Questions tagged [antenna-tuner]

Questions relating to the setup and use of antenna tuners, the virtues and shortcomings of various types of tuners, etc.

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Is it worse to use an antenna tuner on an already-loaded short monopole?

If I had a good transmatch and wanted to use a spare CB antenna on the amateur HF bands, would I be better off bypassing its tuning coil completely? One ham pastime is using an antenna tuner to match ...
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1 vote
0 answers
71 views

Help understanding Kenwood AT-230 tuner topology

Can you help me understand what the topology of my Kenwood antenna tuner is trying to do and what it might be compared to? Below is the schematic of my Kenwood AT-230 antenna tuner, and below that ...
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3 votes
1 answer
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Is there a name for this specific variation of L-match tuner (somewhere between L-match and Π-match) and what would be its advantages over L-match?

So I've been looking at the internals of the Icom AT-141 end-fed antenna tuner which I have, and I've noticed that it has some sort of pre-tuning LC stage before its traditional L-tuner network. ...
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5 votes
5 answers
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Does an antenna pick up signals of all frequencies or only its resonant frequency?

I heard that an antenna picks up signals of all frequencies, and then these signals are filtered by a circuit using an inductor and capacitor, and that this is how a radio is tuned. However, I also ...
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2 votes
1 answer
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Reasons for an antenna tuner at the transmitter other than transmitter protection?

An antenna tuner colocated with the transmitter may be required to prevent transmitting into an SWR higher than the allowed specification for the transmitter, or if the transmitter might overheat or &...
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4 votes
5 answers
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Antenna tuner at the transceiver output confusion

I am a bit confused. Let's take a HF transceiver for example. My understanding is that the output impedance of the transmitter is 50 ohms. The impedance of the coaxial cable feedline is 50 ohms, and ...
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5 votes
2 answers
134 views

Is tuning at all useful for an antenna that is already resonant?

Say you have a resonant antenna that also has a tuner. Does this help at all? Can your antenna be "fine tuned" ?
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7 votes
4 answers
212 views

Tuner at antenna side versus transmitter?

I figure the transmitter has a 50-ohm pure resistive output and that the transmission line is 50-ohm as well. I think it's usually the antenna itself that actually needs to be tuned, yet it sounds ...
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3 votes
3 answers
264 views

SWR of 1.5 -- use internal antenna tuner or not?

My IC-7300 has an internal antenna tuner that can handle a SWR of up to 3:1. The other day I noticed that a frequency I was transmitting on (the 40m FT8 frequency FWIW) has an SWR of 1.5 (was my first ...
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1 vote
3 answers
120 views

SWR erratic based on time of day

I have an odd issue - SWR swings wildly, like a loose connection (there are no loose connections), on 17 and 15 M, only mid-afternoon local. I have made contacts as far as Japan (from central NC) at ...
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3 answers
141 views

What happens to the signal level if the antenna has high SWR?

I'm currently reading "Reflections: Transmission Lines and Antennas" by M. Walter Maxwell, W2DU. This book explains well why the energy is not lost because of high SWR during transmitting, ...
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2 votes
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MFJ-939 not working with FT-450 - TUNE blinking

I have recently bought second hand MFJ-939Y for FT-450/950. I have Yaesu FT-450 (plain, without D or AT). Since the tuner did not come with a cable, I have built my own. (I am 33yo IT engineer with ...
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1 vote
1 answer
101 views

Antenna Tuner Range

I have a Kenwood TS-480S and a Kenwood TS-870S both with built in antenna tuners. On the TS-870S I have a ZS6BKW multiband antenna and on the TS-480S I have a vertical whip with two counterpoise lines ...
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1 answer
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Estimating SWR based on multiples of resonant length

I am planning to buy a Xiegu G90. It has an internal tuner that can tune up to SWR 5:1. Does anyone know if I have a resonant antenna on 40m, what I will have for a SWR on 80m?
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1 vote
1 answer
289 views

What may be damaged when using an internal antenna tuner on SWR above 3?

The Kenwood TS-570S comes with a warning against using the internal antenna tuner for antennas with SWR > 3, even though it may tune (e.g. at SWR 3.5 or 4). It says the transceiver or antenna may ...
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1 vote
1 answer
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Need way to indicate when rotary inductor reached its limit switches on a remote homebrew motorized hf tuner

I have a homebrew motorized hf tuner which is controlled by coupling dc from the shack through two BiasTs - one topside, the other in the shack. As I reverse polarity to adjust tuner, will two LEDs, ...
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5 votes
5 answers
360 views

How can a tuner pick up a specific frequency?

The point I'm confused about is the antenna. Depending on the environment, there are tons of different frequencies passing through you (FM, AM, 4G, SAT, etc). The electrons in the wire will move as ...
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1 vote
1 answer
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Bidirectional motor control using MFJ-4116 with RCS-4

I have the RCS-4 with two MFJ-4116. Prior to installing my motorized HF antenna system topside, I bench-tested the core of the assembly in my shack. The MFJ-4116 near my transceiver was injected with ...
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2 votes
1 answer
458 views

Should I bother with a doublet if I can't go straight to the tuner with open wire?

I have two trees about 135 feet apart and about 55 to 65 feet tall. I have been trying to determine which kind of wire antenna to put up there. Initially I was considering either a fan dipole or ...
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Built-in ATU vs Remote?

I have two antennas in my station: a 10-15-20M yagi, and a loaded 40M vertical. With the ATU built into my Kenwood TS-450S I can operate 80, 60 a and 30M with the 40M vertical too. Though, in 80M I ...
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1 vote
4 answers
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Can I splice a random wire antenna?

I have an Icom AH-4 with a random wire antenna. I have a fence around my property that is 60 feet long by 70 feet wide. The outdoor tuner is placed at the begining of the 60 foot section which leads ...
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0 votes
1 answer
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Problem with mAT30 ATU and FT-450D transceiver

Does this tuner work with this transceiver? Would appreciate response as I cannot get it to work!
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6 votes
2 answers
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Why does capacitive loose coupling increase selectivity?

There are multiple ways to couple antennas. It is said that an antenna is capacitive loose coupled if a small capacitor is used between the antenna and the parallel resonant circuit (like C2 in the ...
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1 vote
3 answers
230 views

Do I always need a tuner at both ends of the transmission line or is that only for certain types of antennas/circumstances?

Last night was my first night on the air as a General licensee and at HF. I've got an IC-7300 with the built-in antenna tuner. I'm pretty sure I understand how to operate the radio, for the most part. ...
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2 votes
3 answers
3k views

Ideal Doublet Size 160-10 Meters

Is there considered an ideal / optimum length for a doublet for use on 160-10 meters when fed with open-wire feedline and a balanced tuner in the shack?
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4 votes
1 answer
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Does an antenna tuner remove standing waves from a transmission line?

Does an antenna tuner remove standing waves from a transmission line ?
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4 votes
2 answers
238 views

Pi Matching circut for tube PA - what values?

I am working on my 80m and 40m CW transmitter and ran into a problem: I need to match the high impedance of PL504 to 50ohm coax, a Pi match seems to be the best, but I don't know how to calculate ...
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9 votes
2 answers
1k views

What types of materials increase the inductance of a coil when inserted inside it?

I'm asking this because of the comments in this answer, that imply that steel (mostly iron) has similar characteristics to ferrite. Specifically, it is implied that inserting solid steel into a ...
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3 votes
3 answers
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Yaesu FT-891: power drops to 50% when TNR is ON and SWR is 1.5:1

I noticed a weird behavior of my Yaesu FT-891 transceiver. I'm using it with an external autotuner mAT-30 (120W SSB/CW, 30W PSK31), which is compatible with Yaesu FC-50. When I connect a 100W 50 Ohm ...
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4 votes
1 answer
261 views

What dielectric strength is required for a variable capacitors in a 100W T-network antenna tuner?

I would like to build a 100W T-network antenna tuner: I have a 12-pole wafer switch, 12.5 meters of enameled copper wire (d=1.5mm) and a pair of 12-365pF variable capacitors rated 200V DC (dielectric ...
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4 votes
3 answers
3k views

Do I need an 9:1 UNUN for a half-wave end fed?

I was using a 10-ish meter wire as my HF rx antenna. That's all I can install in my QTH. However I realised that my ~10 m wire can be turned into an end fed dipole for 20 meter band. But there is a ...
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2 votes
2 answers
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Can anyone tell me how to make a 35 m long wire antenna work on 80, 40, 20, 15 and 10 metres?

I have one straight horizontal wire antenna 35 meters (114.83 feet) long. I want to make it work the best on average for the 80, 40, 20 ,15 and 10 meter amateur bands. Can anyone tell me the best ...
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  • 3,393
3 votes
1 answer
953 views

Benefit to remote antenna tuner for end-fed non-resonant antenna?

Does addition of a remote feed-point antenna tuner affect the use of the coax braid as a radiator? If it no longer "radiates" in such a setup, what does? Is a shack or remote tuner better for ...
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2 votes
1 answer
307 views

Does an LDG YT-100 automatically trigger a tuning cycle if the SWR is high?

I have a YT-100 connected to my FT-857d in my remote-by-default shack in the attic (i.e. I operate it over a VNC connection from elsewhere in my house). Whenever I change band I have to go up to the ...
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1 vote
2 answers
297 views

Rotary Inductor Replacement

I thought it was time to build a balanced-balanced antenna tuner so I mechanically ganged two B&W 3852 rotary inductors to make a balanced L network. It appears that the 16 uH inductors I used ...
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2 votes
2 answers
697 views

Using one of two antenna tuners connected in series

I have: A Kenwood TS-590SG. 2 antennas up, a tri-band beam and a fan dipole. I run both antennas to a MFJ-998 auto tuner. I also have a MFJ versa tuner IV. The auto tuner works good for 80-10 meters ...
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12 votes
4 answers
3k views

What is an antenna tuner? Why bother with resonant antennas in the first place?

There are a lot of antenna tuners on the market that have various capabilities in terms of how they can allow random radiators to work with our transceivers. What exactly do they do? My ...
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4 votes
1 answer
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Is ladder line necessary when using a non-resonant dipole through a tuner?

I've heard if I have a dipole of some arbitrary length, or a random wire, the SWR can be very bad. An antenna tuner can present a decent match to the transmitter, but the SWR on the feedline will be ...
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4 votes
3 answers
6k views

Antenna tuner design

In a related question about a broadband antenna for SDR it was suggested me to build or buy an antenna tuner. Since maybe it was not clear to everybody, I'm designing an antenna tuner for reception, ...
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8 votes
4 answers
1k views

Two Antenna Tuners in Series

My radio has an internal antenna tuner that can be activated to rapidly tune for the frequency in use. My antenna has a disgusting SWR for the band I want to use (as measured with an AA-54 antenna ...
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2 votes
3 answers
2k views

How do I set up my radio for an antenna tuner?

I recently acquired an MFJ Versa Tuner II model MFJ-949D as well as a Kenwood TS-430S radio. The instructions for the tuner state (in part): For optimum operation of the MFJ-949D, the transmitter ...
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9 votes
2 answers
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What is the actual loss in a feed line with high SWR?

It is well-known that it is unwise to have standing waves on the feed line between one's antenna and one's transmitter, unless it is a very low-loss type (e.g. ladder line), because the transmitted ...
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3 votes
1 answer
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Using an HF antenna for VHF scanning

Are there any disadvantages (or advantages) to using a long-wire HF antenna for wide-band VHF reception? Or would feedline losses make that useless compared to a ground level ducky or short whip? (...
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2 votes
5 answers
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Balun and tuner configuration for multiband dipole

I'm putting up a multiband dipole in some tall trees. (Perhaps it's more correct to call it a "dipole-doublet"). The situation I'm imagining looks like this: The legs of the antenna are each 100 ...
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1 vote
2 answers
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Tuning an antenna with cold weather

I have a 20m long dipole that starts at 2m above the ground and ends at perhaps 20m above the ground. It was -10 °C here tonight (that's +14 °F), currently around zero (32 °F) and my antenna is out of ...
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2 votes
3 answers
3k views

Will an Internal Antenna Tuner work with an external HF amplifier?

I am a new General and don't quite understand how Antenna Tuners work other than changing the impedance ratio between the radio and the antenna. So my question is - Do I need to buy a new tuner if ...
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2 votes
2 answers
591 views

Adapting an antenna tuner for use with a panel meter instead of an LED

I'm building NorCal's / W6JJZ's BLT tuner (pdf) for use on 40m/20m with a 5W transmitter. I would like to remove the LED and use a small panel meter instead. I don't have a 1N34A at hand, but I do ...
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1 vote
1 answer
1k views

Do a toroid's specs matter much in an antenna matching transformer?

I'm getting started with my first (very basic) HF rig and for convenience and the experience I'd like to try an End Fed Half Wave antenna. Typical designs for a "matchbox" in this case include ...
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3 votes
0 answers
1k views

TS-590 Antenna Tuner Protocol

I'm looking for the protocol used by Kenwood's TS-590S antenna tuner port. I've worked as far as I can with Kenwood's tech support. They know what the pins are labeled, but don't have any information ...
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4 votes
2 answers
2k views

Where does one find high-voltage variable capacitors and inductors for RF? [closed]

I'm looking to start building various antenna tuning circuits, but I'm limited by my parts inventory. I have pots and mag wire for winding inductors and a nice spectrum of fixed-value capacitors, but ...
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