Pages: [1]   Go Down

Author Topic: FT818 - an odd problem  (Read 274 times)

M6EES

  • Member
  • Posts: 235
FT818 - an odd problem
« on: September 09, 2022, 05:06:32 PM »

My FT818 is only about 6 months old and lightly used.

There is some kind of connection problem at the rear antenna socket.

Hard to explain, ....but if I insert a PL259 and screw it on almost but not quite fully (say 97%)....then waggle it a bit it flickers between about an S6 noise floor and zero noise floor...with strong stations not moving the S meter. Then when I fully tighten the PL259 it settles on either the S6 or 'zero noise floor' state.

After a month of soldering and resoldering PL259 connectors I have realised today that it is a problem with the radio and not the coax or PL259S. I have the same issue with all 5 of my lengths of coax.

It's a long drive back to the ham store and I fear this is going to be a trickly one to demonstrate. So wondered if anybody here might know what could be the problem ?
Logged

N6JPA

  • Posts: 8
    • HomeURL
Re: FT818 - an odd problem
« Reply #1 on: September 09, 2022, 05:23:10 PM »

Contact Yaesu to send the radio in for analysis. The Ham Store would just ship it Yaesu any way.
Logged

N4ATS

  • Member
  • Posts: 1416
Re: FT818 - an odd problem
« Reply #2 on: September 10, 2022, 07:26:45 AM »

Are the tangs in the SO-239 spread apart very wide? i.e when you screw in the PL-259 , are you SURE the pin is hitting the tangs? The problem you are describing is a common issue when the SO-239 spreads and the pin of the PL-259 goes right down the center and does not touch. This make the S meter go bonkers
Logged

W9MT

  • Member
  • Posts: 25
Re: FT818 - an odd problem
« Reply #3 on: September 20, 2022, 11:29:30 PM »

I had a similar problem with the SO-239 connector in an MFJ-249 antenna meter. Sometimes the VSWR would just whack the single meter on the device between a low reading and "infinity to one". In that device, I traced the "wonkiness" to cracked solder between the pc board's solder tabs and the center pin of the RF connector. Sometimes it would touch and complete the circuit connection, and sometimes the cracked solder was enough to do a total disconnect.

I don't remember if the center pin of the rear antenna connector in the FT-817/818 radio family solders directly to the main board or not.

One other thing you could try is to change the menu setting for which bands use the front BNC or rear UHF style connector. If front connections fix the "wonkiness", then most of your radio is exonerated and the problem is solely at the RF connector on the rear.

Good luck on your quest to exorcise this gremlin.

Tony (W9MT)
Logged
Pages: [1]   Go Up