I’m as green as it gets, just passed my general & extra license test but honestly know very limited about HF and the hobby.
My Problem: High SWR (Between 5 & infinity on my FT-710 internal SWR meter)
Called Yaesu technical support (talked to Harry) for help, I was told I need to address antenna’s resonance (whatever that means) issue. He said there’s nothing wrong with my FT-710 transceiver.
Current Equipment: Transceiver: Yaesu FT-710 AESS
Power Supply: Pyramid Model-PS-52KX. Also powers IC 2730, KG-XS20G & FT-710. I only transmit one radio at a time. I have another 25 Amp power supply if you recommend me to isolate the radio to a single power supply instead of the current sharing set up.
Antenna: Harvest Taurus 80M – 6M End Fed with 9:1 Unun (SO 239 for coax to transceiver, butterfly connector for wire antenna and another butterfly connector for ground); antenna wire length 64 feet; Max Power 400W; Freq 3.5Mhz; Max Voltage 40V. I also have another Harvest Taurus 40M - 6M end fed antenna with Unun still in the plastic bag (brand new) in case you want me to use it instead.
Coax: RG8X mini; 25 feet with PL259 at each end. One end connected to Unun SO239, other end connected to SO239 on transceiver.
Ground Wire: 10AWG; 25 feet to 18” ground rod (½” diameter)
Ground Rod: Mokikuba portable ground rod (bought from Amazon) 18" long, 1’2" diameter, solid steel shaft with zinc finish.
Current Setup Description: 25 feet of Coax routed from transceiver FT-710 SO239 out to Unun box SO239 mounted under roof eve (side of single story home – height of the Unun box and antenna wire approximately 8.5 feet from the ground). Wire routed under the eve from the Unun box approximately 34.5 feet in length horizontally to end of eve (to backyard) then hangs down then up (approximately 12 feet horizontally) to first tree branch. Then straight up to second tree branch approximately 17.5 feet high.
What am I doing wrong? Any ideas, help or suggestions would be extremely appreciated. I like to learn and truly open to criticisms.
Thank you for your response Bill!
I don’t know if the wire is close to metal, the eve is painted. Can’t see if there’s metal close to the wire.
Would it be better if I laid the wire on the ground (horizontally on the ground about 35 feet to wall which starts the backyard), then go up in an angle like a sloper (to about 18 feet high) to the second tree from the ground?
Let me know if that’s something better to try. If you think it is, then I’ll go do it.
I see rabbits &/or quail sometimes meandering around the neighborhood. Hopefully they don’t decide to munch on the wire if laid down on the ground.
If the eave is made of vinyl. You are probably ok. But it could be aluminum. Since you hung it up there. I assume you can check to see if it is in fact metal or vinyl.
Definitely not on the ground.
The best situation would be to run the radiating element away from the house as it exits the UNUN.
Best thing I can tell you is study up on how to properly tune the antenna without a tuner. That means adjusting the length of the wire to get the swr down. Do your homework@
Don’t lay the antenna on the ground! Antennas belong up in the air as high as you can get them and in the clear away from ground and any metal. Then you have to adjust the length of the wire to get the swr down to a usable range. I assume you took the license exam and some of this should have been covered in the material on the exam.
If the eave is made of vinyl. You are probably ok. But it could be aluminum. Since you hung it up there. I assume you can check to see if it is in fact metal or vinyl.
Definitely not on the ground.
The best situation would be to run the radiating element away from the house as it exits the UNUN.
Thank you for your response K4CKR. No. tuner used.
The FT-710 has an internal tuner. However, according to Harry (Tech Supp from Yaesu) the SWR is too high for the internal tuner. Have to fix antenna problem/issue.
I have an MFJ Versa Tuner II but I prefer not to use it because it only makes the transceiver think it’s matched to the antenna even if it really is not. The output power may not even be close to transceivers out power (100 watts). Please correct me if I’m mistaken. Like I said, I’m really new to HF (green).
When you read the manufacturer’s description, it says, “Ideal for 80-6m and when used with a good ATU, a perfect match can be obtained on all bands.” So, I think your easiest solution is an eternal tuner. Check out the MAT-TUNER MAT-Y200.
Since you live in an HOA, your front yard needs a flagpole. Look for flagpole antennas on Google.
Thank you Andreas - KL5PF
A bit on the expensive side for me though ($249.95 @ DX Engineering).
However, still better than having an FT-710 to just listen to others transmitting.
Be working on the antenna to resolve the mismatch with transceiver but will keep your suggestion in mind as an option.
Thanks again!
Hi. In general antennas should be high and away. A good dipole for 40 meters is at least 32 feet above ground level.
Lots of books on antennas from ARRL.
The age old antenna challenge; Space, elevation, clearance and $$$.
The other part is to have a good, old school, inductive roller antenna tuner. Money tends to help on these. I spent $700 and it works like a charm. I am running 1,000 watts so it is pricier.
You’re using a 9:1 transmatch? I could be wrong, it random wire uses 9:1 matches. End feds I believe use 49:1 transmatch units because the ends are several thousand ohms higher than your radio is expecting. In the neighborhood of 4000 to 5000 ohms. On top of that since it is an unbalanced antenna, you need to use a good RF choke on your feed point. Otherwise you will get nasty RF in the shack as common mode current. Your antenna needs to be as high in the air as you can possibly get it and away from metal but away from wood as well. Height above ground also changes the spot of lowest SWR reading.
Have you tested the rig with a dummy load? If you get high swr with a dummy load it’s the rig failure This happened with my first 710 . This is my reply from yeasu uk
Many thanks for your email and sorry to hear about your FT710. Sadly it may need the PA Assy unit replacing and this is £435.98 plus VAT, also an hours labour £60 plus VAT and postage. Currently our turn around is 28 working days.
Firstly I would check my aerials and feeders to ensure that they aren’t damaged. It could simply be a small crack so when the wind blows you get a poor connection and SWR flashing on and off.
Have you tried or are you using a counterpoise on your 9:1 unun? I use a 9:1 for a 41’ EFRW and it requires a counterpoise to get my desired band close to resonance. An external tuner is best, but my 7300 has been able to match my antenna on 80 40 15 with a counterpoise.
If you don’t have one, get a nano vna. This will help you adjust your counterpoise to a length/orientation that gets you the bands you want with under a 3:1 / 150 ohm feed that your 710 will have no problem matching. Good luck.
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edit: I’ve linked a better explanatory video.