Opinions on this amp for FT818?

Any thoughts about adding this to the FT818 VHF SOTA tool kit? The amp would be used on short-hike difficult VHF circumstance summits and in conjunction with the FT818 as a home base



I have used Daiwa and Radio Shack amps to increase the output power for mobile or base use with great success on vhf.

I have also done that on HF with several brands of amps and again it works great.

To make pack out easier I have started using the 857D as a SOTA and VHF/UHF contest radio because it offers similar power output if I need it across all the bands and modes.

However, there is a lot to be said about the ability to have a modular set up.

A gain antenna (a Yagi) is lighter, costs less, and might just be as good as an amplifier on 2M. Something like an Arrow yagi…

An amp lets other people hear u better. An amp doesn’t help you hear them any louder like a gain antenna would. You might want to upscale your antenna first?



I like the Yagi idea. I actually do have a arrow Yagi but have not used it yet.

So this may be a obvious question. When conducting SOTA activations with the Yagi do you make calls in a 360 degree pattern stopping at each, say 30 degree spot in the circle around you for a minute or so waiting for an answer, Or just aim for populated areas?

@KE8OKM Yes please…360 degree pattern. I’ve often prayed for the activator to swing the beam around in my direction. You never know it might be the contact you need to qualify the summit.

73 Allan

I always try to include my general location in my CQ calls. I have had several chasers say that helped with locating me with their Super Yagis!

I am going to try the Yagi out before I spend more money on amps.

Thanks for the thoughts and ideas!

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Also put in an ALERT and let people know you will be on a summit. This is a big deal to success on VHF.


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Hi Erik,
If you have the battery capacity an amp might be good. The RF amp isn’t as good as I would expect. A 1.5 dB NF or better should be standard.
Otherwise it provides no help to a rig less than 15 YO. A generalisation of course but if you are going to be louder it would be good to hear better.

Re beam, I used to point to several known activity areas. The beam wasn’t so sharp as to prevent me hearing and being heard 45 degrees off axis. Also the rear lobes often are not so far down and can alert people to your presence. You can swing the beam on them when they call

Good luck.


I agree with the alert notification. In SOTA active areas (Colorado,Wyoming,Arizona, California etc) alerts have been productive in obtaining contacts. In the Midwest of the USA SOTA or at least VHF SOTA chasing is much less common, add to that almost “0” activity on simplex and it becomes quite frustrating😂 but still beats a day at work!

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I would go first for the yagi for sure, but I want to point out the importance of the receive pre-amplifier on the amp. An amp like this isn’t just about getting louder, it is also about hearing better.

Chances are when you connect your 818 to your antenna if the background noise level is not enough to move your s-meter you may be able to benefit from a receive preamplifier. Noise levels can be really low on a summit so these are sometimes good places for preamps. A good preamp in the right conditions will take someone you can tell is there but can’t understand and turn it into a contact you can make.

I know my 817 and 706MKIIG are not particularly sensitive on 2m and are somewhat deaf on 70cm regardless of what the official stats say and they benefit from external mast mounted preamps on summits. 706MKIIG’s built in preamp simply isnt enough.

So definitely improve your antenna first (improve gain AND height --benefit to get above treetops), then examine your coax with a proper analyzer for loss and replace if necessary, then get an amplifier with a preamplifier as the final step.

I was shocked to see my RG-58 way out of spec on 2m when checked for loss with the MFJ analyzer. I had mistreated my RG-58 for too long (tight wrapping circles on a well known wire wrapper). I gained more than 3 db of signal on receive and TX just by moving to new and slightly larger coax.

If you want to go completely crazy, get a mast mounted preamplifier right by the yagi above the treetops AND a power amplifier by your rig on the ground. Oh and go to something like LMR-600UF for coax if your run is like 50 feet. Of course this all weighs allot!

As a final word, in the US at least on 2m SSB you can pretty much count on the station at home to be running something monstrous…if you can get your antenna above the treetops and the chasers know to look for you they will turn their massive array your way and blow you away regardless of what you are running. I worked K1TEO once on 2m SSB from a summit in Connecticut WHEN I HAD FORGOTTEN TO CONNECT THE COAX TO THE RADIO. He worked me with no antenna on my 817 during the ARRL VHF contest. Who knew all that coax and antennas were actually unnecessary :slight_smile:

Tom, N2YTF

Tom thanks for taking the time to write that! I find it challenging in a good way trying to pull off these difficult VHF activations. Especially in SOTA sparse areas! 

Today I set up my FT60R with a Rollup-Jpole (as high as I could climb a tree safely to hang antenna ~20’ off ground) on W3/ER-001 in Western Pennsylvania. My FT818 Arrow Yagi is back in Colorado if I had it, I would have tried 2M SSB. The “summit” is at 1630’ above sea level and about 3-400’ above surrounding terrain. I have tried to activate this summit twice now with about 3hrs of calling CQ. I have received “0” simplex QSO’s. The interesting thing is I can easily reach 2 repeaters. One 50 miles and another 22 miles away with very good tx and rx reports. I had several hams try to work me switching over to simplex but no call received?

So I have several theories on why no QSOs are to be found!

  1. No one monitoring simplex. And the couple that attempted just in bad spots.
  2. Antenna is too low.
  3. Heavy foliage? But I’m thinking it wouldn’t get to the repeaters if that’s the case?

I think next time I try this one. I am going to launch the Jpole much higher 50-70’ has anyone tried hanging an antenna from balloons? And bring Yagi
And get it high.

Beautiful Fall afternoon in Western Pennsylvania!

Out here in rare SOTA land (I have to explain what I am trying to accomplish) I am thinking monitoring simplex is not as common as in very mountainous areas. I have encountered a couple hams while calling to repeaters asking to kindly listen for me on simplex and I am met with “ I don’t think my radio can do that”, “I just got this radio and can’t tune that frequency”, “what is simplex frequency?” I think most are genuinely happy to be making a QSO and learning about what SOTA is AND more importantly that you can get outside to experiment with radios!

About trees? I have read that it should inhibit tx/rx. I have activated several heavily treed summits and foliage has had “0” impact as far as I can tell.



They do have an effect. The clearest illustration for me was back in about 1968 on 70 cms. There was a station that I regularly contacted in the winter but as the trees came into bud near him his signal became weaker and after a few weeks he vanished until the fall. The path between us passed over a ridge covered in trees. This happened every year. I know it happens on 2m too, but it is difficult to quantify because of the underlying variation in conditions. There are a lot of ancient trees in my locality, including some oaks that I estimate are 400+ years old, and I estimate that they cost me several dB in the months when the sap is rising. You won’t notice the effect on a good strong signal, only on the weak ones.

Good to know! I hope to see what the difference is when the leaves fall and also with snow on ground.


The effects of trees whether in leaf or not on the radiation of signals is very much frequency dependant . I have used them to support aerials and have installed aerials in the actual trees themselves as vertical ground wave or as inverted L antennas for many years, albeit for frequencies 1.8 - 14 MHz, where they have been very effective I believe - with little attenuation of my signals due to the presence of the trees. In Europe I have operated for SOTA on HF in many woodlands and made 100s if not 1000s of contacts.

On VHF and UHF it is a different story - I am sure there would be some attenuation of signals but I do not know of any study which has been conducted to prove this.

73 Phil G4OBK

There’s lots of research onto foliage effects on RF propagation




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Thanks Andy - most studies listed look at losses in forests, some equatorial forests in fact. Many references quoted in the first link relate to IEEE documents which are not available as free to read documents online unfortunately. The second link doesn’t work for me.In the PDF the main interest is more suited to the sort of freqs you use on summits UHF / Satellite. I know of people who have had to chop trees down to get a watchable TV signal into their Sky dish, or find that in summer they get picture breakup due to leaf cover.

Information about the use of tree mounted aerials in the frequency range 1 MHz - 10 MHz is what I would find most of interest, as the three aerials I use in this range of freqs are mounted in a single tree in my garden.

73 Phil

I think one of those docs had someone’s formula for HF in it when I had quick look. But UHF and up is where the losses will be more apparent.

A poet on trees

From ‘Binsey Poplars’, by Gerard Manley Hopkins

My aspens dear, whose airy cages quelled,
Quelled or quenched in leaves the leaping sun,
All felled, felled, are all felled;
Of a fresh and following folded rank
Not spared, not one
That dandled a sandalled
Shadow that swam or sank
On meadow and river and wind-wandering weed-winding bank.

An artist on trees

Van Gogh, Mulberry Tree

A physicist on trees:

From Rec. ITU-R P.833-9




I didn’t really believe in 2m/70cm tree attenuation until I experimented on w2/gc-002 Hunter Mtn a few years ago. There is a fire tower on hunter that rises above the dense treetops. I tried 2m and 70cm from the tower with a beam below and above the treetops and the difference esp on 70cm was dramatic. Previously I had always had trouble in 2m there from ground level.

Be sure you try 2m during busy periods (typically weekends) and get a voice keyer. I use the bx-184 built into my 817’s mike. Folks are out there—some with giant beams-but you need to call like a madman. In part this gives them time to beam at you. Also post ahead of time to the many 146.52 Facebook groups. Nothing is as nice as going up a hard summit and getting hungry, setting the 817 calling on 2m, and immediately having a sandwich while I wait for that first contact—a voice keyer can give you that.

There are also regional 2m ssb nets —look for one in your neck of the woods if you have ssb

I have had trouble on 2m simplex from isolated areas. Today though I went up w2/gc-055 about 30 miles north of NYC. There was 146.52 activity for most of my hike and as I approached the summit I heard two guys talking about looking for SOTA people even before I called.

I would caution about tree mounting the Jpole if it means using lossy coax. Check your attenuation stats for the length and size you are using and remember a 3db loss means half of your power on tx and rx is gone.

A beam (home brew or perhaps diamond as they are light) on a mast is a nice setup. Gigaparts now has carbon fiber masts that can support a yagi no problem but they are costly. They even have a pricy 50footer. There are a million other masts that can do the job also.

Tom, N2YTF

Tell them it’s a repeater with the same offset as the one you’re on, give them the simplex frequency as if it’s the output and then listen for their replies on the “input”. If they transmit out of band, the FCC will help them understand how to configure their radios properly, and if not, some band cop will come up and do the same.