• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
  • A Winner has been chosen for the 2026 July 4th Retevis RA89R Giveaway! Click Here to see who won!

Cobra 139 LXR Capacitor question?

long night

Active Member
Jan 8, 2020
202
39
38
77
Hi to all. Can someone tell me which way the C-304 capacitor faces so I can install it with correct polarity. My radio has this capacitor missing so I have no guide.

Thanks to all Long Night
 

Hopefully this might give you some help.
If you look right between C304 and R305 there is a tiny little white '+' symbol.

That would suggest to me that the C304 pads are "side to side" (where R305's pads are vertical in this image, I am thinking that C304's pads would be there horizontally) and the one closest TO the resistor would be positive terminal of C304 and the other would be negative.

It would be prudent though to do a little pad/trace exploration.....
139XLR_C304.png

In this next snippet..... the POSITIVE side of C304.....connects RIGHT OVER to one of the ends of R305. You should be able to see that on the back side of the Power Supply PCB. If that pad with the + runs over to the resistor R305....Bingo! That is the positive pad for C304.

Schemo.png

Good luck.... let me know!
 
  • Like
Reactions: tecnicoloco
Hopefully this might give you some help.
If you look right between C304 and R305 there is a tiny little white '+' symbol.

That would suggest to me that the C304 pads are "side to side" (where R305's pads are vertical in this image, I am thinking that C304's pads would be there horizontally) and the one closest TO the resistor would be positive terminal of C304 and the other would be negative.

It would be prudent though to do a little pad/trace exploration.....
View attachment 45636

In this next snippet..... the POSITIVE side of C304.....connects RIGHT OVER to one of the ends of R305. You should be able to see that on the back side of the Power Supply PCB. If that pad with the + runs over to the resistor R305....Bingo! That is the positive pad for C304.

View attachment 45637

Good luck.... let me know!
Got
Hopefully this might give you some help.
If you look right between C304 and R305 there is a tiny little white '+' symbol.

That would suggest to me that the C304 pads are "side to side" (where R305's pads are vertical in this image, I am thinking that C304's pads would be there horizontally) and the one closest TO the resistor would be positive terminal of C304 and the other would be negative.

It would be prudent though to do a little pad/trace exploration.....
View attachment 45636

In this next snippet..... the POSITIVE side of C304.....connects RIGHT OVER to one of the ends of R305. You should be able to see that on the back side of the Power Supply PCB. If that pad with the + runs over to the resistor R305....Bingo! That is the positive pad for C304.

View attachment 45637

Good luck.... let me know!
Hopefully this might give you some help.
If you look right between C304 and R305 there is a tiny little white '+' symbol.

That would suggest to me that the C304 pads are "side to side" (where R305's pads are vertical in this image, I am thinking that C304's pads would be there horizontally) and the one closest TO the resistor would be positive terminal of C304 and the other would be negative.

It would be prudent though to do a little pad/trace exploration.....
View attachment 45636

In this next snippet..... the POSITIVE side of C304.....connects RIGHT OVER to one of the ends of R305. You should be able to see that on the back side of the Power Supply PCB. If that pad with the + runs over to the resistor R305....Bingo! That is the positive pad for C304.

View attachment 45637

Good luck.... let me know!
Hopefully this might give you some help.
If you look right between C304 and R305 there is a tiny little white '+' symbol.

That would suggest to me that the C304 pads are "side to side" (where R305's pads are vertical in this image, I am thinking that C304's pads would be there horizontally) and the one closest TO the resistor would be positive terminal of C304 and the other would be negative.

It would be prudent though to do a little pad/trace exploration.....
View attachment 45636

In this next snippet..... the POSITIVE side of C304.....connects RIGHT OVER to one of the ends of R305. You should be able to see that on the back side of the Power Supply PCB. If that pad with the + runs over to the resistor R305....Bingo! That is the positive pad for C304.

View attachment 45637

Good luck.... let me know!
Got it. Thanks for your help!!
 

dxChat
Help Users
  • No one is chatting at the moment.
  • @ BJ radionut:
    Scheduled for Jul 4, 2026 Saturday Live Streams:
    To celebrate the 250th birthday of our great nation. We are giving away not just one, but multiple antennas! The Grand prize is the CaHR-Tenna Hydra Antenna, along with several other antenna prizes that will be announced throughout the giveaway. Whether you're a new ham, portable operator, POTA activator, or an experienced HF operator, this is your chance to upgrade your station. Prizes Include: HRA Hydra Antenna (Grand Prize) Additional antennas from HRA More prizes may be added during the giveaway!
  • @ BJ radionut:
  • @ BJ radionut:
    CQ Worldwide VHF SSB/CW Contest: 1400Z, Jul 4 to 1400Z, Jul 5