MFJ-918BP, MFJ-2919BP, and MFJ-2920BP 1.5 kW, 1.8-30 MHz Portable Balun Introduction:

Without a balun, the outer surface of your coax shield provides a common-mode path for transmitted RF to flow from the antenna down to your operating location. Here, it can disrupt or damage sensitive electronics and, if severe, may even change the antenna's radiation pattern, distort your transmit audio, or cause a painful RF burn. On receive, the process is reversed, with stray locally generated carriers and "hash" traveling up the cable to the feedpoint to raise the noise floor and cover weak signals.

Description:

The MFJ-918BP, MFJ-2919BP, and MFJ-2920BP are especially packaged to provide balun protection for portable installations. Antenna wire or ladder line is connected to the PVC housing using color-coded 5-way binding posts for rapid installation and removal. Color coded terminals indicates the DC path through the MFJ-918BP (red = center conductor, black = shield). Note that the MFJ-2919BP and MFJ-2920BP have internal transformer connections that appear as a DC short between antenna terminals. On the inside, high permeability ferrite beads are installed over RG-303 Teflon coax to ensure high power handling, maximum suppression, and minimal signal loss. Chemically welded PVC construction guarantees long life under adverse environmental conditions. Coax attaches to a premium grade Teflon SO-239.

Models: [ ] MFJ-918BP:

A 1:1 ratio 50-Ohm current balun designed to minimize losses and deliver superior suppression over the entire HF range. Dipole or G5RV feed connects directly to 5-way terminals.

[ ] MFJ-2919BP:

A 4:1 ratio transmission-line transformer style balun designed for 200-Ohm loads. Especially adapted for portable folded dipoles and OCFDs.

[ ] MFJ-2920BP:

A 9:1 ratio transmission-line transformer design for 450-Ohm applications. May also be used for transitions to ladder line.

Installation:

The PVC balun enclosure may be secured with a hose clamp, taped, or tethered to any portable mast, post, or tower to serve as a center insulator for a temporary antenna. When installing, always support the balun enclosure vertically with the weep hole facing toward the ground to ensure proper drainage.

Important Warning: To prevent accidental death or serious injury, never install an antenna where it can contact power lines. Also, to prevent dangerous RF burns, keep energized antenna surfaces out of reach to humans and animals.

L

IMITED

12 M

ONTH

W

ARRANTY

MFJ Enterprises, Inc. warrants to the original owner of this product, if manufactured by MFJ Enterprises, Inc. and purchased from an authorized dealer or directly from MFJ Enterprises, Inc. to be free from defects in material and workmanship for a period of 12 months from date of purchase provided the following terms of this warranty are satisfied.

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The purchaser must retain the dated proof-of-purchase (bill of sale, canceled check, credit card or money order receipt, etc.) describing the product to establish the validity of the warranty claim and submit the original or machine reproduction of such proof of purchase to MFJ Enterprises, Inc. at the time of warranty service. MFJ Enterprises, Inc. shall have the discretion to deny warranty without dated proof-of-purchase. Any evidence of alteration, erasure, or forgery shall be cause to void any and all warranty terms immediately. MFJ Enterprises, Inc. agrees to repair or replace at MFJ's option without charge to the original owner any defective product under warrantee provided the product is returned postage prepaid to MFJ Enterprises, Inc. with a personal check, cashiers check, or money order for

$7.00

covering postage and handling. This warranty is

NOT

void for owners who attempt to repair defective units. Technical consultation is available by calling the Service Department at 662-323-0549 or the MFJ Factory at 662-323-5869. This warranty does not apply to kits sold by or manufactured by MFJ Enterprises, Inc. Wired and tested PC board products are covered by this warranty provided

only the wired and tested PC board product is returned.

Wired and tested PC boards installed in the owner's cabinet or connected to switches, jacks, or cables, etc. sent to MFJ Enterprises, Inc. will be returned at the owner's expense unrepaired. Under no circumstances is MFJ Enterprises, Inc. liable for consequential damages to person or property by the use of any MFJ products.

Out-of-Warranty Service:

MFJ Enterprises, Inc. will repair any out-of-warranty product provided the unit is shipped prepaid. All repaired units will be shipped COD to the owner. Repair charges will be added to the COD fee unless other arrangements are made. This warranty is given in lieu of any other warranty expressed or implied. MFJ Enterprises, Inc. reserves the right to make changes or improvements in design or manufacture without incurring any obligation to install such changes upon any of the products previously manufactured. All MFJ products to be serviced in-warranty or out-of-warranty should be addressed to:

MFJ Enterprises, Inc., 300 Industrial Park Road Starkville, Mississippi 39759 USA

and must be accompanied by a letter describing the problem in detail along with a copy of your dated proof-of-purchase. This warranty gives you specific rights, and you may also have other rights which vary from state to state.