Manager - NA4M
Manager Notes

Reviews For: Stockcorner JC-4 automatic antenna tuner 1KW

Category: Antenna Tuners/Matching Networks

eMail Subscription

Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted.
Review Summary For : Stockcorner JC-4 automatic antenna tuner 1KW
Reviews: 26MSRP: 1050 Euros
Remote antenna tuner rated for 1KW pep. Two antennas. High
quality parts and high performance coupler.
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
G3RCE Rating: 2023-05-24
Excellent amu+support Time Owned: more than 12 months.
Had a minor problem which was very quickly sorted by Casper at Stockcorner, no charge just postage to and from the Netherlands, amazing service. thankyou Casper.
After over 2 years using the JC4S I can thoroughly recommend this unit.
I press the button on the control box, then apply 10watts (always less than 20 watts) carrier and wait for the red led to go out. Hey presto you’re on air.
My first JC4S for the first year was unprotected from the weather, looked inside, no sign of any damp etc. however I do use a protective box now.
73 Rob G3RCE
HB9CQK Rating: 2022-06-25
Outstanding Service! Time Owned: more than 12 months.
Our Stockcorner JC-4s antenna tuner had to be replaced in early spring 2022, because accumulated condensation inside the ATU housing caused malfunction. Fortunately, we had a spare ATU. We assume that the high amount of condensation was caused by the extreme weather conditions on Mount Rigi. The temperature on the surface of the ATU my vary by 40(!) degrees centigrade on a single winter day. E.g., -15 at night to +25 during daytime. The formation of condensation water inside the tuner must be correspondingly high. The JC-4s had no condensation venting device (up to now). We sent the damaged ATU to Casper from Stockcorner. He managed to get it working again, but not only that: He installed an all-new housing with a new control cable connector and a condensation venting device at the bottom of the housing. Because I told Casper that I do not fancy soldering a new plug to the control cable at 15m above ground while hanging on two ropes he made an adapter cable for us, so we could use the control cable as is. On top of that he also sent us modification kits for our JC-4s tuners that we use at home as well as for the Mount Rigi spare ATU. All this at VERY reasonable cost. I must say I was speechless at first (that is VERY unusual). This level of customer orientation and service is extraordinary! Needless to write that the repaired tuner works flawlessly. Great job Casper and thank you VERY, VERY much! Mount Rigi DX-Station 1660m ASL, Central Switzerland, HB9CQK & HB9RYZ
K1LH Rating: 2021-12-22
Excellent Time Owned: 0 to 3 months.
I've had my JC-4s for a couple weeks.

I'm using it with a 130 ft doublet at 55 ft fed with 600 ohm line via a 1:1 ATU balun from Balun Designs. I also have a stack of 8 Mix 31 snap-ons on the control and coax cables. Tuner is directly below the antenna 10 ft above ground under 2nd level deck where its protected from the weather.

Tuner gets 1:1 SWR on most bands, and 1.2:1 or better on the others. All ten between 160m and 10m. Some further adjusting of the 600 ohm line length I could probably get it better. I did my feeder length adjustment with an analyzer so I can be sure the JC-4s is not being presented with any wild impedances low or high.

I have it interfaced to my Icom 7300 tuner/ATU port, with the A/B switch in a little control box I built. Tuning via Tuner button or PTT press, or digi mode app Tune command. The Icom will initiate a tuning command after band change, or moving around in the same band when needed. Retunes once learned are near instant and seamless.

I did find with my JC-4s interfaced to the IC-7300 that 10W carrier was not quite enough on 17m and higher. Tune times sometimes took up-to a minute or more, but were instantly recalled once learned. Casper was very helpful and responsive to the issue, and we verified using the supplied manual tuner interface and 20W carrier to tune, issue went away. The TUNE carrier power level can be adjusted in the IC-7300 per the service manual. I have bumped the tune power in mine to 20W to resolve this issue with my setup.

I plan to build a remote switching network controlled via the A/B switch and feed the doublet as T antenna by linking the two feeder legs together, bypass the balun and drive it against ground for an alternative set of patterns on 160 - 30m.

My control cable is made using high quality shielded CAT7 (CAT5 or 6 also fine, CAT7 is just what I happened to get). I join the pairs to make 4 wire cable, its 130 ft or 36 meters long, works fine.

This unit is essentially the big brother to the Icom AH-4 I also have, it is a great 100W tuner for Icom rigs I have used to feed balanced antennas.

JC-4s is the quality and price we should expect.
JW4PUA Rating: 2021-04-28
Perfect, just works Time Owned: 6 to 12 months.
I am using the tuner with an inverted L wire antenna, 15 meter up and 20 sloping to the side. I have 72 radials. I bought it mainly for the low bands, but it works really good on all HF bands. I use it with an amplifier and using the control box. Tunes fast. It has memory, but you can easily override the memory if the conditions changes. And its often so here. Snow and rain changes the SWR, just tune again.
Good protection system if you tune with high power (when you forget, and tune with the amp on).
I usually run SSB with 1kW. But if the conditions ist the best I go digital. You cant go full power on digital, but I can run FT8 continuously with 330Watt.
It works better than my Butternut 40/80. I can use the whole band.
Easy to set up. Works well with simle antenna setup. Give me all band and low SWR on the whole band. Give me the contacts I want.
Highly recommended.

Sander JW4PUA
ON5MF Rating: 2019-12-25
Very happy Time Owned: more than 12 months.
I use this tuner mainly for the bands 30m and lower. My antenna is a 'random' length inverted L, the vertical part is about 15m and the horizontal part is about 70m long.
Around my tower there are 60 radials, some 5cm beneath the soil.
The tuner tunes all HF bands 10m - 160m flawlessly!
K4JJW Rating: 2019-07-11
Totally satisfied Time Owned: 6 to 12 months.
You can purchase this tuner with confidence. I've been using auto-tuners for about 15 years and the JC-4 is very versatile and reliable. I use it on a 162' inverted L and it tunes all bands with ease and with a very low SWR. I'm in "hurricane alley" so I installed a simple weather shield above the JC-4. Casper's response time was excellent. Top quality components and construction.
PC3T Rating: 2019-06-08
Amazing ATU Time Owned: more than 12 months.
I've been using this ATU for 1,5 year inline with my 80m Inverted L. I can tune on 160m easily with around 20m long wire and a bunch of different sizes radials. Also the support from Casper is superb he never let me down when I raised some questions. I use the ATU also for all other bands that I do not have antenna like 60,30,17,12m bands and all tuned in 2-3sec. The price is a bit high but you get what your paid for, pour quality in all aspects.
MM1APS Rating: 2018-09-07
Simplifies things a lot! Time Owned: more than 12 months.
I use the JC4s for my holiday vertical - a 12m wire on a telescopic mast with eight radials on the beach - and for long-wires.
I intend to install the guts of the thing in a Peli-case with military connectors for ultimate weatherproofing - the 4-pin control socket and SO239 are quite short and not always easy to get the self-amalgamating tape round - otherwise it seems pretty much perfect, even allowing the use of doublets with balanced feeders.
W8IXX Rating: 2017-11-22
Initial evaluation of JC-4S remote tuner Time Owned: 0 to 3 months.
I was about to purchase a new JC-4S when I discovered a used unit on Ebay two weeks ago. I am lucky to have found it!

I use the JC-4S to tune two antennas: (1) a “Super Slinky” inverted-L for the 160 meter band and (2) a 12m (38') sloper for 40 – 10 meters. The inverted-L is connected to Channel A and the sloper to Channel B. For stealth the antennas are located in a wooded area about 200' from the shack, and the tuner is fed with a long run of RG-8X. The two antennas share a counterpoise consisting of nine wires placed in a somewhat random radial pattern. The tuner is placed at the connection point of counterpoise wires. The proximity of the antenna to property boundaries makes it impossible to have perfectly distributed radials.

The Super Slinky antenna for 160 meters allows operation on Top Band in a small footprint. (The antenna was a winner in the 2017 ARRL Antenna Design Contest.) NEC simulations show that the SS antenna is a good radiator on all HF bands, but its impedance varies widely from band to band. With the JC-4S it is possible to load up the Super Slinky on all bands from 160m through 10m and the sloper on 40m through 10m. The JC-4S drops the VSWR on the long coax line to under 1.3:1. This reduces losses due to high VSWR, which become significant on the higher HF bands. The low VSWR also allows use of a solid-state linear amplifier without excessive reflected power that would trip the amp's protection circuits. I can now run the amp at full power (500 W PEP on SSB) and 300 W on CW and digital modes on all bands.

Tuning and band changing with the JC-4S are very easy and fast using the provided little box. I tune using a 20 watt carrier signal. I plan to use my Kenwood's ATU button to tune the JC-4S once I get the connector that fits the Kenwood ATU control port. The only downside in my installation is the need for a long control cable. I use 200' of 8-conductor UTP cable purchased at Home Depot. To reduce ohmic loss I make four pairs of conductors. This has worked well. A good project would be to build a Zigbee-based remote control.

Quality of construction of the JC-4S is outstanding, and Stockcorner's user support is very good. Casper responds very quickly to email enquiries and is generous with his time. I can't imagine getting better support.

The JC-4S has vastly improved the performance of my station. The ability quickly to change bands, switch antennas (which allows the operator to choose the better antenna for a particular QSO), and run my amp at full power has resulted in improved operation on all HF bands and many more QSOs than before. I give the JC-4S my highest recommendation.

HA5X Rating: 2017-08-21
First impressions Time Owned: 0 to 3 months.
This is going to be about my - very positive - first impressions. I hoped to write a more thorough review after some more experimentation, but unfortunately I have not had as much time to play with it as I had hoped. I might write a follow up later.

As at home I only have a 3x1 m balcony as an antenna farm (and I promised my XYL half of it will not have any antenna of that "huge" plot) I have to resort to temporary, low footprint antennas. That usually means a vertical fishing rod with one inadequate radial, or another fishing rod holding a radial horizontally over the neighbour's garden. Of course nothing can stay, I have to remove all after the weekend contest...

Given these limitations, I have had to make severe concessions and found that in my case non-resonant antennas are the easiest to use: push out some wire along the fishing rod, tune it to impedance with some tuner and enjoy. No time to fine tune something resonant just for the few minutes there antenna is there for... But, such antennas are very lossy and I sometimes compensate for this loss by using 300W, that makes me sound just a bit weaker than a 100W station with some proper antenna :)

After having used indoor desktop tuners and a 9:1 UNUN for a decade anda half, I finally decided to try a remote tuner for two main reasons. First to reduce the loss of my coax and also to make tuning a bit more comfortable than having to do it manually. While browsing reviews for some commercial tuners, I accidentally ran into this very JC-4s review page on eham. Nobody gave this tuner less than 5. Woww, interesting. While most available remote tuners are 100W only, this one can easily handle more. Woww. So I navigated to the stockcorner website and read the available info there. I sent an email to Casper, and he responded literally within minutes. Woww. All questions answered. I paid using PayPal and the box arrived to the other corner of Europe within 4 working days. Woww.

The tuner seems well built from the outside (I have not opened the box yet.) It is a bit bigger than I had expected (but actually it is still smaller than another tuner I was looking at), so it might not be travelling in my suitcase, but I will buy the smaller JC-3s for travel, but who knows :) As an eager boy I just wanted to try it ASAP. Unfortunately there is no control cable in the box, you have to prepare some wire yourself to hook it up. UTP is explicitly not recommended for this purpose, but as I happened to have quite a few meters of UTP on a drum it was obvious that I cut a 15m or so long piece and soldered up 2x4 wires to the supplied plug on one end and the control box on the other. Honestly, a few minutes after my first experiments I decided to add some connector between the control box and the control wire, as if you want to use it like me (not connect it once and leave it there) having the control box soldered to the whole length of the cable will make it quite difficult to lead the wire in the room, it is way easier just to lead the cable itself an then connect the tiny control box once the cable end has reached the radio desk. Not having some connector on the back of the control box is actually the only one negative point of design I have found so far. But anyone - even I - can DIY something in a few minutes, so not a big deal.

Anyway, I placed the tuner under the fishing rod, pushed out some 7 meters of wire with some random coil, and an absolutely random length of wire on a 5m fishing rod as counterpoise and powered up the thing. There you have to be very careful: you either have to run the tuner from the power supply of the radio itself, or connect the ground of the radio with that of the other power supply, otherwise it will not work. Although it is clearly stated in the manual, I just forgot about it first and was scratching my head for a few minutes thinking the tuner did not work. But it actually does, it was the operator who was lame :)

Tuning goes very fast indeed, within seconds the "antenna" matched on all bands from 160m to 10m. I heard a few stations on 80 and 40m, and whomever I heard also replied when I called them. The tuner memorizes tuning at different points within a band, so it is very convenient, however, you have to re-tune it after changing the band. But as it takes only a few seconds to tune, it should not be a problem.

I had some RF feedback problems inside the shack at first, but by adding a common mode choke at the tuner-end of the coax it is fine now, even with 300W. Whatever wire I just connect up, the tuner will match it just fine. The only band where I have had some difficulty was 10m, I think some of my wires are a bit too long electrically for that band. Fortunately, the JC-4s has two antenna ports, so you can use a longer wire for the low bands and a shorter one for the higher frequencies. At the moment what I use the two antenna connectors is actually changing between a horizontal and a vertical fishing rod :) Polarisation does make some difference at times.