eHam Forums => Elmers => Topic started by: K6ZL on May 17, 2009, 03:57:28 PM

Title: Gurgling sound TS-940
Post by: K6ZL on May 17, 2009, 03:57:28 PM
I've fought this problem for years in various '940's.  On SSB both the receive audio and I'm told the transmit audio gets a "gurgling" sound. Like fast FM'ing.  I've tried on my radios (I've owned 8 '940s) resoldering various points on the PLL board with no real "yes that fixed it".  Sometimes the problem would resurface leaving me to believe just disturbing things would cause a temporary fix.   Any ideas out there?  MY "7 mil" '940 has just started doing the problem.  Any help and or ideas much appreciated.  73, Ron K6ZL.

Title: Gurgling sound TS-940
Post by: K7AAT on May 17, 2009, 05:12:35 PM

  Gurgling sound?   Have you put it on your shoulder and tried burping it?

  Seriously,  that sounds like a tough problem to diagnose.  I can't come up with any good advise so wish you  Good luck.

  Ed   K7AAT


Title: Gurgling sound TS-940
Post by: KA7ZIS on May 17, 2009, 05:58:34 PM
Google Hits....

 Results 1 - 10 of about 27,400 for distorted audio in ts 940. (0.31 seconds)

Title: Gurgling sound TS-940
Post by: KA5IPF on May 17, 2009, 06:20:29 PM
Probably VCO-0 is having a hard time staying locked.

My fix is to remove the PLL board. Remove the shield around VCO-0 (front right corner of the board). Melt out all the wax. After removing all the wax resolder all the joints in the VCO paying close attention to the large black choke. At the same time if there is any potting compound on the bottom of the board, usually holding a small cap, remove it completely, the potting compound not the cap. Reinstall the shield making sure to solder it to the coil

Re-install and set to 7.5v at the TP. If it is stable pot with hot glue, don't go crazy just enough to stabilize the parts. Reset the voltage to 7.5 after it has cooled down. So far, knock on wood, I've never had to re-do one for the same problem.


Title: Gurgling sound TS-940
Post by: K4DPK on May 17, 2009, 09:53:48 PM
PLL coming un-locked.

Probably due to the potting resin used to mechanically stabilize components in the VCOs, which everyone realizes now was a mistake.

Good luck.

Phil C. Sr.