Antenna Tuners

[A71AN]

I have seen much type of antenna tuners in the market plus those rigs with their built in tuners, how much effective those tuners are is matter of suspensions!

I came across many people saying that if the antenna itself not been toned to the frequency the synchronizing ratio between the rig and the antenna is of no effect, you go tuning and tuning to drop the swr but you loose all of the gain.

When the antenna is tuned, you get the optimum gain out of it.

I do use 2 MFJ 3KW tuners and going to buy another 2 PALSTAR tuners, one for my radio room and another for my portable need.

I do not know how much gain and effect I would get out of these tuners; I will appreciate your opinion about the tuners need.


Thank you and 73 to all

[WB2WIK]

Antenna performance is whatever it is, based on the design and installation. Tuners can't add or subtract any gain from them.

All a tuner does is try to transform the antenna system impedance to 50 Ohms, because the design point for all our transmitters (as well as our power meters and SWR bridges) is 50 Ohms. Whether the tuner is "inboard" (built-in, automatic) or "outboard" (outside the transmitter, either automatic or manual), they all do exactly the same thing.

Internal tuners can have more loss (this isn't antenna loss, it's just "tuner" loss) because the components and conductors are small and have more resistance than they should. Some outboard (external) tuners, especially the very BIG ones (usually rated 1500W or more), have less loss because the resistance in the inductors is much smaller. It's just a matter of "size."

Small external tuners that are only rated 100-150W have just as much loss as the internal ones do.

WB2WIK/6

[G0GQK]

A dipole antenna, whether it be brought into resonance by cutting the length of the wire to bring it into resonance at a chosen frequency, or if it is brought into resonance by use of an ATU, will radiate exactly the same energy at that frequency.

The ATU's which are now part of the internal equpment of many tranceivers should properly be called trimmers. They were intended to bring into resonance antenna's which are already almost resonant. Many are unaware that by using the internal ATU they are perhaps losing as much as 20% of their RF output. As many QRP stations are able to get around the world on 5 watts the loss of 20 watts on an average transmission won't matter much.

G0GQK

[KC0BUF]

The idea being, of course, that when your rig sees an incorrect impedance, it may drop the power output. You're going to lose power no matter what you do, but if your rig is putting out 100 watts instead of 30, it's going to make a fairly sizable difference in the transmitted signal. THAT'S what an antenna tuner unit does. It can't make your antenna more efficient, but it can help the situation.

[WB2WIK]

A dipole antenna, whether it be brought into resonance by cutting the length of the wire to bring it into resonance at a chosen frequency, or if it is brought into resonance by use of an ATU, will radiate exactly the same energy at that frequency.

The ATU's which are now part of the internal equpment of many tranceivers should properly be called trimmers. They were intended to bring into resonance antenna's which are already almost resonant. Many are unaware that by using the internal ATU they are perhaps losing as much as 20% of their RF output. As many QRP stations are able to get around the world on 5 watts the loss of 20 watts on an average transmission won't matter much.

G0GQK

::I'd say, "yes and no." True, an internal ATU can dissipate quite a bit of power under some conditions, but then so can an external antenna tuner. Depends what it's trying to match and how large the inductors are.

As for tuning range, the internal ATU in my Jupiter has a matching range of 5 to 500 Ohms (VSWR 10:1) and typically finds a match in less than three seconds.

Matching loads closest to 50 Ohms it has almost zero insertion loss (measured this); when it introduces most loss is matching loads that are much <50 Ohms, and at the low end of that scale, the loss can be more than 20%. On 160m, matching a 10 Ohm load, it loses almost 40%. Much better than not being able to transmit, which would be the other option.

A big, fat external tuner with huge conductors for the coils would lose less but also occupy a lot more space.

Internal ATUs are pretty good nowadays.

WB2WIK/6

[KI4NGN]

A dipole antenna, whether it be brought into resonance by cutting the length of the wire to bring it into resonance at a chosen frequency, or if it is brought into resonance by use of an ATU, will radiate exactly the same energy at that frequency.

The ATU's which are now part of the internal equpment of many tranceivers should properly be called trimmers. They were intended to bring into resonance antenna's which are already almost resonant. Many are unaware that by using the internal ATU they are perhaps losing as much as 20% of their RF output. As many QRP stations are able to get around the world on 5 watts the loss of 20 watts on an average transmission won't matter much.

G0GQK

Sorry, but an antenna tuner does nothing to adjust an antenna: it has no impact on the antenna's resonance. The antenna is what it is.

A tuner's sole purpose is to match the load impedance to the transmitter's requirements, normally 50 ohms.

One of the main limiting factors for internal tuners, as Steve has mentioned, is the size of the components, which relates directly to their maximum voltage handling. The mismatch limit is determined by the high voltages that may be present, which increase with the increasing mismatch between the actual load and the transmitter's 50 ohm load requirement.

Mike

[N9VBI]

I pretty much echo comments by WB2WIK. I also have the MFJ external tuner, think it does a much better job the internal one the Yaesu provides. Hope that helps.
73's -- Burt - N9VBI

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