Pages: [1]   Go Down

Author Topic: MFJ-5008  (Read 193 times)

NO9E

  • Member
  • Posts: 1124
MFJ-5008
« on: June 03, 2021, 08:02:46 AM »

I have MFJ-5008. Many hams reported the unit as very selective to pinpoint a specific isolator on a pole. Mine is very sensitive but not selective. Can hear crickets bit does not hear sparks very well. When pointed to an ultrasonic source, it shows multiple maxima. Did anyone experience similar problems?
Ignacy NO9E
Logged

W6QW

  • Member
  • Posts: 462
Re: MFJ-5008
« Reply #1 on: June 03, 2021, 02:23:22 PM »

Here's a coupe of suggestions to consider:

1. Try sniffing late at night as a number of the 40KHz emitting noise distractions may be dormant.  That may decrease some false returns.

2. If you have the ability to attach a portable oscilloscope to the audio output port (I use scopes in my vehicle powered by a 12VDC to 120VAC sine wave inverter), you will be able to visually discriminate between the various ultrasonic time-domain signatures.  Despite other interfering signatures, you should be able to see the 8.3mS arc-fault signature on the scope.  Using one's ear to discriminate between different signatures coming from the ultrasonic receiver is not very accurate.

I have some other suggestions but those would require modifications to the MFJ-5008.  If interested, email me per my QRZ email information.

Good hunting..

Logged
Pages: [1]   Go Up