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1775 balun problems

If there is a problem with the balun it can be tested this way.
Attached are photos of how the balun should be assembled on the inside of the box.

You may test the balun with a ohm meter.
   The center of the 239 connector should measure  little or no resistance to one of the output wires.
   The ground or shield of the connector should measure   little or no resistance to the other output wire.    The two output wires should not show any connection to each  other whatsoever.  The  SO239    also should not show any connection between the center pin and the shield.

A visual inspection should also be able to find any assembly problems.
   The balun is simply a piece of coax with a SO239 on one end, the center pin of the 239 should be
   connected to the center conductor of the coax.   The shield of the coax should be connected to one of the
   mounting holes on the 239 via a  small piece of buss wire.

   On the other end of the coax,  two bare copper wires are connected.  One is connected to the center conductor of
   the coax and the other is connected to the shield.    Each of the bare wires should exit each side of the box without
   touching one another.

About 48  beads are placed on the coax in 3 sections and  the coax is folded to fit inside the box.

To check the balun with a 249 antenna analyzer,  place a 50 ohm resistor across the 2 output wires of the balun without it
connected to the antenna.   Connect to the 249 to the coax connector of the balun. It should read close to 1:1  swr  on all the Hf bands.  The resistor used must not be a wire wound or any other inductive type.
Article details
Article ID: 58
Company: MFJ
Date added: 2017-01-12 14:18:51
Views: 71

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