AR15.Com Archives
 2 Meter Amplifier
ThePrepared_com  [Team Member]
12/10/2007 10:53:35 AM EST
I've never really researched amplifiers but thought I would start my quest here. What does everyone recommend? I would like to spend less than $500.

--Scott
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frisco  [Member]
12/10/2007 11:02:41 AM EST
Probably should quantify what you're trying to do.

You can probably guess what I might suggest, but at VHF, you can get more dB for your buck in antenna and feedline vs an amplifier.


ThePrepared_com  [Team Member]
12/10/2007 11:11:02 AM EST

Originally Posted By frisco:
Probably should quantify what you're trying to do.

You can probably guess what I might suggest, but at VHF, you can get more dB for your buck in antenna and feedline vs an amplifier.




I'm actually planning to buy some better feed line. I am currently using an Arrow J-Pole for the Antenna but am looking at Ground Planes etc for a more efficiency.

Basically the group I am working with would like to use 2 meters for longer distance communications (150 Miles or so).
frisco  [Member]
12/10/2007 12:10:00 PM EST
For 2m FM, height and system losses are where's it's at....not necessarily power.

The term alligator comes to mind....(All mouth, no ears)

J-pole is fine, but for longer distance, more gain, a 2m yagi is a much better choice...M2 makes a 9el with elements tuned for the FM portion of the band. You can find similar products with other manufacturers.

Second on my list would be phased 5/8 wave verticals, but the yagi is my first choice.

With 9el, 12dbd yagi and 50watts, your ERP becomes 800watts. The M2 antenna runs $168 plus shipping. Not sure you can find an 800w amp for the same amount of cash.

Try to run the best coax you can...LMR 400 at least...600 or equivalent even better...if it's a longer run, hardline.

Loss for 400 is about 1.5db per 100ft
Loss for 600 is about 1.0db per 100ft

Lastly, you'll need height...as much as you can get...but most important will be HAAT between the two points you wish to communicate with.

2m SSB is a more power efficient choice for longer distance local contacts. But again, height and gain are important.
speedy9mm  [Member]
12/10/2007 2:40:33 PM EST
I agree with Frisco. You would be better off with a 2m yagi. I use a Cushcraft 13B2 up about 50 feet and really see no need for an amplifier at all and just use the power from my Icom706. Mine is run with LMR-400 coax and over the last 10 years of being up I have never had a problem. 2m yagis are not really that expensive compaired to spending money on a 2m amplifier and then also a power supply if ran indoors.
speedy9mm  [Member]
12/10/2007 2:41:05 PM EST
I agree with Frisco. You would be better off with a 2m yagi. I use a Cushcraft 13B2 up about 50 feet and really see no need for an amplifier at all and just use the power from my Icom706. Mine is run with LMR-400 coax and over the last 10 years of being up I have never had a problem. 2m yagis are not really that expensive compaired to spending money on a 2m amplifier and then also a power supply if ran indoors.
Gamma762  [Team Member]
12/10/2007 3:29:46 PM EST
Good gain antennas and reasonable towers, 150miles is no real stretch on 2m with 50w at each end.
ar-jedi  [Team Member]
12/10/2007 3:38:33 PM EST

Originally Posted By frisco:
2m SSB is a more power efficient choice for longer distance local contacts.
But again, [for long distance work at VHF] height and gain are important.


to the OP:

re-read the two sentences above.
they are the most important sentences this thread will ever have.

ar-jedi
EXPY37  [Member]
12/10/2007 6:53:57 PM EST
2 meter amplifiers are relatively easy to build and there should be kits available inexpensively. We were building them in the late 70's even.
radioshooter  [Member]
12/10/2007 8:20:30 PM EST
There are some guys local to upstate SC that use beams to make 40 to 60 mile contacts using 2 meter FM radios on a regular basis. I had no trouble making the contact with them using 50 watts on a 3db vertical antenna at about a 25 mile distance. The problem with a 150 watt "brick" is that it uses a lot of 12 volt current (30 anps or more). That means a big power supply ($200.00). A 2 meter beam can get you 10 db of gain on receive and transmit for less than that. That make a 50 watt rig look like a 500 watt rig on the othe end. Even with a good beam, 150 miles could be too far for regular contacts without repeaters unless you are working over some real flat terrain.

2 cents worth
RS
aaron_fsp  [Member]
12/10/2007 8:58:00 PM EST
I did some experimentation with an aluminum extension ladder and
c clamped a 2M antenna with ground plane to see how a rise in elevation
of the antenna might help my signal. By the end of the week, I had
two 21' waterwell pipes joined vertically as a mast mounted to the gable
of the house.

Best investment I ever made, even with the new run of coax.
I never needed the higest power setting again after that.
Grog  [Team Member]
12/11/2007 12:08:57 AM EST
I remember in the late 90s when I was a new ham in Myrtle Beach, there was a pair of OFs who would have a morning QSO on the Dillon SC 145.745 repeater (I-95 near the NC/SC stateline). One OF was near Dillon and the other was in Hickory NC. I tried to call them after their QSO (I mean within 5 seconds of them sighing off) but they were a couple of old fart extras who could not be bothered to talk to a lowly no code ham. Needless to say I never found out what the Hickory station was using to talk to a repeater 150 miles away


I should add that the Dillion repeater was on a 2000 foot tower, so that helped quite a bit in that flat area but he still had to have a good setup to make it that well on a daily basis.
444  [Team Member]
12/11/2007 12:46:11 AM EST
Ok, let's start off with some facts:
Can you hear the stations you want to work with the antenna you are running now ? If you can hear them and you can't work them an amp might very well be a big help to you. Secondly, if you can hear them (all the time) then you can work them just like they are working you. 150 miles is a long way on 2m Simplex. If I remember correctly, without some form of propagation or a repeater, you can only work 10 degrees beyond the visible horizon when you are operating beyond the maximum usable frequency. That being said, it might be possible in Wyoming and again, if you can hear them it is absolutely possible to work them.
Yes, a better antenna is always the first thing to improve and it is always the best place to put your money. But, you asked about 2m amplifiers. The only two meter amplifiers I have any experience with are the common "brick" amps made by RF Concepts or Mirage with Mirage being the most common by far. They run on 12 volts and if you get one that puts out decent power they draw a lot of current, so you are going to need a power supply capable of providing that current. I used to run a 160 watt Mirage amp to work Simplex over 50 miles. There isn't really much to say about it. The hook up and controls are self explanitory and it worked great.
In true ARFCOM style I say, get both. Just because you buy an amp doesn't mean you can't be constantly trying to improve your antenna. And, just because you improve your antenna doesn't mean an amp wouldn't be a good investment. Again, I would (and have) get both. If you want/need to communicate 150 miles on 2m Simplex on a consistent basis, you are going to need to be running some significant (for 2m) power as well as having a better than average antenna (unless you live on a mountain top and you have a line of sight to the intented target).
Grog  [Team Member]
12/11/2007 3:05:52 AM EST
Plus if you ever need to use this with emergency power (IE;;batteries) then you will quickly use a ton of juice, where the antenna is "free power".....
ThePrepared_com  [Team Member]
12/11/2007 4:46:57 AM EST
Here is a bit more info. I am at 6178 ft. The intended target is at 5200-5300 ft. My mast is currently sitting at 25-30 and will be at 50 ft eventually. There is a hill between the me and the intended target that sits at 6300 ft. The intended target is between 100-115 miles away to my South.

On Sunday I did some testing with them. I was using the following setup.
-Yaesu FT-8900R
-Arrow J-Pole
-50 watts
-100ft of RG58 coupled together with a barrel (I know that this is currently my week link)

They were able to hear me at about a S1 with background noise. I was able to hear them at about a s3 with a bit of static.

One week earlier I did a test with another group that is 45 miles to my South. They sit at about 5100 ft in elevation. The only difference was that I was using an Arrow 4 Solid Element Yagi. They were barely able to make out my signal at all. I put that antenna together and instructed but don't have equipment for measuring SWR at the moment. I'm wondering if there is an issue there. I'm also wondering about the direction I had the antenna pointed.

I'm going to hunt someone down who has an antenna analyzer and see what I can figure out on that end.
frisco  [Member]
12/11/2007 5:15:52 AM EST


Here is a bit more info. I am at 6178 ft. The intended target is at 5200-5300 ft. My mast is currently sitting at 25-30 and will be at 50 ft eventually. There is a hill between the me and the intended target that sits at 6300 ft. The intended target is between 100-115 miles away to my South.


If you want reliable in that scenario, you'll need a 200ft tower....

Short of a 200ft tower, here are some options.

Keep in mind, even if you buy a big brick, you're only going to gain about 1s unit.

RG-58 has about 6.8db loss per 100ft at 150Mhz. First thing I would do is change to LMR-400...that will buy you about 5db or almost 2s units. You can get this done for less than $100 bucks....(last I checked 400 was going for about .65/ft)

In this case, height above any tress or obstructions will help, but beyond the trees, the only other thing that can help is getting above the hill.

Couple things about the yagi:

If you're using FM, make sure the elements are vertically polarized (pointing up and down.
Double check bearing of yagi in relation to your target.
Don't worry about SWR....commercial 2m yagis' will be close enough. Besides, you can see when somethings wrong when the rig starts rolling back the power.


ThePrepared_com  [Team Member]
12/11/2007 6:29:08 AM EST
Is anyone here using the LMR cable? Did you buy it with connections attached? I've ready that you may need to buy special tools to assemble the connectors.

I'd hate to buy it with connectors on because I need to run the cable through a whole drilled in the mortar between bricks.
frisco  [Member]
12/11/2007 8:16:56 AM EST
I have several runs of LMR...some 600, most 400.

LMR 400 uses the standard size PL-259 or N connectors that can easily be soldered. (.405 outside diameter)

You're probably thinking of the crimp style connectors that work equally as well, but require special dies and crimping tools.

I'm a big supporter of the amphenol connectors for good reason.

It's a good idea to have several on hand anyway...but if you only need a couple for your run, shoot me an IM with your call and I'll mail you a couple.

AES carries the amphenol line of connectors.

A good link on how to solder connectors:

www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/SolderCoax.htm

Ready made cable can be bought, but you would have to open up your hole a bit. I believe you need a 3/4" hole to pass a pl-259.
speedy9mm  [Member]
12/11/2007 10:41:44 AM EST
I used LMR400 for just about everything here and never had a problem with it. I bought it in a bulk roll and then put on my own connectors with the same common tools I have always used.
DW_Drang  [Team Member]
12/11/2007 12:00:35 PM EST
There was that home-brewed yagi antenna made from sections of tape measure, that got written up in QST... It probably works as well as--and probably packs better than, if you care--the yagi we "kimchi rigged" from otherwise unserviceable dipole sections of RC-292 antenna, one winter in Korea. Came in handy during Team Stupid.
EXPY37  [Member]
12/11/2007 3:25:41 PM EST

Originally Posted By ThePrepared_com:
Here is a bit more info. I am at 6178 ft. The intended target is at 5200-5300 ft. My mast is currently sitting at 25-30 and will be at 50 ft eventually. There is a hill between the me and the intended target that sits at 6300 ft. The intended target is between 100-115 miles away to my South.

On Sunday I did some testing with them. I was using the following setup.
-Yaesu FT-8900R
-Arrow J-Pole
-50 watts
-100ft of RG58 coupled together with a barrel (I know that this is currently my week link)

They were able to hear me at about a S1 with background noise. I was able to hear them at about a s3 with a bit of static.

One week earlier I did a test with another group that is 45 miles to my South. They sit at about 5100 ft in elevation. The only difference was that I was using an Arrow 4 Solid Element Yagi. They were barely able to make out my signal at all. I put that antenna together and instructed but don't have equipment for measuring SWR at the moment. I'm wondering if there is an issue there. I'm also wondering about the direction I had the antenna pointed.

I'm going to hunt someone down who has an antenna analyzer and see what I can figure out on that end.


I'm sure you did but have to make sure -was your Arrow beam polarized correctly? It should easily outperform your vertical. Something's wrong if both antenna elevations were the same. Did you try both antennas at the same time?

If your 150 mile contact and you can hear each other there is hope, plenty of it.

1] There will be some atmospheric component [almost certainly] to your 150 mile propagation link and you can expect a lot of signal variation.

2] I'm guessing you are running at least 50 feet of coax. The feedline attenuation is critical and if you are running, say, RG58 at 145 mc then the line attenuation will be about 3+ db incl connectors and real world effects. This means if you have 40 watts going into the line you have less than 20 coming out into the antenna, if everythings matched OK.

3] The best bang for your $$$ will be a high gain yagi [try the one you already have] on a rotor and a remote mounted transmit amplifier with a Gasfet receive preamp.


Here's just one of several ads for one used:
[08-Dec-2007] Mirage B1016 2M Amplifier with receive preamp. 10W in, 160W out, FM or SSB. Measured output with 11W drive in FM mode, 144 MHz 140W, 145 MHz 155W, 146 MHz 160W, 147 MHz 150W, 148 MHz 140W. $135 plus shipping. kn3c@arrl.net

In the early seventies, I could work the 2M Mt Mitchel [IIRC] repeater from just outside Concord NC, using an HT220 W/T [2 watts out], a beam at about 30 feet and an RG8 coax run of about 50 feet. Including the lossy antenna adapter that 'plugged' into the top of the radio. LOL.

The 'tower' was two about 2 1/2" vertical pipes set in concrete and about 6 feet tall. The mast fit between them and pivioted at the top of the 2 verticals. I used a com-a-long to pull the mast between the 2 vertical pipes and pushed it the rest of the way after the stroke ran out.

The mast was a length of 2 1/2 pipe with a shorter length of 1 1/2 inch pipe attached to it.

It stayed up in some storms the 2 years I was there with an 11 element yagi [IIRC] and I think a 1/4 wave vertical.

4] If you go with the remote mtd amp, you won't need new coax and a trickle charged 12 V battery at or on the mast will power it fine.

5] A rule of thumb I use is that every additional dB you can save at the antenna, feed, and radio side improves your audible signal to noise ratio 1 dB. This might not be correct [I'm not a math genius like some here] but it's what I use for microwave sat link work.

Sounds like you have an interesting project and please keep posting about it! You are going to learn a hellava lot if you keep at it!

ETA So if you get 150 watts into the antenna, vs 20 watts now, that's about an 8dB improvement and a good GasFet preamp on the your receive end, figure that if the received signal was not full quieting before, it will be now.

The xmit 8 dB improvement translates to being not full quieting but readable to your buddies to being full quieting to them.

The downside is and there's not anything you can do about it, is atmospheric propagation can make a 20 dB difference easily.

Have you considered NVIS with cheap equpment as a backup?
444  [Team Member]
12/12/2007 3:05:28 AM EST
As you can see, this is a process. Your station is a system: radio, amplifier, feedline, antenna.
To repeat what I (and others) have said, if you can currently work each other, things can only get better. This isn't magic. It is certainly doable. In your last post you are talking about distances of just over 100 miles. That shouldn't be a problem at all. I used to work a guy every night close to that far away. I was using a Ringo Ranger, so it isn't a big deal at all.
You have identified several weak links in the system. Each one will make the whole system work better. You asked about an amp and this question has been largely ignored. It WILL make a significant improvement in signal when working long distance FM simplex and if you want to work these guys with the best possible signal you are going to eventually get an amp. I would look at this (this is what I had and am going to get another one): Mirage B1018G

http://www.rlham.com/cgi-bin/shop/modellookup.dbw?MODEL=B1018G Mirage B1018G

What are THEY using for antennas ?
444  [Team Member]
12/13/2007 6:32:23 AM EST
Back on the subject of amplifiers: Many hams consider the word amplifier to be a dirty word. Their inital knee jerk reaction is to always advise against an amplifier and even if they arn't completely opposed to using one, they consider it only as a last resort.

I am not one of them.

There are many times when an amplifier is a nice asset. There are times when there is absolutely nothing negative about running as much power as you possibly can.
Yours is one of those cases.
First of all, you live in Wyoming. If you were running 2kw (just as an extreme example) on two meters simplex it wouldn't hurt anything at all and certainly will help your signal immesely no matter what antenna you are using.

There are also situations where an improvement in your antenna is not possible or practical. The car is a good example. I have a nice duel band antenna mounted in the center of my vehicle. There are times and places where I am noisely or can't communicate with the person I want to communicate with. The answer ? Run more power. And, there is nothing negative about it. It won't hurt a damn thing. My home is another example. I live in a community where outside antennas of any kind are strictly forbidden. So, I am running one of those Ventennas. It is an outside antenna about 20 feet in the air and is actually a hell of an antenna for the conditions I am living in. There is absolutely no possibility of putting up any better antenna. So, if the performance isn't what I need, the only option I have is to run more power.
The classic argument heard is that there is no point in being able to talk further than you can hear. Obviously that's true, however, who said that other people don't have up better antennas than I do and are running more power than I am, and I can hear them fine: they just can't hear me ?
frisco  [Member]
12/13/2007 9:19:40 AM EST

Originally Posted By 444:
...


I think you totally missed the boat on this one. I own several amplifiers and use many of them, especially during this period in the sunspot cycle. An amplifier is a great tool when used for the correct job.

In this specific circumstance, he can get more db per dollar by replacing 100ft of rg58 and using a directional antenna. If he changes all of those, and still needs a little more, then go for the amp, but fix the cheap stuff first.

$300 can buy you at least 10-11db in this case (LMR 400, and moderate size yagi)...you can't touch a 2m amp or homebrew one with that much gain for the same $$.
444  [Team Member]
12/13/2007 9:28:19 AM EST
As I stated in both of my previous posts, I openly advocated improving the antenna system. No where did I say this wasn't a good idea.
B U T: you are making a number of assumptions to prove your point that may or may not be true. First of all, CAN he put up a directional antenna ? Probably, he can, BUT he never said that. Not everyone can simply put up any antenna they desire: I am one of those people. He might be also, I don't know. By just making the blanket statement that your option is the only correct decision is dismissing the possibility that his circumstances arn't the same as yours. Again, using me as an example: no matter how much better my signal might be with a beam and different feedline, I can't put one up legally. No matter how many db/$ it is going to produce, I simply can't legally put one up. This probably doesn't apply to him, but it could. I feel certain that I can not work simplex stations on 2m FM at the distance of 150 miles from my house simply because I can't put up an adequtate antenna. BUT, if I wanted to try, the only thing I could do would be to increase my power. Not because the is nessessarily the cheapest option or even the best option. It would be the only option for me. For Scott ? I don't know. Hopefully he can put up a beam at 200 feet, run hardline to it and pump it full of power at the legal limit.
The second assumption that you make is that he isn't going to improve his station throughout from the microphone through the antenna and everything in between. He asked about amplifiers. The fact that he asked about amplifiers doesn't mean that he can't ALSO improve the rest of his station AND buy/use an amplifer. Since he posted the thread and specifically asked about amplifiers, I thought at least one person that answers him should discuss amplifiers. Call me crazy.
And, since I am repeating myself I will again repeat the fact that if you want to consistantly work someone on 2 meters simplex from 150 miles away, you are going to need more than a beam, more than changing you transmission line, and more than an amplifier. You are going to need to do all three. The entire system needs to be as good as can resonably be achieved. The system consists of many parts. The part asked about was the amp.
Gamma762  [Team Member]
12/13/2007 9:44:58 AM EST
Better antenna and especially feedline will make a tremendous difference in your communications efficiency. You're probably losing 6dB or more in the RG58+barrel connector feedline versus LMR400 for example (and WAY more loss if you've got water in that barrel connection and into the feedline). 6' to 10' fiberglass antenna would get you another 4-6dB. You shouldn't even be thinking about an amplifier until you get these basics out of the way, realize that just changing your feedline would be the equivalent of going from 50w to 200+ watts AT BOTH ENDS of the conversation. Also remember that big VHF amplifiers require big DC power supplies which are expensive as well.

If you have a fixed location you need to communicate with then a fixed yagi pointed at that location is very effective, but for general use a yagi with a rotator and everything adds a lot of complexity.

The difference between a 30' tower and a 50' tower isn't going to matter much at 150 miles unless you're getting above local obstructions near your tower site (buildings, trees, etc).

For general purpose amateur communications, VHF amplifiers are not the way to go IMO. If you have a reasonably efficient system and can't maintain reliable communications, pick an alternate transmission mode or frequency band. NVIS works very well at 150 miles for example. You also might be very surprised what kind of range you can get from very high gain 440MHz yagis which are a more reasonable size than VHF yagis. Going to 2m SSB instead of FM will also increase your link margin quite a bit.
ThePrepared_com  [Team Member]
12/13/2007 3:49:55 PM EST

Originally Posted By Gamma762:
Better antenna and especially feedline will make a tremendous difference in your communications efficiency. You're probably losing 6dB or more in the RG58+barrel connector feedline versus LMR400 for example (and WAY more loss if you've got water in that barrel connection and into the feedline). 6' to 10' fiberglass antenna would get you another 4-6dB. You shouldn't even be thinking about an amplifier until you get these basics out of the way, realize that just changing your feedline would be the equivalent of going from 50w to 200+ watts AT BOTH ENDS of the conversation. Also remember that big VHF amplifiers require big DC power supplies which are expensive as well.

If you have a fixed location you need to communicate with then a fixed yagi pointed at that location is very effective, but for general use a yagi with a rotator and everything adds a lot of complexity.

The difference between a 30' tower and a 50' tower isn't going to matter much at 150 miles unless you're getting above local obstructions near your tower site (buildings, trees, etc).

For general purpose amateur communications, VHF amplifiers are not the way to go IMO. If you have a reasonably efficient system and can't maintain reliable communications, pick an alternate transmission mode or frequency band. NVIS works very well at 150 miles for example. You also might be very surprised what kind of range you can get from very high gain 440MHz yagis which are a more reasonable size than VHF yagis. Going to 2m SSB instead of FM will also increase your link margin quite a bit.


Can you recommend a 2 Meter fiberglass antenna like you mentioned above?

I have lots of antennas made for NVIS just haven't had the money for HF gear.

--Scott
Cyclic  [Member]
12/13/2007 4:31:53 PM EST
Height and antenna, then go for power.

I'm using a 5 watt max HT, about 35 feet of RG58, a 20 foot tower(clears the house but not the trees in the direction of the repeater), and a home brew vertical di-pole. I get about 15 miles cleanly, and 20 on a good quite night. I can go down to 0.5 watts and still cleanly hit the repeater 3 miles away even through the trees. Its all about the antenna and the height.
444  [Team Member]
12/15/2007 2:16:28 PM EST
In honor of this thread I bought a Mirage 2 meter amp. 10watts in, 160watts out.
Got a good deal, used.

It is a substitute for my manhood.
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