---
product_id: 59851313
title: "MFJ RF Isolator Balun MFJ-915 Choke For Ham & CB Radio HF Antennas"
brand: "mfj"
price: "฿227"
currency: THB
in_stock: false
reviews_count: 1
url: https://www.desertcart.co.th/products/59851313-mfj-rf-isolator-balun-mfj-915-choke-for-ham-cb
store_origin: TH
region: Thailand
---

# 1.8-30Mhz range 50 Ohm impedance Stray RF elimination MFJ RF Isolator Balun MFJ-915 Choke For Ham & CB Radio HF Antennas

**Brand:** mfj
**Price:** ฿227
**Availability:** ❌ Out of Stock

## Summary

> 📻 Tune In, Block Out the Noise!

## Quick Answers

- **What is this?** MFJ RF Isolator Balun MFJ-915 Choke For Ham & CB Radio HF Antennas by mfj
- **How much does it cost?** ฿227 with free shipping
- **Is it available?** Currently out of stock
- **Where can I buy it?** [www.desertcart.co.th](https://www.desertcart.co.th/products/59851313-mfj-rf-isolator-balun-mfj-915-choke-for-ham-cb)

## Best For

- mfj enthusiasts

## Why This Product

- Trusted mfj brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Perfect Match:** 1:1 impedance ensures optimal performance with 50 Ohm systems.
- • **Easy Connectivity:** Compatible with coax cables featuring PL-259 connectors for hassle-free setup.
- • **Wide Frequency Range:** Designed for 1.8-30Mhz HF use, perfect for diverse applications.
- • **Enhance Your Experience:** Reduce TVI and enjoy clearer communication without disruptions.
- • **Say Goodbye to Interference!:** Eliminate stray RF from your amateur and CB radio antenna feedlines.

## Overview

The MFJ RF Isolator Balun MFJ-915 Choke is engineered to eliminate stray RF interference from amateur and CB radio antenna feedlines, ensuring a clearer signal and reduced TVI. With a frequency range of 1.8-30Mhz and a 1:1 impedance for 50 Ohm systems, this balun is compatible with PL-259 coax cables, making it an essential tool for any serious radio enthusiast.

## Description

The MFJ-915 RF Isolator is a 1:1 Current Balun designed to be placed in line with a 50-Ohm coax. The RF Isolator is effective from 1.8 to 30 MHz. It was designed to improve the performance of all amateur stations, fixed or mobile.MFJ-915 will reduce or eliminate stray RF often found on coax. This stray RF can cause burns and other problems with electronic equipment in ham-shacks and vehicles. Stray RF also results in a loss of radiated power from the antenna, which will lead to a great reduction in signal strength. Use of the MFJ-915 will increase the efficiency of all amateur stations.Its made up of 50 Ferrite Core Beads, placed onto a 13-inch piece of RG-303 coax. The coax and SO-239 connectors have Teflon(R) for maximum insulation and extended life of the product. The RF Isolator is enclosed in schedule 40 PVC pipe for maximum strength and protection.

## Features

- * Eliminate Stray RF from Amateur & CB Radio Antenna Feedlines.
- * Helps Reduce Interference & TVI.
- * For 1.8-30Mhz HF uses.
- * 1:1 , 50 Ohms; Accepts Coax cables with PL-259 Connectors.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Manufacturer | MFJ |
| Brand | MFJ |
| Item Weight | 10.5 ounces |
| Package Dimensions | 7.68 x 7.64 x 2.24 inches |
| Item model number | MFJ-915 |
| Is Discontinued By Manufacturer | No |
| Manufacturer Part Number | MFJ-915 |

## Product Details

- **Antenna:** Radio
- **Brand:** MFJ
- **Colour:** White
- **Impedance:** 50 Ohm
- **UPC:** 650619003109
- **Manufacturer:** MFJ

## Images

![MFJ RF Isolator Balun MFJ-915 Choke For Ham & CB Radio HF Antennas - Image 1](https://m.media-amazon.com/images/I/316p6KuMNwL.jpg)
![MFJ RF Isolator Balun MFJ-915 Choke For Ham & CB Radio HF Antennas - Image 2](https://m.media-amazon.com/images/I/21gKQG9Sx-L.jpg)

## Questions & Answers

**Q: Will this work for a balanced diopole to and unbalanced coax line ?**
A: Alfred E. Parker's article is a good one, but his answer is misleading.  In fact, the MFJ-915 CAN be used as a 1:1 current balun at the feed point of a resonant center-fed dipole, though it isn't mechanically optimal.  With an SO-239 adapter on the output, it will work for temporary antennas, and I've used it that way, but the MFJ-918, with the same internal design, is better suited mechanically for a permanent antenna installation.  Other companies make similar devices, including Balun Designs, whose prices are a little better than DX Engineering, while their quality is sometimes better than MFJ.
This is what is going on here (trust no one on baluns, including me; they are notoriously tricky to design or specify for a particular application):  A center-fed dipole, at resonance, will have a purely resistive impedance of 40 to 50 ohms, depending on details of construction and mounting height above ground.  Since this is close to the impedance your radio and coax want, you need no impedance transformation, merely a balancing of current at the feedpoint, which is exactly the same thing as blocking the common mode current.  A common mode RF choke IS a 1:1 current balun.  It can be placed at other points in the feed line as well, leaving the coax shield past that point as part of the antenna system, which is sometimes desirable as a counterpoise for odd, unbalanced antennas.  A dipole that is NOT center-fed or not at resonance will have different impedance, and may require an impedance transforming balun, like the common 4:1.  If you think you need one of those, to feed an off-center fed dipole, or a Windom, or a ladder line, check out Balun Designs website.  They explain which 4:1 design you want for each of those applications.
A note about the impedance of a center-fed dipole: You may find that the SWR is minimum slightly off resonance, this is because the resonant impedance is not 50 ohms for your particular antenna in its particular environment.  Off-resonance, the resistive component of impedance can rise to nearer 50 ohms, and offset the increasing reactive component, to give a minimum SWR.  It doesn't really matter much, but minimum SWR is often NOT at resonance, where the impedance is purely resistive.  I know, this can drive a person nuts, I keep re-reading this stuff every time I work with a new antenna or modify an old one!
Be cautious of power rating.  Under some circumstances, depending on antenna design and feedline length, a balun will end up dissipating a fair amount of power.  Make sure you have the correct balun type for the job, and that it is rated for enough continuous power input not to burn up!

**Q: Is this a low pass filter?**
A: No. It consists of ferrite rings surrounding 50 Ohm coax. It serves to add inductance reactance (increase impedance) to both the shield and center conductor between the antenna and the transmitter. The common use is to remove RF from the case or ground of the transmitter that causes RF burns while transmitting. it does not have any impact on the SWR or attenuation of signals. Often the transmission line is exposed to the strong fields from the radiator elements of the antenna and the shield of the coax tends to present RF on the shield. My antenna is very close to the rig and after installing the isolator, all burned lips have healed. if i can be any further help, you can call me 469-231-2784.Jerry WestW5YXR

**Q: Why are these so much more expensive on Amazon than they are everywhere else?**
A: Vendors may have different pricing, as they may sell more or less of any device, but that is up to the vendors. Not sure if you can negotiate pricing.

**Q: When you hook up the mfj swr analyzer to the antenna do you keep the if Isolator in line also while your reading the swr readings?**
A: Yes, it becomes part of the antenna system.

## Customer Reviews

### ⭐⭐⭐⭐⭐ did make things easier
*by B***S on 9 August 2023*

easy to install , helped greatly

---

## Why Shop on Desertcart?

- 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016
- 🌍 **Shop Globally** — Access 737+ million products across 21 categories
- 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price
- 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members)
- 🔒 **Secure Payments** — Trusted payment options with buyer protection
- ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews

**Shop now:** [https://www.desertcart.co.th/products/59851313-mfj-rf-isolator-balun-mfj-915-choke-for-ham-cb](https://www.desertcart.co.th/products/59851313-mfj-rf-isolator-balun-mfj-915-choke-for-ham-cb)

---

*Product available on Desertcart Thailand*
*Store origin: TH*
*Last updated: 2026-02-05*