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Author Topic: amp for IC-705  (Read 1075 times)

WB6BYU

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Re: amp for IC-705
« Reply #15 on: July 27, 2021, 03:09:01 PM »

Quote from: KD2HPQ

...I'm going to look into an efficient, resonant antennas for 40-20 and whatever else is possible. But even that is a lot of wire...



It depends where you are operating and what you expect.

I've operated QRP over the years from many different locations.
Mostly I carried a dipole kit in my backpack that I could configure
for any combination of 80, 40, 20, 15 and 10m.  (My rigs at the
time didn't cover the WARC bands.)

The only time I remember that I wanted to set up an antenna
and couldn't was while riding a train for a couple days across
Australia.

Granted, the dipoles weren't always set up in textbook manner,
and occasionally the wires were converted into other sorts of
antennas as circumstances permitted or required.  And sometimes
it didn't work very well, like the wire tossed out the hotel window
in Alaska, with a coat hanger bent into a grappling hook to catch
the rain gutter across the alley.

But, at least for my style of camping, finding space wasn't a
problem in any of the campgrounds I remember.

And overall the antenna worked pretty well... but I often
used CW instead of SSB.




Quote

One of the cruelest statements ever made by a ham is, "just throw a wire into a tree." At 5 or 10w it had better be a very high-performing wire indeed.



An end-fed wire isn't as simple as an antenna as it might
appear at first glance.   You need to consider the ground
system, often a tuner, and whether the radiation pattern
is optimum for the desired communications.  Many of
the implementations are more suitable for running 100W,
where even a 10% efficient antenna radiates more power
than my dipole does at 5 watts.  (Unfortunately, some
antennas advertised for QRP are more "cute" than efficient.)

That's not to say that an end-fed wire can't work well - it
certainly can.  But it can also be pretty useless, and the
secret is understanding to know how best to optimize it
for your desired communications.  I've used both types,
and that is why I ended up with the dipoles.

KU3X

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Re: amp for IC-705
« Reply #16 on: July 28, 2021, 07:56:27 AM »



.......An amplifier can make up for a crappy antenna, sometimes.


Allison

That is one statement I could not DISAGREE more with. If you can't hear them you can't work them no matter how much power you run !
I teach everybody that shows an interest in the hobby, "Focus on you antenna first."

On my 40 meter mobile system, I was able to increase my signal by 8 DB just by fabricating a better antenna. That's 8 DB of transmit and receive. If I added a solid state amp to increase my transmit it would cost me about 75 additional amp of current drain on the car's electrical system......and....it would not help me on receive.

Barry, KU3X
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KH2BR

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Re: amp for IC-705
« Reply #17 on: August 11, 2021, 10:37:23 AM »

I have a new IC-705 also and in the past have been looking at all the rigs that I own. None of them are suitable to take out in the field due to the high current consumption in only receive. I found a solution to a small amplifier to take with me when I go to the parks or beach.
The amplifier that I use is a Juma PA-100D. The standby current without transmitting is only 100 milliamps.
You can find them at www.jumaradio.com. You can buy them at rowaves.com for over 500 Euro. If you don't want to spend that kind of money,
Jumaradio.com has provided gerber files that you can download and send off to www.pcbway.com. I had some PCB's made and only took 10 days to get them for a juma receiver I wanted to build. Cost about $3 a board so I ordered a lot of them. I am building my shopping list at Digikey for the receiver and getting the IC's from china on ebay.
Other kit amps might work also but I do not know the current consumption of them when not transmitting.
I was thinking a long time ago about selling the Juma, I am sure happy I still have it !!  Its a real good amp. !!!
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K0UA

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Re: amp for IC-705
« Reply #18 on: August 11, 2021, 10:52:07 AM »

I have a new IC-705 also and in the past have been looking at all the rigs that I own. None of them are suitable to take out in the field due to the high current consumption in only receive. I found a solution to a small amplifier to take with me when I go to the parks or beach.
The amplifier that I use is a Juma PA-100D. The standby current without transmitting is only 100 milliamps.
You can find them at www.jumaradio.com. You can buy them at rowaves.com for over 500 Euro. If you don't want to spend that kind of money,
Jumaradio.com has provided gerber files that you can download and send off to www.pcbway.com. I had some PCB's made and only took 10 days to get them for a juma receiver I wanted to build. Cost about $3 a board so I ordered a lot of them. I am building my shopping list at Digikey for the receiver and getting the IC's from china on ebay.
Other kit amps might work also but I do not know the current consumption of them when not transmitting.
I was thinking a long time ago about selling the Juma, I am sure happy I still have it !!  Its a real good amp. !!!

That looks really nice, and Juma's have a reputation for reliability
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73  James K0UA

VA3VF

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Re: amp for IC-705
« Reply #19 on: August 11, 2021, 11:55:39 AM »

Quote
...and getting the IC's from china on ebay.

Make sure it's a reputable vendor. Counterfeits, seconds, and pulls abound.
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KB1GMX

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Re: amp for IC-705
« Reply #20 on: August 11, 2021, 12:35:13 PM »

Barry,

If your hunting for argument... not going to get it here.
That's why there was ", sometimes." at the end.

The cheapest amplifier is a good antenna or a beam.
FT817 into a tribander, effective.

There are cases where the antenna hears well enough but a bit more
power really does help.

Me: antennas are cheap,  amps not often cheap.

Allison
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W1VT

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Re: amp for IC-705
« Reply #21 on: August 11, 2021, 12:58:09 PM »

I ran 4 watts to a 2 element Quad in 1986 and got out great from Hawaii.
I could call CQ and raise Australians on 10 meters. 
They could easily find me as there were few competing signals on the band.
CQing was less productive during the Sunspot peak has I'd get lost in the activity.

Zak W1VT
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VA3VF

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Re: amp for IC-705
« Reply #22 on: August 11, 2021, 01:01:49 PM »

Quote
The cheapest amplifier is a good antenna...

Exactly. No point pumping more power into a "dummy load".
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KH2BR

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Re: amp for IC-705
« Reply #23 on: August 11, 2021, 03:00:34 PM »

In his first post, He wants to take his radio out into the field, sorta of like POTA, SOTA etc..  Big beams or quads are impractical if he is doing that. He will need the best location and best wire antenna and a way to get people looking for him due to the diminished day time operations we have now.
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W9IQ

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Re: amp for IC-705
« Reply #24 on: August 11, 2021, 03:23:33 PM »

The suggestions of antenna gain are nice but the reality is that you will not get 7 to 10 dB of gain from optimizing some portable antenna kit. Add to that the higher noise floor of the typical receiving station and you cannot get there. Buy the amp and get heard.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KB1GMX

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Re: amp for IC-705
« Reply #25 on: August 12, 2021, 01:16:06 PM »

While a beam or other large antenna is far from portable
(unless VHF maybe) a dipole is still a good antenna and
getting it high as possible makes a difference.

So for portable while often times convenient a loaded
vertical is andy but performance is most at typical sizes
I've seen are low efficiency.

End fed half waves are useful for portable work if you
have trees or other high things that support one end.

I have enough experience running 100W into short or
otherwise inefficient antennas to say its frustrating. 

Power doesn't fix a poor antenna, rarely offsets it.
Where it really helps is pileups, its then a matter of
 being heard over the guys with 400-1500W.

Allison
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K0UA

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Re: amp for IC-705
« Reply #26 on: August 15, 2021, 04:50:29 PM »

I can tell you this much, running 5 watts portable into poor antennas like my end fed "random" wire with 9 to 1 UNUN is day and night difference to running the same exact antenna at 100 watts with my Yaesu FT-891.  Day and Night in favor of the 100 watts. And you can take that to the bank. Not that you can't make contacts on SSB even with the 5 watts, because I have done it. But you can make a heck of a lot more with 100 watts. Just 13 dB makes the difference in "I hear a little something in there, to Ok K0UA, you are 55".
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73  James K0UA

WB6BYU

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Re: amp for IC-705
« Reply #27 on: August 16, 2021, 06:42:36 PM »

Quote from: W9IQ

...the reality is that you will not get 7 to 10 dB of gain from optimizing some portable antenna kit...




I don't know - some of the antennas and kits advertised for
"portable" operation are so poor that you probably can
get 7 to 10 dB improvement!  And the result may be lighter
and cheaper as well.

Actual examples that come to mind include a "hamstick
dipole" (on 40m and 80m) and one of the cute tunable
small verticals where the instructions said to cut your
radial to 1/4 wavelength and wad it up in the bottom of
your backpack.  Both came to me because the owner
couldn't even get them to tune, let alone radiate efficiently.

In another case, two ARES units showed up for an event
on the county line, and checked into the state-wide 75m
net with the same signal strength.  But one was using
100W to a vertical, and the other an FT-817 to a dipole.

So, yes, some antennas really are that bad!

KU3X

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Re: amp for IC-705
« Reply #28 on: September 02, 2021, 08:12:56 AM »

Barry,

If your hunting for argument... not going to get it here..............


Allison

Argument? Not me.  Just trying to share useful information. I just pointed out that with a little creativity you can increase your ERP and not consume more current off of one's power supply.
Am I suggesting someone erect a beam antenna when they set up portable? No way, but they can if they choose to do so. My one friend does. I don't know if the Buddy Pole guy makes it, but it's in a nice tidy little nylon carry case.
I've erected a 40 meter delta loop portable. Just toss a rope over a tree limb and hoist the apex in the air. Surely that will work a lot better than what I point out next......

Go look at some youtube videos and look at what some hams are using. I watched one video where the guy is using a 23 foot non resonant antenna, feedpoint laying on the ground and the other end sloped to a tree tied off at 15 feet. He said there is gain off the end of the antenna with the signal going off the end like an arrow. The next video is a ham using again a 23 foot non resonant antenna and using his ATU to get on 80 meters. "Look how good this antenna is", he said. NO, look how good your ATU is ! What's his ERP. I've even seen where one ham tried to use his ATU to get, again....the same antenna, on 160 meters.

Does 100 watts generate more Q's than 5 watts? Surely the answer is YES.
Does 1500 watts generate more Q's than 100 watts? Do I have to answer?

I'm just pointing out that the antenna is your first line of defense. Focus on erecting a good antenna, not some junk and then using an amp to try to overcome your poorly designed and/or erected antenna.
With my 40 meter beam at 83 feet, aiming in the wrong direction, I can still hear stations on it that I can not hear on my wire antenna at 40 feet. How will an amp help me work the ham I can hear on my beam but not my wire antenna?

If one wants to carry an amp portable along with one heavy battery, have at it. For me, my battery fits in my back pocket and I can work all day in the park. If it's not someone on the other end running 1500 watts or a major pileup, with my 5 watts, if I can hear them I can work them.

I am not going to belabor this topic. It was not posted to generate an argument. I will let that up to you to do so.

Barry, KU3X
« Last Edit: September 02, 2021, 08:18:52 AM by KU3X »
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KB1GMX

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Re: amp for IC-705
« Reply #29 on: September 04, 2021, 06:16:00 PM »

Barry,

I like running QRP to me 100W is serious QRO as that the most
I can make on HF.

Most of the time FT817 or other monoband rig of which i have many.
Over the years I've had people tell me you can't do that while I was doing it.

So first and foremost its about the antenna.  More power in to a
good antenna gets better results but portable may dictate other conditions.
My standing favorite is end fed half wave for RF-40/20/10 the PAR unit.
Backup is vertical as tall as I can make it 10-16ft as its then easier to
feed and more efficient.

I've seen people do Buddypole Beams, they work very well.  It can
be very compact.

However the one thing is clear, if you do not do it, it will not happen.
Sometimes a bit of faith and persistence and your off having fun.

I go out to have fun so the general rule applies.  A bad day fishing
is better than a good day at work (likely exceptions to that even.).


Allison
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