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MFJ-1795W Vertical Antenna                                                                      Instruction Manual 

WARNING:  

Serious burns can be received with improper use of a soldering iron. 

 

[ ] 5.

  The wire should now be soldered to the center pin of the SO-239 connecter.  

 

[ ] 6.

  Remove the fiberglass tubing from the aluminum tubing of the assembled antenna by 

loosening the hose clamp.  Place the solder lug, under the hose clamp and retighten. 

 

[ ] 7.

  Insert the fiberglass tubing through the U-bolts and tighten the nuts.  This will make base 

installation much easier.  

 

[ ] 8.

  Adjust the wire length so that it approaches the soldering lug at the antenna feed-point.     

 

[ ] 9.

  Carefully solder the insulated wire to the solder lug. 

 

[ ] 10.

 Tighten the nuts on the U-bolts firmly. 

 

[ ] 11.

 Re-attach the antenna to the fiberglass tubing by tightening the hose clamp.  Remember to 

place the solder lug attached to the center conductor of the coax under the hose clamp 

 

[ ] 12

. Make sure that the aluminum tubing, the insulated wire, and solder lugs 

DO NOT COME 

INTO CONTACT WITH THE ANTENNA BASE

. Small readjustments of the 

fiberglass insulator may be necessary. 

 

REMOVING THE ANTENNA FROM THE BASE OR BRACKET 
 

The antenna may be quickly removed to be hidden from view.  This is easily accomplished by 
loosening the hose clamp at the base of the antenna shown in Figure 2.  Carefully pick up the 
antenna mast.  Be sure to watch for overhead tree limbs and other objects that could come into 
contact with the antenna during removal.  These objects could cause the antenna to become 
unbalanced and fall, resulting in personal injury and damage to the antenna.  Store the antenna in 
a safe place to prevent damage. 

FREQUENCY AND SWR ADJUSTMENT 

 
This antenna covers wider frequency ranges on the higher bands, and narrower segments on the 
lower frequency bands.  The 60-meter band has the narrowest range of operation (approximately 
100 KHz) and is the most sensitive to adjustments. 
 
The entire antenna must be accessible during initial tuning and testing. If the MFJ 

Ground 

Coupled™ 

Portable Antenna Base is used, attach the antenna to the base and place it in a 

location away from buildings or other objects that could affect the measurements.  If the portable 
antenna base is not used, it is best to install the antenna on a short, temporary mast or pipe. 
 

IMPORTANT:

  A suitable Ground radial system must be connected to the antenna 

mounting bracket if the Ground Coupled Portable™ Antenna Base is not used. 

11

 

Summary of Contents for MFJ-1795W

Page 1: ...l Instructions Before Operating Equipment MFJ ENTERPRISES INC 300 Industrial Park Road Starkville MS 39759 USA Tel 662 323 5869 Fax 662 323 6551 COPYRIGHT 2006 MFJ ENTERPRISES INC C Model MFJ 1795W VERSION 1A WARC Band Portable Antenna ...

Page 2: ...acitance Spokes 8 Loading Coil 30 Meter 4 17 Meter 4 12 Meter 4 Note This drawing is not to scale MFJ 1795W WARC Band Vertical Antenna Always Follow Assembly Instructions Mount Mounting Bracket 1 x 30 30 x 1 Tubing 5 x1 1 8 Tubing WARC Bands Vertical Antenna 1 ...

Page 3: ...g chart lists the power rating and the 2 1 VSWR bandwidth of this antenna Band Meters Power Watts Bandwidth KHz CW SSB RTTY 60m 700 1500 500 100 30m 1250 1500 750 300 17m 1250 1500 1000 1000 12m 1250 1500 750 2000 The weight and wind load of this antenna are 10 pounds and approximately two square feet respectively WARNING Improper installation and assembly can be hazardous Read these instructions ...

Page 4: ... INSTALLATION The MFJ 1795W was designed as a low profile portable antenna When combined with the MFJ Ground Coupled Portable Antenna Base the antenna will provide permanent or portable communications This is an ideal antenna for restricted locations However the antenna installation MUST be protected with non metallic fencing to provide personal safety and to prevent antenna damage The antenna can...

Page 5: ...g MFJ 1795W PARTS LIST As you unpack your antenna you should find the parts in the following list two 2 bundles of wire capacitance spokes eight 8 21 spokes and 14 36 spokes and two 2 spare 21 spokes 5 radiator 1 1 8 30 x 1 radiator 9 x 1 1 8 radiator loading coil assembly base mounting bracket hollow fiberglass rod insulator One Hardware Bag containing 4 1 5 hose clamps bag of short 6 32 stainles...

Page 6: ...itance hats or you will BREAK the fiberglass form If the terminal lugs loosen tighten the NUT on the lug STEP BY STEP PROCEDURE 1 Prepare a temporary work surface such as a table two saw horses or trash cans to be used while installing the parts onto the antenna 2 Sort out the parts you have unpacked into groups of similar parts Be sure all the parts are available 3 After examining the antenna par...

Page 7: ...2 into the 60 x 1 1 8 aluminum tubing See Figure 2 Fiberglass Insulator Solder Lug 60 x 1 1 8 Mast Pipe Antenna Feed Point Hose Clamp Figure 2 10 Place one of the hose clamps around the aluminum tubing and snug the clamp using a 5 16 nut driver The center conductor of the coax will be connected to the antenna using a solder lug placed under the clamp Refer to figure 2 11 Place one of the small pla...

Page 8: ...the next sets of rings 30M Again tighten these spokes as was done in step 9 See Figure 3 and Figure 4 14 Install four 21 capacitance spokes in the remaining two sets of rings 17 12M Again tighten these spokes as was done in step 9 See Figure 3 and Figure 4 15 Slide a hose clamp over the top radiator Mount the top coil assembly to the antenna by inserting the fiberglass insulator in the top radiato...

Page 9: ...are you installed Then mount the antenna on the short temporary tuning mast or the MFJ Ground Coupled Portable Antenna Base 17 Secure the mounting bracket to the fiberglass insulator as shown in Figure 5 Make sure the antenna mast does not contact the U bolts The next four steps may be skipped if the antenna uses the MFJ 1904 Antenna Base Figure 5 8 ...

Page 10: ...e the antenna by following the instructions under the section Frequency and SWR Adjustment 21 Mount the antenna in its permanent location Slight retuning and height adjustment may be necessary USING THE MFJ GROUND COUPLED PORTABLE ANTENNA BASE WITH THE MFJ 1795W The antenna base should be assembled using the instructions supplied with the unit The following instructions will explain the installati...

Page 11: ... Bushing SO 239 Anetnna Base 3 The plastic bushing supplied in the parts should be placed in the hole under the SO 239 connector 4 Now the 15 piece of insulated wire should be passed through the plastic bushing to the antenna feed point SO 239 Bus Wire Figure 7 10 ...

Page 12: ...ACKET The antenna may be quickly removed to be hidden from view This is easily accomplished by loosening the hose clamp at the base of the antenna shown in Figure 2 Carefully pick up the antenna mast Be sure to watch for overhead tree limbs and other objects that could come into contact with the antenna during removal These objects could cause the antenna to become unbalanced and fall resulting in...

Page 13: ...e spoke is removed install all the spokes and trim each spoke in 1 4 inch increments The spokes for each band should be cut to the same length Once the resonant frequency is found use the chart located under the section Tuning The Antenna section of this manual to estimate the amount of the spoke length to cut so that the antenna will resonate at your favorite section of the band CAUTION Always st...

Page 14: ... spokes equals approximately 500 KHz 17 M 1 trimmed off each of the spokes equals approximately 560 KHz 12 M 1 trimmed off each of the spokes equals approximately 570 KHz 3 Now tune progressively higher frequency bands by trimming the spokes Keep each set of capacitance spokes equal in size 30 meters must be the second HF band adjusted 17 the third and 12 meters last After adjusting 12 meters go b...

Page 15: ... If the manual does not reference your problem or your problem is not solved by reading the manual you may call MFJ Technical Service at 662 323 0549 or the MFJ Factory at 662 323 5869 You will be best helped if you have your unit manual and all information on your station handy so you can answer any questions the technicians may ask You can also send questions by mail to MFJ Enterprises Inc 300 I...

Page 16: ...er postage and handling 4 This warranty is NOT void for owners who attempt to repair defective units Technical consultation is available by calling 662 323 5869 5 This warranty does not apply to kits sold by or manufactured by MFJ Enterprises Inc 6 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 boa...

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