Icom IC-400Pro 25w mods

Submitted: Friday, May 15, 2009 at 07:10
ThreadID: 68842 Views:15483 Replies:5 FollowUps:9
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I and a few mates are conidering Icoms to get better range in the high country and have a few questions for those familiar with this process.

Can the high power channels be set to run with repeaters?
Can I use a standard antenna or do I have to use a high power one?
If I use version 1.2 software, can I modify the 40 UHF CB channels in the first bank?

Pleeeeeeease no "don't you know 5W is the max" posts, Yes I do, but I am not asking that question.
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Reply By: Member No 1- Friday, May 15, 2009 at 07:33

Friday, May 15, 2009 at 07:33
my old motorola accessed the repeaters in 25w mode

AnswerID: 364976

Reply By: Robin Miller - Friday, May 15, 2009 at 08:01

Friday, May 15, 2009 at 08:01
I haven't specifically looked at the ICOM for that purpose BooBook .
The Vertex was being advertized as coming with 25w from one supplier so I was going to get that but ran out of time.

I can also run 100w VHF if required and amateur VHF is fundamentally better anyway - but needs a license.

You don't need high powered antenna.

I understood that it was a frequency band selection - so once set it would make no difference if repeater or not.



Robin Miller

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AnswerID: 364980

Reply By: Member - Mottleman (NSW) - Friday, May 15, 2009 at 08:34

Friday, May 15, 2009 at 08:34
With the software and the cable you can do all you have asked about.
Regular UHF aerials taking into account terrain db gain considerations as per normal.
I would recommend duplicating chans 1-40 and then changing power etc on this menu selectable "2nd 40". So on your menu you have 5w 1-40 and 25w 1-40 which is selectable with 3 key presses. There have been numerous occasions where it was necessary to put out only 5w....
Please dont think you'll get 5 times distance though ... you dont ... it doesnt work that way.
cheers
John
AnswerID: 364986

Follow Up By: Boobook2 - Friday, May 15, 2009 at 08:51

Friday, May 15, 2009 at 08:51
John

Just the info I am after.

With the "2nd 40" channels, once you are using this set, does it look and feel much like the bottom 40 channels to use? This sounds good as my thinking is just to use the extra power in very hilly, bushy terrain to extend the range from a km or two at best currently.

I guess it is still pretty much line of site but do you think I could expect up to 5 or so kms? Ie how long is the piece of string?
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FollowupID: 632617

Follow Up By: MEMBER - Darian (SA) - Friday, May 15, 2009 at 09:10

Friday, May 15, 2009 at 09:10
Re using repeaters after your 'adjustment' to the 400 - would not the repeater's continued normal operating power and your normal reception performance for incomings be the snag ? Seems 25W is designed for grouped UHF's of that same spec, or maybe with a commecial spec repeater in the loop ?
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FollowupID: 632623

Follow Up By: Boobook2 - Friday, May 15, 2009 at 09:30

Friday, May 15, 2009 at 09:30
Not sure.

I guessed that repeaters would normally be up high and with a dammed good antenna. I even assumed they were more than 5W.

I would have thought that 25W to the repeater would help unless you were too close, then go to 5W. After all if the repeater recieves low quality signal, that is as good as it can retransmit. Dunno, Good question for those who have tried it.
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FollowupID: 632627

Follow Up By: Member - Mottleman (NSW) - Friday, May 15, 2009 at 11:34

Friday, May 15, 2009 at 11:34
2nd 40 looks and works exactly same ... just more power and more heat if you do a lot of trans.

Given same terrain and aerial I have observed usually between 1.5 to 2x range from 5x more power.

If you really want range, I'm sure you realise HF is the go! (which I have also)

cheers
John
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FollowupID: 632654

Follow Up By: Boobook2 - Friday, May 15, 2009 at 11:40

Friday, May 15, 2009 at 11:40
Thanks, sounds good.
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FollowupID: 632656

Follow Up By: Boobook2 - Friday, May 15, 2009 at 12:02

Friday, May 15, 2009 at 12:02
Forgot to mention John, yeah totally agree re HF, I also have one but can't twist others arms into $1500 plus. but a few are looking to get new UHF's so that will probably fly.
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FollowupID: 632662

Reply By: Shaker - Friday, May 15, 2009 at 09:55

Friday, May 15, 2009 at 09:55
The aerial is more important in the High Country than high wattage, as you are not looking for direct range as such, but the ability to transmit & receive over the hills etc. You will need to use an aerial with a relatively low db rating, we find that 4.5db is a good compromise, in some areas 3db would be even better, whereas on flat plains a rating of 9db would achieve maximum distance.
The aerial is the most important part of the set up as far as efficiency goes.
AnswerID: 365000

Follow Up By: Boobook2 - Friday, May 15, 2009 at 11:15

Friday, May 15, 2009 at 11:15
Shaker, it is sometimes true that for a given power depending on the conditions. What actually matters is the effective radiated power ERP and a low gain antenna is good for hills but a low gain antenna and more power will be even better :-)
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FollowupID: 632646

Follow Up By: Shaker - Friday, May 15, 2009 at 11:20

Friday, May 15, 2009 at 11:20
Correct, but a lot of people forget the aerial rating, so it was meant to be just a friendly reminder.
As they say in the classics ... aerials aint aerials!
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FollowupID: 632649

Follow Up By: Boobook2 - Friday, May 15, 2009 at 11:39

Friday, May 15, 2009 at 11:39
Antennas are a PITA to think about you, can easily get a headache. Maybe that's why people forget them. :-)

Actually, re the whole 3db - 9db hill verses flat thing, I do think this is overplayed too. I agree that 4.5db is generally a good compromise in hilly country on the basis that if you are in a group traveling along a dirt road then you are probably up to 1 - 3 km or so apart to reduce dust and on flattish roads with minimal vertical plain difference so a bit of distance to cover but, near horozontal.

How many times can you hear the guy behind you, but not the tail end charlie etc. When you are on the really hilly track stuff you are so close that a 20db antenna would probably work.

As they say, "Actual experiences may differ, we can not guarantee that any gain antenna will work wherever the hell you are."
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FollowupID: 632655

Reply By: muzzgit - Sunday, May 17, 2009 at 23:27

Sunday, May 17, 2009 at 23:27
Up until recently me and my travelling buddy used old Philips commercial UHF tuned to CB frequencies and running at about 18 watts. We both used the same elevated feed 4.5db aerial and we found on the highway, in the bush, up sh*t creek, wherever we were, we could get further than anyone using standard 5W.

I personally think we could have done even better had we put the aerial on the roof instead of the roo bar.

We constantly bumped into people who said they could hear us talking to each other but when they called we didn't respond. Some assumed we had CB's that blocked others out but we don't, we just couldn't hear them, but they heard us no worries.
AnswerID: 365447

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