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Reviews For: JK Antennas JK403

Category: Antennas: HF: Yagi, Quad, Rotary dipole, LPDA

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Review Summary For : JK Antennas JK403
Reviews: 3MSRP: 2,595.00
Description:
The JK403 is a great performer antenna on a 30ft boom for 40m. This antenna has excellent F/R and gain while maintaining a decent SWR bandwidth. The antenna is made with our high quality, heavy duty materials and hardware. The element construction does not need trussing unless you live in extreme snow/ice conditions.

We can also provide you with custom settings to suit your operating preference such as peaking your gain and F/B in the CW portion or the Phone portion of the band.
Product is in production
More Info: http://jkantennas.com/jk403.html
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0035
W5QG Rating: 2022-02-13
Well built, meets specs Time Owned: 0 to 3 months.
Have had my JK403 up at 200' for ~ 2 mos. now and as others have said, hardware and build quality are nonpareil. Ken is likely to call before delivery and is available for questions afterwards (never experienced that before!). Individual packaging/labeling of parts w/ a few extra thrown in is a nice touch. 2:1 bandwidth as advertised, great performance with a noticeable drop off in signal strength for just 20-30 deg. rotation. Mine survived an ice storm w/ no damage, although of course, SWR is off when wet.
A few observations: (1) for TIC ring rotator, may have to move the "attach point" a bit, and "window" between cradle and active element/balun is close, and 2" boom may not fit tightly enough to avoid rotation of boom w/ ice, so would need to pin boom or obtain special truss hardware from Ken, (2) as w/ other yagis, dressing of coax seems to be critical to tuning, as mine didn't tune so well w/ coax dropping down directly from balun, but nominal when dressed horizontally along boom several feet.
I've had five other antennas up on this tower (Force 12 40m 4 el, 4 el Lightning Bolt quad, Force 12 80m/40m Magnum 2/2, SteppIR 4 el, and Cubex 4 el quad), all eventually succumbing to wind or ice, but I expect the JK403 to survive as long as I do! I've got a 206 coming and planning on a Quattro!
NW3Y Rating: 2018-07-26
Good choice Time Owned: 0 to 3 months.
I replaced a 2 element 40 meter beam with this JK-403 only one month ago, but I have been impressed with it. I had good performance on 40 cw in the recent IARU/WRTC contest with lower power settings. Testing showed a predicted improvement as I compared both beams side by side. This beam is beefy and very well made. The construction is very basic and the directions, supported with photos, made the build about as easy as you can get. Every bag of parts is extremely well labeled and even has an extra piece or two for those of us who tend to loose one along the way. I like the boom-to-elements "clamps" which are unique and very well designed. At 125 lbs and 12.6 sq ft, I put this beam on its own tower at 80' which is where HFTA analysis suggested. The settings in the manual for cw were good as published, but I asked Ken for some field refinements and he was right on the money with the minor adjustments based on our readings as we were attaching it to the mast. This antenna has as SWR of 1.12 at 7.035. Nice job Ken!
N8CC Rating: 2015-05-01
Excellent Value! Time Owned: 6 to 12 months.
I have had my JK403 for a full DX Season now, and a review is in order.

It has been a Joy! The performance of the JK403 has been all I could hope for.

First things first. The mechanical design of the JK403 is what I would call 'elegant simplicity'. While the instructions are very well done, I believe one could assemble the antenna correctly without them. Ken's eye for detail is such that I found myself saying 'wow, this guy is fussier than I am!' All hardware is grouped and labeled in a sensible manner, which makes a project of this size much easier. High quality stainless hardware is the order of the day, with machined boom/element and boom/mast clamps for a perfect fit. Ken will customize the clamps to your mast, if necessary.

Installation was uneventful, with one tower man and one ground man. I found that the antenna doesn't 'feel' as big and heavy as it is, because it is so well balanced. I was able to move it into position with little effort, and final mounting was very quick due to the excellent design. At no time did I feel like I needed a 'third hand' as so often happens with this sort of project.

Ken was kind enough to email me a printout of the SWR/FB curves for my new antenna, to help pick a target center frequency (yes, Ken will give you custom dimensions for your needs). In the end, his computer model was within 8-10 kHz of what I measured at the antenna terminals. Impressive!

In operation, the JK403 has been very satisfying. I have always been of the 'Life is too short for QRP' mindset. In spite of that, I must confess to turning the power all the way down to a couple of watts from time to time, just to see if I can find someone who CAN'T hear me. It just doesn't seem to happen. This is a top notch performer, and will open up a whole new world for you on 40 meters.

One thing that struck me the other day, is how the JK403 acts in a strong wind. I was watching the tower, and comparing it to the HyGain 2 element that is halfway up the same tower. The JK403 was just kind of gently flexing in the breeze, while the HyGain seemed to be trying to go in all directions at once. I'm sure all this makes perfect sense to an engineer, but I was amazed at how hard the lighter antenna seemed to be working in the wind, in spite of catching less of it. Seeing both react to wind loading at the same time, the difference is striking. Also, the balance is such that the rotor doesn't seem to be working very hard at all. Even when the JK403 is loaded with ice, it turns very easily.

As far as customer service goes, JK Antennas is as good as they come. In sharp contrast to many companies, Ken actually WANTS to talk to the customer. During construction/installation, he would drop me an email or phone call regularly, just to make sure everything was going ok. When was the last time you had THAT happen? Wow!

I am not a rich man, and the JK403 is not a trivial investment for me. This is the classic 'price vs. value' decision. I have never regretted my choice, and I sleep better knowing that the JK403 will take whatever Mother Nature throws at it.

Jeff - N8CC