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Author Topic: Starting out.  (Read 5534 times)
KF5IZN
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« on: May 05, 2012, 08:52:07 AM »

I got my Technicians ticket about a year ago, but haven't done much with it.  I will be buying an FT-7900R within a couple of weeks.

I have 5 pieces of of 4' Fiberglass mast and plan on building a Copper tubing J-pole antennae this week.  Hopefully I will be able to use it on UHF as well. I intend to use it to monitor GMRS also.   My setup  initially will be a couple of milk cartons set up on my patio.    I have an antique Hewlett Packard Variable voltage Power Supply wit Adjustable current limiting
Its pretty flat around here without a lot of trees.  Much of my transmissions will be over open water.   
There are some things I'm not real clear on .

1: Before I bring COAX into the house I need to figure out how to ground the Antennae. Do I just solder on a ground strap at the horizontal member?
2: I understand that there is a lot of factors about distance.  Assuming that I get a decent  SWR match on UHF what can I expect for UHF performance. 
3: I only have Linux computers easily available.  Are there any programs that will let me set up my frequencies on the FT-7900? I would be willing to use WINE if that is what it takes.
4: Does my Setup sound reasonable any tips for a real newbie

TIA


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N5VTU
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« Reply #1 on: May 05, 2012, 07:49:43 PM »

One of the things of concern is the "antique Hewlett Packard Variable voltage Power Supply".  If this is a lab supply, it likely doesn't have near enough current output to power your radio on xmit, and maybe not even on receive.  The specs on the FT-7900 call for 9amps on transmit.  Also, many lab supplies are variable voltage over a wide range, such as 5-30vdc.  The voltage spec for your rig is 13.8 vdc +/- 15%.  Hit the rig with 16v or more and its days will be numbered.  To be safe, you should consider a 12v nominal switching or linear supply with at least a 15A continuous rating or use a 12v battery.

As far as the antenna, do a Google search for J-pole antennas.  There are lots of plans available and they are relatively simple to make, but they are not exceptional performers.  UHF is mostly line of sight, so height above obstructions is important, tempered with reasonable coax lengths, since losses add up quickly at UHF frequencies.  Do a search for coax loss calculators online and you'll see what I mean.

I can't offer any advice on the programming software with Linux.  I use the ADMS software on Windows.

Good Luck,

Stephen
N5VTU
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K9KJM
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« Reply #2 on: May 05, 2012, 09:11:55 PM »

Also be aware of coax loss.   For a short coax run, Say you only need 25 or so feet from the radio to the antenna, It is not very critical at all, And even some decent RG8X, Or "Mini 8" would work out just fine.
IF you need a longer run of 75 or so feet, Get some Times LMR 400 coax.

Also do some research into getting a Yaesu FT 8800 instead of the 7900.   The 7900 is a fine dual band radio, But the 8800 is actually TWO radios in one box, That can also cross band repeat, And gives you the ability to monitor two frequencies at the same time.   With the simple snip of a diode, The 8800 can be made to transmit on GMRS, Business band, Marine, etc  in the event of a true life threatning emergency.
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K8GU
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« Reply #3 on: May 06, 2012, 05:09:18 AM »

Welcome to the hobby! 

Let me address some other things you've been told first.  HP made a lot of different power supplies, some of which are great for powering ham gear, some of which are not.  Like the other poster said, be sure that it is capable of supplying enough current at 13.8 volts when you're transmitting.  My club has a big, heavy HP rack-mounted supply that powers an entire rack of beacons for 10m/6m/2m/70cm/33cm/23cm that draw about 20 amps on transmit. 

Any kind of omni-directional antenna is going to leave a lot to be desired as far as range on VHF/UHF.  But, if you want that kind of coverage, you trade off.  Use good quality coax.  LMR-400 is good, but there are many variants and knock-offs on eBay and elsewhere.  Be careful!

Now your questions:

1.  The first thing you must ask yourself is:  why are you grounding?  If it's for lightning protection, there's a whole litany of things you'll want to do.  Have a look at some of the lightning protection system companies' web sites (e.g., PolyPhaser).  If it's for any other reason, it's probably a waste of time, and depending on your present location and planned installation, lightning protection may also be a waste of time.

2.  SWR tells you almost nothing about the range performance of your system.  If you really want to know, you'll want to try using software like Radio Mobile.  It has a learning curve but can tell you a lot.  I think there's something similar for Linux, but I can't for the life of me remember the name so it may not exist!

3.  Google would be as much help as I would on this one.  Most good ham software is Windows-based.  There is some good stuff for Linux, and very limited offerings for the Mac.  I own all three kinds of systems and my two shack computers are Windows/Linux machines that are mostly booted to Windows when hamming.

4.  It all depends on what you want to do.  If you're just exploring ham radio, I'm not sure I would recommend that anyone start on VHF/UHF FM.  It's not nearly as popular as it was 20 years ago, so you will have a limited group of people to work with.  However, if you know that you want to communicate locally and play with APRS, etc, it's a good choice.
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KF5IZN
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« Reply #4 on: May 06, 2012, 07:17:11 AM »

Thanks for the replies .
The power supply will do 25 amps. it is also has course and fine settings for the current as well as the voltage. I also have a good Fluke meter to help me set it up.  The supplies also have current and voltage meters on the front of it.   I understand that it will be easier and better to eventually get a fixed supply. But free is free and If I'm careful this should get me started.

I haven't bought the coax yet. To tell the truth I hadn't looked at the LMR-400 but it is reasonably priced  with decent specs thanks for the recommendation.  All I need to do now is figure out how much I really need.  I have the 20 Ft of fiberglass masting and most of the parts to build my antennae.  I live on Galveston Island there aren't any hills trees nor many tall buildings within a 100 miles. There are supposed to be a couple of Repeaters here on the Island, but I haven't heard much activity on them from my little handheld.   I hope I will get to use the UHF bands, but I suspect I will transmit more on VHF.  and be listening and monitoring more on UHF.  

I have looked at the 8800 And might buy it if I have the extra $100  but right now my main goal is to get a nice little VHF rig now (UHF is just an extra). and  maybe next year get a fancier multiband radio like the Icom 7000. and get my General.   I've put off putting together a setup for to long.  



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N5VTU
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« Reply #5 on: May 06, 2012, 08:50:29 AM »

KF5IZN,

The Tidelands Amateur Radio Club is a very active club with some great Elmers who could get you headed in the right direction.  They are just north of you in Texas City.  Perhaps you could get involved with them.  I believe they maintain a 2m repeater on 147.140 and a UHF repeater on 442.025.  I used to work with their Director, Bill WA5WVP at Shell Refinery in Deer Park.


http://www.tidelands.org/

Good Luck
Stephen
N5VTU
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KF5IZN
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« Reply #6 on: May 06, 2012, 09:00:03 AM »

Welcome to the hobby!  
Thanks!!! I thinks this might turn out to be a lot of fun.

Let me address some other things you've been told first.  HP made a lot of different power supplies, some of which are great for powering ham gear, some of which are not.  Like the other poster said, be sure that it is capable of supplying enough current at 13.8 volts when you're transmitting.  My club has a big, heavy HP rack-mounted supply that powers an entire rack of beacons for 10m/6m/2m/70cm/33cm/23cm that draw about 20 amps on transmit.  
I think we might have the same or simular PS.  Mine is a Model 6434B. Its pretty hard to beat free.
Any kind of omni-directional antenna is going to leave a lot to be desired as far as range on VHF/UHF.  But, if you want that kind of coverage, you trade off.  Use good quality coax.  LMR-400 is good, but there are many variants and knock-offs on eBay and elsewhere.  Be careful!
We have to start somewhere. I have the Mil Surplus mast segments.  I can't imagine it supporting a big Yagi.  This set up should be pretty portable, and allow me to hit a few repeaters at lot better than my tiny handheld.  I was impreSsed at the price of the LMR-400 as it seems to be runining not much more than RG-58U.

Now your questions:

1.  The first thing you must ask yourself is:  why are you grounding?  If it's for lightning protection, there's a whole litany of things you'll want to do.  Have a look at some of the lightning protection system companies' web sites (e.g., PolyPhaser).  If it's for any other reason, it's probably a waste of time, and depending on your present location and planned installation, lightning protection may also be a waste of time.
i am concerned about lightning.  My wife wouldn't take kindly to burning the house down.  For the time being though I will plan on setting up the  antennae ungrounded and using the radio out on my patio. I will take down the antennae when not using it.  Setting it up or taking it down should be a ten minute job. eventually though I like to set up a permenent radio shack indoors.  Maybe even a tower.
 

2.  SWR tells you almost nothing about the range performance of your system.  If you really want to know, you'll want to try using software like Radio Mobile.  It has a learning curve but can tell you a lot.  I think there's something similar for Linux, but I can't for the life of me remember the name so it may not exist!  

SWR is probably a good place to start.  Mostly though I don't want to burn up the radio.  I have pretty goog confidence that I'll get enough range in VHF to keep me happy for a while. The Jpole is a $20.00 investment. and I should be able to easily set it up as a remote.  

3.  Google would be as much help as I would on this one.  Most good ham software is Windows-based.  There is some good stuff for Linux, and very limited offerings for the Mac.  I own all three kinds of systems and my two shack computers are Windows/Linux machines that are mostly booted to Windows when hamming.
My main interest in software is to program the memories and such in the 7900.  I have netbooks that could be booted into window, but I don't have a cdrom.  The easiest thing will be to borrow my wifes laptop to program it.  I am interested in digital packet communications, but I believe there is plenty of good software for that in Linux(ubuntu)

4.  It all depends on what you want to do.  If you're just exploring ham radio, I'm not sure I would recommend that anyone start on VHF/UHF FM.  It's not nearly as popular as it was 20 years ago, so you will have a limited group of people to work with.  However, if you know that you want to communicate locally and play with APRS, etc, it's a good choice.
As a beginner I only have a Technicians licence.  My interest in Ham is mostly about community. I have some friends about 50 miles away that are hams and I have an interest in Emergency response.  I am in a Hurricane sensitive area and I see ham radio as an important part of personal and community preparation.  Long distance communications sounds like a lot of fun and I look forward to doing this some day.  but for now VHF/UHF  seems like the quickest/cheapest way to get into this.   I am beginning to understand that any success with UHF might be spotty. but I was hopping to be able to make some use of half of my radio.
I have carried out a conversation on a handheld GMRS 15 miles away. I might be able to reach a repeater with up to 45 watts and some real height  available.  

Thanks muchly for the feedback  I will be checking out grounding solutions even though I won't be needing it for a while.  
« Last Edit: May 06, 2012, 11:34:49 AM by KF5IZN » Logged
KJ6OWH
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« Reply #7 on: June 08, 2012, 05:23:47 PM »

As a new Tech myself, I am in the same boat. If you are running a base station, it would be well worth the extra $100 for the 8800 over the 7900. Monitor the GMRS while hitting the repeater on the other channel. I loved the 8800 while playing at the HRO, but was not suited for my mobile application, so I opted for the 7900 as the buttons were friendlier.

Times LMR-400 is attractively priced for the performance, but hard to work with as it doesn't really flex and you can't bend it.

I did the mod for the 7900 and it was simple and quick. Imagine it's the same for the 8800.

And use the FTB7900 software by G4HFQ and will probably end up getting it for the 897D as well. Simple operation and works well.

 
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KC9AXZ
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« Reply #8 on: June 12, 2012, 05:02:46 PM »

LMR 400 comes in different flavors. You can get standard LMR 400 that would be full copper. There is the LMR 400LW that is copper clad aluminum, and lighter weight. There is also LMR 400UF which is "ultra flex" and has stranded conductor rather than a solid conductor.

Jon KC9AXZ
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