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Author Topic: amp for IC-705  (Read 1074 times)

N8AUC

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Re: amp for IC-705
« Reply #30 on: September 04, 2021, 08:03:50 PM »

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!

So true! Been there, done that.

We were doing an ARES field exercise about 4 years ago.
Objective was to setup in the field quickly, and make contact with the state EOC (120 miles away).
One of our guys had a 100W rig into a homebrew end fed. Mainly, the antenna was built wrong.
Wire too short, 9:1 UnUn was wound incorrectly, no counterpoise, etc. Used a tuner to get a 1:1 match.
He could hear the state EOC just fine. But try as he might, they couldn't hear him.

I fired up an FT-817 on SSB with a 7Ah AGM battery into a resonant dipole at 15 feet, and got a 5 x 8
report from the EOC on the first call. Yeah, I know it was a cloud warmer, but NVIS was the objective.
The other guys still talk about how steam was shooting out of the ears of the guy with the 100w rig.

Moral of the story....your antenna MATTERS....and it usually matters more than your power level!
« Last Edit: September 04, 2021, 08:06:48 PM by N8AUC »
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KM1H

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Re: amp for IC-705
« Reply #31 on: September 05, 2021, 04:55:27 PM »

If available and working well a good sleeper amp is the Heathkit SB-230 with the 8873 final, it should be capable of up to 300-400W out with that drive and can easily do a lot less.

The tube is fairly fragile and near unobtainium but when run sanely it is just an 8874 with a big aluminum heat sink for the anode and less rated dissipation. Since it uses the same plate choke as the SB-200 and 220 family it works well on 17 and 12M with no input tuning since power is fed to several carbon resistors. I have one I converted to 6M decades ago as a rover or for vacation house; still puts out 600W.

Carl
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AB7R

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Re: amp for IC-705
« Reply #32 on: April 04, 2022, 10:41:51 AM »

Don't discount the hardrock-50.  I found one with the builtin tuner for a good price.  Hobbypcb also makes a bluetooth interface box to send band data to the amp.
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GRUMPY2021

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Re: amp for IC-705
« Reply #33 on: April 04, 2022, 12:01:58 PM »

Also remember if you are an S-9 with 100 watts,  25 watts will be an S-8 and 6.25 watts will be S-7...your QRP is more capable than you think.   I also vote for a better antenna.   2 cents.
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KQ4KK

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Re: amp for IC-705
« Reply #34 on: April 04, 2022, 12:57:33 PM »

To answer your question directly. A Hardrock 50 will give you about 50 watts out. Takes about 8-10 amps. Take a BioEno 13vdc, 10 amp battery.

Other 100 watt amps- XEIGU XPA 125B or ELECRAFT KXPA 100. They will draw about 12-20 amps. The KXPA 100 is a Beautyful amp, but will draw lots of $s from your wallet.
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HAMHOCK75

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Re: amp for IC-705
« Reply #35 on: April 05, 2022, 03:11:46 PM »

I sold a Yaesu FT-897D to buy a 705. The 897D did have some features normally not available on most 100 watt rigs. It was designed for field operation with its own internal battery pack so the squelched receive current was 600 mA. If powered by the internal battery pack, the output power was limited to 20 watts, but running off an external DC power supply or the FP30 internal AC supply, it was capable of 100 watts output.

LIke the 705, it covers 160 M through 70 cm.

https://www.yaesu.com/downloadFile.cfm?FileID=7592&FileCatID=158&FileName=FT%2D897D%5FOM%5FENG%5FEH012M105.pdf&FileContentType=application%2Fpdf
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AE5X

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Re: amp for IC-705
« Reply #36 on: April 13, 2022, 01:05:18 PM »

I joked recently about a "705 Companion" but I wouldn't be surprised if Icom actually does eventually offer an amp designed specifically for the 705 - with built-in autotuner of course.

https://ae5x.blogspot.com/2022/04/icom-releases-705-companion.html

The 705 was new territory for them and we're debating all kinds of amps for it except an Icom-branded one. I'll bet they'd sell like hotcakes.
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AF5CC

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Re: amp for IC-705
« Reply #37 on: April 15, 2022, 11:30:01 AM »

What does the QLF button do on the 705 companion?  I do know what QLF means!

73 John AF5CC
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AE5X

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Re: amp for IC-705
« Reply #38 on: April 17, 2022, 05:57:21 AM »

What does the QLF button do on the 705 companion?  I do know what QLF means!

73 John AF5CC

"Are you sending CW with your left foot?"

The button allows the Companion to emulate poorly sent CW.
« Last Edit: April 17, 2022, 06:01:04 AM by AE5X »
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KH6AQ

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Re: amp for IC-705
« Reply #39 on: April 18, 2022, 10:54:24 AM »

There is an IC-745 100W PA for sale here on eham for $90. The ad says it's plug and play.
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KB1GMX

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Re: amp for IC-705
« Reply #40 on: April 25, 2022, 01:15:59 PM »

Its about the antenna. 

Power helps but if its in a pack your back may complain.

Antennas that are small physically are less efficient as physics
always wins.  They be ok if they trade bandwidth for efficiency
and that's not an operating inconvenience.

HF the PAR EF40/20/10 is the goto t 40ft long.  Light and compact. I've used
it on every band from 60M though 10M with wires cut for 60, 17 and 12M
handy in the kit.  It takes 25W continuous so even the 100W rig throttled to
50W SSB is reasonable.  That antenna, spare wires and 25ft or RG58 is
under 2 pounds.  Add ropes and all maybe 4-5 pounds.   Still installation
and height are the key elements.  That varies with the known or expected
limits of the location.  I have a kit for vertical and height (of the element)
is everything as its going to be less efficient than dipole or EFHW.

I do have a small HF only (80-10M) 100W brick.  At 13V it eats a nice 16A
 (for 60W) on peaks along with the radio at 2A s its not much better than
the average 100W radio.  Until I turn the amp off, and 2A (ft817 peaks)
looks good.  It they heard me with the 60W then they will hear me with
5W unless their antenna is very poor (or they are in noisy location).  Either
 case experience taught me that its about the antenna.  So anything
close to a tuned dipole (or EndFed Half Wave) at reasonable height is
game on. 

IF the site and all allow a wagon or cart to transport it all, you can get
the bigger stuff to the working position like 100W, big battery, maybe
solar charging, are a easy thing.  Still a good antenna makes contacts
easy then.  Field day is a good example.

FYI  the 1:9 fed random wires are rarely the same performance level as
a tuned half wave anything (Dipole or EFHW) until the wire starts to be
long as in 53ft for 40M and 84ft for 80/75M) Which is nearly a half wave
on those bands plus it requires a tuner!  They require a counterpoise and
all the setup rules (height and supports) as any other decent antenna.

Despite all that said.. First rule is best antenna possible, and active band,
and the attitude I can be heard.   A little persistence helps.  Generally once
the first or second contact is made there will be people actively hunting for you..
Best way to get that, POTA, SOTA, IOTA.

HINT: you want a signal that attracts attention of the positive kind.
That being clean, crisp, no background noises, and no undesired
artifacts.  Do not overdrive the rig or have a setup with RF in the
audio issues. It degrades the signal and often will get you passed
over as its too difficult to copy.   Same for CW, poor keying, chirpy,
or a bad fist (less common) can lower responses.


Allison
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