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11/20/2019 5:07:11 PM
Posted: 11/3/2009 5:47:11 AM EST
First off, thanks for looking as always

I've been ogling the pics of various EMCOMM boxes here for a couple of years now. The concept of having a self-contained communications station is very appealing to me. No fuss, no mess-with everything you need and nothing you don't.

As I start to put together ideas for my own box I've got a couple of questions for those of you who run more than one radio in yours: First off, can I use something like a Comet duplexer to run two radios off of one antenna? If the answer is yes, can both radios transmit simultaneously-assuming that the combined output wattage doesn't exceed the rating of the antenna? Any intermod (or other) issues to worry about? Is it best practice to do it some other way?

Next, are there any issues running two radios off of a single power supply? My current power supply is an Alinco DM-330MV (switching, not linear) rated for 30A continuous and 32A surge. Assuming that I don't exceed the Alinco's rating, are there any issues doing this? Am I asking for trouble with things like interference, and if there are issues is there a straightforward solution-like running ferrite chokes on the wiring harnesses for example?

Thank you in advance for your expertise. My box will be built around an Icom IC-7000, and I would like to add an Icom IC-V8000 to the box as well-unless someone recommends a better alternative. The IC-V8000 seems like a bulletproof 2m mobile rig, and it looks like it would be a good compliment to the capability of my IC-7000.
Link Posted: 11/3/2009 5:56:49 AM EST
Depending on frequency coverage, yes a duplexer will work. Simultaneous TX would be rare, but as long as you have the power under the limit of the duplexer you'll be fine. You may still get birdies on one of the other rig even with a duplexer. The closeness of the rigs would be party the cause due to their mixers etc.

No problem running off the same power supply as long as it's rated for both. I really doubt you'd be in TX on both rigs at the same time.
Link Posted: 11/3/2009 6:21:48 AM EST
I've only got one radio in my box, so nothing to add there, but I did build my box around a V8000 and I can not recommend it enough. Great rig.
Link Posted: 11/3/2009 6:59:20 AM EST
Fantastic! Thanks for the expertise guys

ColourSgt, you are right-I really can't think of a (realistic) circumstance where I'd be TX'ing on both rigs at the same time either, unless two operators were using the station during an ARES call-out or something. The other circumstance I could think of would be using one rig for voice and the other for packet perhaps.

Beefington, I'm glad you like your V8000-I greatly appreciate your input Several of my new "HAM buddies" have them and rave about them as well. If I'm not mistaken, AR_Jedi runs one in his own box-right next to his 706. My 7000 is very similar to his 706, so the combination seems like a winner to me. I'm hoping that the 75w transmitter will allow me to run the rig at a lower output without worrying about heat. My 7000 runs fairly warm, particularly when I'm ragchewing simplex at full power.
Link Posted: 11/3/2009 7:18:37 AM EST
[Last Edit: 11/3/2009 7:27:50 AM EST by pcsutton]
I run 2 IC-7000's in my portable station. I use one primarily for HF voice and digital modes like MT63 and Olivia. The other I use for Pactor/Airmail on HF and to monitor 2 meter for local Ares/Races traffic interoperability.

For the one I use for Pactor AND 2 meter, I have a 2 meter vertical and a seperate HF feed coax which goes to an A/B antenna switch.

The other radio has only an HF coax going to the A/B antenna switch.

Now when I'm set up in my RV, the A/B antenna switch for HF goes to my Palstar balanced line antenna tuner. That is attached to an 80 meter dipole.

If I deploy where I cannot take my RV, the A/B switch goes to my LDG AT-200Pro auto-tuner. That feeds a portable AS-2259/GR NVIS antenna. I also have a mag-mount 2 meter antenna. This leaves me pretty portable as well as frequency agile.

As to power, I have a intelligent float charger in my case which runs off of 110v. It is connected to an absorbed glass mat battery. The battery is hooked into a DC power block which powers all the station gear. I also have a 12 volt power supply to run my laptop as it controls all my digital ops.

If I deploy, I just unplug the PS from the wall and when my battery needs charging, I plug into a portable generator.

In my humble opinion, you need a portable HF antenna for the IC-7000 (like the AS-2259/GR which you can homebrew), and a portable 2 meter antenna you can stick up anywhere you find yourself for the 2 meter rig.

Here is a recipe for a homebrewed AS-2259/GR: http://home.centurytel.net/w9wis/NVIS.html

Here is a really great article on using NVIS HF antennas for Emcomms and pictures of some great antenna/tuner setups:

http://txarmymars.org/lews_corner/NVIS%20ANTENNA%20THEORY%20AND%20DESIGN.pdf


ETA: I leave the back of the box open and have never had any heat issues with 2 radios, a pactor modem, power supply, rigblaster pro, and the antenna tuner running at the same time.


Link Posted: 11/3/2009 7:20:43 AM EST
Regarding heat, I usually run 5 or 10 watts, rarely 25, and pretty much never the full 75, so I can't say too much about heat buildup, but the radio does have a fan that runs for two minutes following every transmission you make, and the solid aluminum body is basically one big heat sink.
Link Posted: 11/3/2009 10:11:12 AM EST
Originally Posted By CJan_NH:
If I'm not mistaken, AR_Jedi runs one in his own box-right next to his 706. My 7000 is very similar to his 706, so the combination seems like a winner to me. I'm hoping that the 75w transmitter will allow me to run the rig at a lower output without worrying about heat.


I think ar-jedi runs a QRP 703+ next to his V8000.
Link Posted: 11/3/2009 5:13:49 PM EST
[Last Edit: 11/3/2009 5:15:21 PM EST by ar-jedi]
Originally Posted By BigDaddy0004:
Originally Posted By CJan_NH:
If I'm not mistaken, AR_Jedi runs one in his own box-right next to his 706. My 7000 is very similar to his 706, so the combination seems like a winner to me. I'm hoping that the 75w transmitter will allow me to run the rig at a lower output without worrying about heat.


I think ar-jedi runs a QRP 703+ next to his V8000.


like every ARFCOM'er, i "got both". i have a 706MkIIg and a 703+.

the 706MkIIg slices, dices, and makes coffee –– high power HF/VHF/UHF. it is a receive current hog.
the 703+ is HF-only (w/6m), has only 10W out, and has an integral autotuner. it sips current on receive.

(the 7000, which i don't own, has far greater receive DSP capabilities [IF versus AF] than either of the above).

pick your poison.

ar-jedi








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