40m anyhow. 

-Another promo for Alan's website www.k0bg.com    Alan thinks very highly of Scorpion screwdriver type antennas.
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K0BG
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Posts: 9899


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« Reply #5 on: November 30, 2013, 02:29:51 PM »

The loop antenna made by Stealth Telecom in the United Arab Emirates, costs over $6,000 US dollars! It is advertised to provide NVIS from 2 to 30 MHz. That is a real stretch! NVIS over 5 MHz is nearly impossible, and difficult over about 3.5 MHz.

All you need is a decent screwdriver antenna, and a decent dual band VHF/UHF antenna. My vote goes to Scorpion for the HF, and a Larsen NMO2/70BK for the dual band. Total cost? Less than $1,000 delivered!

If you need digital, then buy an Icom IC-7100. Just don't use the suction cup mount!
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N6AJR
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Posts: 9927




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« Reply #6 on: January 03, 2014, 10:26:41 AM »

yup, a decent screwdriver antenna ( the scorpion is one tough customer) for HF and a larson 2m/440 for uhf/vhf would fix you right up.  make the screwdriver antenna a fold over mount so you can get into the boonies with a lower height clearence. a dedicated 2m/440 radio and a multiband rig like a ft 857 , a 706 M II G or such will give you lots of bands on a single radio.  Alan has lots of good stuff on his site.
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K0RGR
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Posts: 106




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« Reply #7 on: January 03, 2014, 05:45:11 PM »

You have some conflicting requirements, but we can try to sort it out.

Part 90 EMS frequencies need Part 90 certificated radios. Period, end of discussion. Modified ham gear need not apply.
The good news is that there may be a solution for VHF and UHF that won't cost a fortune.

The Wouxun KG-UV920P has an FCC Part 90 certification sticker on it. I would contact a dealer that caries them, like Radio City (radioinc.com) and ask them about the Part 90 compliance, as I suspect they will be aware of it along with any conditions. You can also go to the FCC web site armed with the certification number and look it (or you can search in other ways, too).  The UV-920P does not have a stellar reputation as a great VHF/UHF radio - the Chinese aren't quite there yet, but if you need the Part 90 aspect, this might be your best bet. You could also buy commercial radios and have some hame frequencies programmed into them.

1.25 meters - not in the same radio. ALinco and Jetstream make inexpensive 222 MHz. mobiles.

For HF mobile, I am partial to ICOM. The IC-7000 or 7100 both have many features that you will never use mobile, but they also have a good noise blanker and a much better DSP noise reduction system that will help with mobile operation.
My only knock on the 7000 is low audio output, and very hot operation. Initial reports on the new 7100 indicate that those problems aren't in the new model, but I have to wonder how well the touch screen will hold up in a mobile radio.
The TS-480 is a fine radio, too, and the FT857 is probably the most popular one out there right now.

Get a scewdriver - HiQ or Tarheel are good. Visit K0BG's site for info on mounting them.

I did look at that NVIS antenna - it comes in different models, one of which covers 1.9-10 MHz.. That might be a real winner for NVIS work, but lots of dollars, apparently (I couldn't find a price list - I guess if you have to ask, you can't afford it).  For 1/10th of the price as reported by K0BG, you can make a drive-on support to hold a 16 foot fiberglass pole that can support a horizontal wire attached to the top of a Tarheel. I do this trick with my pickup, and it works pretty well, but get an SWR analyzer so you can figure out where it's resonant.
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M6GOM
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Posts: 1012




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« Reply #8 on: January 04, 2014, 08:35:20 AM »

For a NVIS HF solution look at doing a horizontal loop tuned by a SGC230 antenna coupler. Look in the SGC 230 manual at the antenna suggestions pages to see what I mean.

For absolute reliability and ease of use for HF you need to be looking at the Kenwood TS480. The rest have smaller displays or displays you can't see in direct sunlight and have functions you want to be using buried in menus.
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KA2ODP
Member

Posts: 35




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« Reply #9 on: January 04, 2014, 09:41:22 AM »

As mentioned previously by KB4QAA, you will need a separate Part 90 certified radio for use on the fire & police frequencies to talk to dispatch.

One of reasons the model numbers of the various chinese radios seem to change monthly is because the FCC keeps cancelling their Part 90 certification due to the radio operator being able to program in the frequencies directly, like a Part 97 Amateur Radio.

The problem is the requirement of Part 90.203, which states:  transmitters designed to operate above 25 MHz shall not be certificated for use under this part if the operator can program and transmit on frequencies, other than those programmed by the manufacturer, service or maintenance personnel, using the equipment's external operation controls.

As soon as you modify the chinese radio for ham radio operation with a VFO mode, the Part 90 certification is voided.  You would have to use only the software to program the radio, as would be done by the manufacturer, service, or maintenance personnel.

The additional problem is that the chinese radios can only do analog 12.5 kHz narrowband operation for Part 90 operations.  If the fire and police departments switched to digital narrowband radio equipment, the analog radios will not work.  The FCC mandate for 12.5 kHz narrowband operation went into effect 1 January 2013 for all Part 90 operators.  Most Federal agencies went to P25 digital narrowband equipment.  Many county agencies went to 12.5 kHz analog narrowband equipment due to it's lower cost.  Either way, the days of 25 kHz bandwidth analog tranmissions for Part 90 operators is long past.

So, the best approach is a quality Part 90 radio, such as a Motorola, that can be programmed with both the Part 90 frequencies and the Part 97 ham frequencies.  Some of the analog models built within the last 10-years could be programmed for both 25 kHz and 12.5 kHz operation.  This would work for the ham frequencies (25 kHz) and the Part 90 analog frequencies (12.5 kHz).  The trick is finding a model that can do both at the same time.

Some of the cheaper, basic radio models could do either 25 kHz OR 12.5 kHz bandwidth, but not both at the same time.  This worked fine for fire and police departments who simply made the switch from analog wideband operation to analog narrowband operation by the 1 January 2013 deadline.  They simply changed ALL their frequencies to the new narrowband assignments.  The more expensive radio models could be programmed for 25 kHz or 12.5 kHz operation on a channel by channel basis.  This is the model that would work best for you.

By the way, I am a radio technician assigned to a 2-way radio shop on a military installation.  The narrowband deadline for Department of Defense functions was around 2007, so we already had to jump through the hoops to replace all of our 25 kHz wideband analog radio equipment.  Like many military functions, we switched to a digital narrowband trunked radio system to replace our old analog radios and repeater systems.

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