Repairing the magnetic base of a car antenna

May

2023

Repairing the magnetic base of a car antenna

УКВ

29 May 2023 16:58

I am sharing a very simple way to repair a magnetic base.

A magnetic base like Opek AM-1024 or Opek AM-1023 (purchased at the siriust.ru store), or Opek AM-1025 develops a problem over time - the edge of the foil begins to wear out and its edges become uneven, torn and sharp. You cannot place such a base on the roof - it will scratch the paint down to the metal. A similar problem is observed with magnetic CB antennas - but there, at the base, the rubber disk - the cover - breaks.

1problem

Repair of the magnetic base of a car VHF antenna

The following materials will be required
1) double-sided tape

2) a piece of plastic film or rubber measuring approximately 120 x 120 mm.
3) scissors

We try the film to the diameter of the base.
I glue 3 pieces of double-sided tape to the plane of the magnetic base, directly to the foil.
Using scissors, I cut a circle from the film along the diameter of the base.
To better secure the edges of the film, you need to cut 6 small pieces of tape and glue them to the base
I remove the protective paper from the double-sided tape and stick the film on
The renovation is complete.

Checking the SWR of the Opek VU-1503 antenna on the Opek AM-1024 magnetic base

144 MHz band - standing wave ratio of Opek VU-1503 tuned antenna
7swr144

433 MHz band - standing wave ratio of Opek VU-1503 tuned antenna
8swr435

Graph of SWR (SWR) 87.5 - 450 MHz in more detail (click on the picture to enlarge it)

Connecting the cable to the radio station - cable assembly from SMA to UHF connector.
vhf-adapter

The adapter SMA plug - PL-259 plug (UHF) was ordered from a Chinese store on Aliexpress.
baofeng-cable

One SMA “barrel” was also used, which is available for purchase both on AliExpress and on the Juno market.
baofeng-display

Result

For transmit, the 144/433 Opek UV-1503 antenna performs exceptionally well. I see a signal on the WebSDR waterfall.
In terms of reception in the city, the Baofeng UV-5R radio station, frankly speaking, does not work very well, for a rating of 3 - deep QSB is possible. The reason is a drop in sensitivity due to overload of the input, which has no filters. The radio station can operate close to an amateur radio repeater (no further than 10 km). Of course, using an external car antenna significantly increases the maximum operating range of the radio.

This repair method can also be used for the base of a CB antenna.

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