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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4answers
130 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 ...
3
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3answers
102 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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3answers
61 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 ...
0
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3answers
104 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, ...
2
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0answers
71 views

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 ...
1
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1answer
80 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 ...
0
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1answer
56 views

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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1answer
190 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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1answer
80 views

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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5answers
217 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 ...
1
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1answer
46 views

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 ...
2
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1answer
334 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 ...
0
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2answers
132 views

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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4answers
704 views

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 ...
0
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1answer
59 views

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!
5
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2answers
134 views

Why does capacitive loose coupling increase selectivity?

There are mutliple 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 ...
1
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3answers
216 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. ...
2
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3answers
2k 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?
4
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1answer
388 views

Does an antenna tuner remove standing waves from a transmission line?

Does an antenna tuner remove standing waves from a transmission line ?
4
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2answers
184 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 ...
9
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2answers
909 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 ...
3
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3answers
1k views

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 ...
4
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1answer
234 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 ...
4
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3answers
2k 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 ...
2
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2answers
257 views

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 ...
3
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1answer
803 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 ...
2
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1answer
283 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 ...
1
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2answers
277 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 ...
2
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2answers
592 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 ...
12
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4answers
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 ...
3
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1answer
1k views

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 ...
4
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3answers
5k 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, ...
8
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4answers
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 ...
2
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3answers
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 ...
9
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2answers
2k views

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 ...
3
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1answer
933 views

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? (...
2
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5answers
3k views

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 ...
1
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2answers
396 views

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 ...
2
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3answers
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 ...
2
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2answers
532 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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1answer
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 ...
3
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0answers
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 ...
4
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2answers
1k 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 ...
0
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1answer
233 views

Understanding needed with LDG AT-100Pro

I bought an LDG AT-100Pro via CheapHam. Supported equipment: Yaesu FTDX3000D, ZS6BKW multiband antenna. I bought this as an improvement over the FTDX's internal tuner. The LDG does a great job ...
8
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1answer
711 views

Antenna tuning while receiving

I've built AA5TB's antenna coupler for a 5W 20m transceiver. Tuning was kind of difficult because my transceiver has buttons for sending a dot and a dash, but no tuning mode, so I couldn't have the ...
5
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2answers
1k views

Adapting an antenna coupler

I've built AA5TB's antenna coupler: I left out C2 because I didn't understand why I would need it - why would I? It works fine without. Unfortunately, when I started tuning for a 5W 20m transceiver, ...
9
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2answers
2k views

Why is the risk of damage to a transmitter due to a mismatched antenna at lower frequencies greater?

A quick follow-up to this answer ... If the impedance mismatch is large, you risk damaging your radio, particularly on the lower frequencies ... I'm sorry to be so dense, but uh why is the risk ...
5
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1answer
674 views

Do vacuum variable capacitors have higher Q than air variable capacitors?

Do vacuum variable capacitors have higher Q than air variable capacitors? They are not commonly seen in tuners or crystal sets. But they are mentioned as superior to air variables for resonating ...
2
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1answer
641 views

What range of mismatch can the internal tuner on the TS-480SAT accommodate?

A fellow ham recently acquired a TS-480SAT. His working condition is complemented by an inverted-vee for the 20m band around 10m above ground; solid 59+ reports. Trying to tune the same antenna on ...
10
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3answers
884 views

What is the best practice when tuning an antenna on air?

I have a magnetic loop antenna that takes a long time to tune and of course, while tuning it, I need to be transmitting. What is the best procedure for tuning on air? I understand I need to check ...