Unlock Optimal Antenna Performance with The GRA-RWSM HF Antenna RF RFI Choke Coil Coax

I was reading some other reviews citing negative or subpar performance in this RFI choke and maybe I am misunderstanding something here. I am by no means an expert on RFI chokes or radio theory, but I would like to share my experience in what this product did manage to do quite well for me.I was looking for a way to eliminate RFI traveling down the feedline back to the radio, coined as "RF in the shack" to some ham operators. I have a PMR-171 backpack radio that I am using an end-fed antenna with 66 ft length of wire and on average no more than 30 watts of power on any mode/band. While my normal shack radio works without issues, the PMR-171 is more sensitive to stray RF. On certain bands when I key the PTT in AM mode, the radio immediately shuts off. On the bands I could get the radio to work I had issues using the USB sound card on the radio with my laptop. When the transmitter would key (and not shut the radio off), the USB interface on my laptop would fail. Therefore I suspected stray RFI coming down the coax into my radio causing the issue.I did a search on Amazon for an RFI choke and came across the GRA-RWSM HF Antenna RF RFI Choke Coil Coax. This is where maybe either I am misunderstanding its intent, or maybe other reviewers are misunderstanding. My understanding this would eliminate RFI coming back into the shack causing the erroneous issues with the radio and laptop, so I purchased this product. I received it today and it appears to have indeed resolve my issues. I am now able to use the PMR-171 without any issues. If i unhook and transmit without it the radio shuts off and laptop USB interfaces become problematic, since it appears RF causes the issue.I see many reviews complaining that it does NOT eliminate noise well. I am able to confirm that electrical noise on the powerlines which I have a LOT of does not decrease or go away when adding this product inline. I do not know that this was the intent of the product. All I can say is if you have RFI in your shack, this product exceeded my expectations and eliminated that problem. Adding this choke in line also had a very tiny impact on SWR. A .1 higher or lower on most bands, but nothing that impacted performances. After hooking the choke in line, I made a contact within minutes 1400 miles away, so performance is great.Construction of the product is 8 out of 10 I would say. I don't see any defects or any issues with the parts and cabling used to make this RFI choke. Quite frankly for it to be small, I am impressed it was able to resolve my issue as I've seen bigger RFI chokes used in many applications. Because of its size, I don't know about the power rating of 500 watts, especially with digital modes and have no way to test. I believe for low power this product makes a great solution.

My FTDx10 has never seen such a noise floor once installed. I have been naively working my rig for over a year and recently realized I have a common mode current problem. This resolved it.I have since ordered another noise device from Polamar and misc toroids for my FTDx10, but have moved this GRA-RWSM choke to my QT80.Bottom Line: A necessary (?) component of your radio setup.

A coax jumper with ferrite beads is used as a choke to keep reflected RF from coming back down the antenna coax to your radio. You can install one at the antenna feed point or, if your antenna uses the coax shield as a counterpoise, near the radio. I use them all the time and they work well, particularly with the lower bands (40m & 80m).That said, this type of choke usually has 3 to 5 ferrite beads. This choke only has one so it isn't as effective above QRP power levels (5 to 10 watts). This one is small and it works so I keep it in my go-kit. If I'm getting RF back at the radio, it is easy to install. If the reflected RF is better then I know to use a better choke.

This choke exhibits a meager -3 to -5db of gain. In order to be effective for the purpose intended, it needs to have a minimum of -25db gain (25db of choking ability) on the frequency used. This item was swept with a vector network analyzer to assess its ability to choke common mode current. Pretty bad...

Great to use when coming off the antenna, idea for POTA use.

Being inexperienced with ferrites and RFI suppression, I purchased this for use on my HF radio, to eliminate some severe RFI that I was experiencing. I knew nothing about ferrite compositions and ratings, so I figured this choke of unspecified composition, might solve my problem. It did not noticeably improve the issue, and I ended up adding toroids and snap-on beads to everything close to the radio to try to solve the problem. I thought that with this product at my radio's feed point, that I was "protected" from RFI from the antenna.Eventually, I decided to try replacing this with a ferrite toroid, which I wrapped my feed line through a few times. I went from a 9 on my S-meter to a reading of 1! This product had made no noticeable improvement to my RFI levels, and given that it adds another connector to my line, it was arguably harming more than helping--though probably insignificantly. By trusting this product, I unnecessarily spent $80 on ferrites for my other cables that I didn't need.I can't say for certain that this product has no use. Perhaps it would be useful at the feed point of a dipole antenna, for example. Still, you could probably do better with a snap-on ferrite bead, at less cost, without adding another connector into your feed line.I will say that this product seems well built. The connectors are solid and appear to be high quality, and the product seems weatherproof. For certain applications, this might serve well, especially if local RFI wasn't high to begin with. Maybe I'll experiment with it for field use--but I'll probably just use a snap-on bead or toroid instead.

It looked so nice when I opened the package, but I was disappointed to find that there was no manual, no link to a manual, no theory of operation, no specifications and no schematic. Could it be just a few ferrite beads snapped on the coax and covered with shrink wrap? If so, it might be a bit overpriced. Or, could it include a beautifully wound RFC (Radio Frequency Choke) coil such as was on a radio that I had in 1956? I do not know. So, I will run a few tests on 20 meters, using SSB, with my IC-705 transceiver at 10 watts with a resonant antenna and no antenna tuner. At some time in the future I will try to update this review, perhaps including pictures after dissection. I regret that I do not have more/better information at this time.

Very happy with this, does its job