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Author Topic: Recommended Antenna Tuner for QRP output power around 200 mW?  (Read 459 times)

KG4LAC

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Recommended Antenna Tuner for QRP output power around 200 mW?
« on: August 26, 2022, 06:59:49 PM »

Any recommendations of an antenna tuner for QRP output power around 200 mW?

Thanks.
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WB6BYU

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #1 on: August 26, 2022, 09:08:38 PM »

What type of antenna are you trying to match?

Other than having a sensitive enough meter that you can read the
SWR, any tuner should handle that power level.   Some "QRP tuners"
are relatively inefficient, because it is more difficult to notice the
losses at low power.  (The coil doesn't get hot enough to melt the
plastic supports, for example, which can happen well below the
rated power level of a higher power tuner.)

Generally, I'd choose my tuner based on the impedance I need to
match, and other operating requirements.  Often I use a "300W"
class tuner, or larger, and pay attention to how I adjust it to
maintain good efficiency.  For an end-fed wire that is over about
3/8 wavelength long, I generally just use a simple L network
with one coil and one capacitor.  For balanced antennas, I had good
luck with the old Ten-Tec AC-5, and am thinking of building one
on a similar design.


So perhaps you can provide more information to help us help you.
In addition to "what antenna", things like the bands you want to
cover, physical constraints (size and weight limits?), whether it
needs to have a built-in SWR indicator, if you want it to be
automatic, balanced or single-ended output, etc.

K6SDW

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #2 on: August 26, 2022, 09:48:44 PM »

I'd say a simple manual tuner with LED power output indicator...simple. QRPGuys has a nice kit which I built and works great.

Not into kit building MFJ has a few manual tuners you might find interesting. I also have an older MFJ tuner with meter display which works FB.

I've never owned one but Elecraft sells their T1 20watt max auto tuner and I've heard good things about it. However, very pricey!!

200mW....you must like a challenge. HI HI

GL/73
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N8NK

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #3 on: August 27, 2022, 02:00:08 AM »

...
200mW....you must like a challenge. HI HI
GL/73
200 really IS a challenge. But then again, I've worked southern Artentina using 2.5mw on 15m and carried on a half hour rag chew with the fellow QRPer.
Care for the story anyone? Please see 'A QRP Story' at https://youtu.be/ja6e_uISvZ8
Chuck
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KG4LAC

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #4 on: August 27, 2022, 07:31:01 AM »

Maybe an swr bridge is better for such low power?

I'll be running WSPR as per the September 2022 QST "ZachTek WSPR Desktop Transmitter" article on pages 44 thru 46.
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N8TGQ

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #5 on: August 27, 2022, 04:22:52 PM »

 I just got one of Zachtech's CW flea transmitters that puts out around 300 mw.

My MFJ 971 tuner matched it to a 29' random wire no problem on 20, 30 and 40 m. I had output power and SWR readings on the meters.

I was just testing to make sure it was working when I got it. Now its stashed away to keep me busy when winter gets here.

i think the output of these little guys is pretty tolerant of high SWR. It would be tough to get 1 antenna that will match on all the bands the WSPR units can run on. Zachtech has a forum set up on their website. You might try asking over there. Zach is pretty quick to answer questions.

You might consider an end-fed half-wave antenna cut for 80 meters. That way your SWR would be close on all HF bands except 60m.
« Last Edit: August 27, 2022, 04:30:52 PM by N8TGQ »
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WB6BYU

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #6 on: August 27, 2022, 04:50:11 PM »

You might review this thread, and at least one or two more that came
before it by the same poster.

They include the effect of adding an antenna tuner to the Zachtech
transmitter, as well as various types of antennas with comparison
results.

KG4LAC

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #7 on: August 28, 2022, 04:57:08 AM »

Thanks!
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KC8SBV

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #8 on: October 23, 2022, 04:53:48 PM »

The meter might do what you need, follow it by any tuner you have handy, and you should be good to go

https://www.tindie.com/products/NM0S_qrp/qrpometer/
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KG4LAC

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #9 on: October 26, 2022, 02:30:36 PM »

Replaced the coax going to the 4:1 balun over the past weekend including a soldered PL-259. Must have done things correctly as my 0.2 watt signal is being received in Antarctica!

Looking forward to receiving and using the QDX 4-band 5W Digi transceiver.
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VK3YE

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #10 on: October 29, 2022, 01:29:43 PM »

Any recommendations of an antenna tuner for QRP output power around 200 mW?


Many ideas on my website at: https://vk3ye.com/projects/projcoupler.htm
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KC3TEC

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #11 on: November 12, 2022, 11:15:11 AM »

The matchstick tuner kit from breadboard radios is great for that
I have one and i love it.
Size wise its about 2 inches by 2 inches by 1 inch high so it doesnt take up a lot of space.
Hes retired now so i dont know how many kits he has left.
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KG4LAC

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #12 on: November 12, 2022, 03:07:11 PM »

Thanks, but since my OP, I don't need.
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KB1GMX

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #13 on: November 15, 2022, 08:39:15 AM »

At 200mW wasting power is a bad idea. 
Best suggestion is a matched antenna.

Adding a tuner consumes power, if the mismatch is great
enough your wasting power in the feed system (coax?).


Allison
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KG4LAC

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Re: Recommended Antenna Tuner for QRP output power around 200 mW?
« Reply #14 on: November 16, 2022, 03:10:16 PM »

Being heard in Australia, Hawaii, Artic Circle and Antarctica. Don't believe much power, if any, is being wasted.

I understand the theory of proper matching. However, in an attempt to perfect our setup, we never actually get on the air?

Reminds me of meeting an older, quite successful, ham. Probably broke every “rule” I ever read.

In other words. Do it. If it doesn’t successfully work, then tweak. Don’t let striving for perfection prevent one from doing.
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