Ten-Tec Omni Transceiver PTO Lubrication – Super Easy Method

The following PTO lubrication method can potentially save a day of work, so it should be worth a try. However the following practice for the Ten Tec Omni-D Series-C transceiver has not been endorsed by the company service department.

If the PTO frequency can be changed however such tuning offers resistance or feels rough, then the shaft bearing can be oiled. But if the PTO tuner mechanism is immobile, pull the PTO brick from the chassis and either clean with solvent and re-grease it or install a PTO re-build kit. Beware that the rebuild is not an easy task.

Oiling PTO Bearing
1. Obtain a small quantity of marine outboard lower unit oil, which is a good 90W lubricant. The original Ten-Tec grease has dried and hardened, but this heavy oil should blend in and soften it. It was chosen for long service life and being least likely to drip out.

2. Use a small Allen wrench to loosen the hex screw and remove the main tuning knob.

3. Gently pry the graduated dial from the tuning shaft.

4. Stand the transceiver on its rear to obtain gravity assistance in oiling the PTO shaft. Keep the radio turned vertically until all lubrication activities below are completed.

5. With aid of a flashlight, dip a toothpick into the oil and deposit about 6 drops into the groove, where the shaft enters the PTO bearing.

6. Place about 2 drops of oil on the junction between the small and large tuning shaft sections.

7. Install the main tuning knob, but not the graduated dial. Place the knob on just far enough for the hex screw to engage the shaft. Keep an eye on the larger tuning shaft behind the knob.

8. Rock the knob back and forth, while gauging the resistance. Actual tuning is working properly, only if the larger shaft visibly rotates. When tuned near a band edge, don’t force the PTO shaft to turn or mechanism damage may occur.

9. If rotation resistance is noticeably reduced, then you are on the right track. Rotate the dial through its full range about 10 times and feel its characteristics.

10. If results are positive, remove the main tuning knob and place about 4 more oil drops into the shaft groove. Reinstall the knob and again rotate tuning through its full range about 10 more times. But cease any extra oiling because the excess may drip through onto the circuit board.

11. Reinstall the graduated dial and main tuning knob. But don't attempt to force the graduated dial onto the PTO shaft or you’ll probably break something. Instead, utilize the safe procedure below.

Re-Greasing  PTO Bearing
Original lubricant that Ten-Tec installed in the PTO assembly usually hardens over time. Consequently the dial mechanism becomes immobile and the PTO can’t change frequency. Therefore the old lubricant should be removed and replaced with fresh grease. Utilize cotton swabs and 90% isopropyl alcohol to clean old lubricant from the PTO main bearing housing and associated spring assembly. Caution, acetone solvent will damage the plastic PTO parts. Re-Lubricate the PTO assembly, as follows.

Ten-Tec engineers designed the PTO to use open gear grease because it is tacky and stays in place when the main tuning knob is rotated. But if thinner consistency grease is substituted, it tends to run out over time. Consequently, premature wear to the bearing race and/or inner drive shaft will result.

Consider utilizing marine wheel bearing grease because it’s tacky and functions well in open boat trailer wheel bearings.

Safely Re-Installing Dial Skirt
Utilize a 24 inch piece of dental floss as a tool. Bend the floss into a U-Shape and hook it over the tip of the friction clip behind the dial. Pull the string to open the clip and then safely press the dial back in place.

Ten-Tec Omni Transceiver - SWR-TR Board 80450 - Problem/ Trouble/ Defect/ Repair

Ten-Tec Omni Model-D Series-C Amateur Radio Transceiver

Possible Electronic Defects* with SWR-TR Circuit Board 80450

*SWR Metering/ Power Output; Suspect D1

*Modulation ALC; Suspect D2

*Antenna Relay Inoperative; Suspect D3

*Insensitive Receiver; Suspect D4 and/or D5

One or more of the above issues tend to occur whenever the transmitter is loaded into a mismatched antenna with high standing wave ratio (SWR). The most common problem is a short-circuited diode D1 and/or D2.

Rather than expending time in determining specific defects, the author suggests replacing all five diodes. Be careful to install the diodes with the cathode band oriented correctly.

Place an indelible marker "dot" on the printed circuit board at the banded cathode end of all five diodes before removal.

Reference Documentation
Ten-Tec Omni-D Series-C Transceiver
SWR-TR  Board
Ten-Tec P/N 80450
Manual Pages 3-52 and 3-53

Printed Circuit Board Repair
Replace all diodes on the SWR-TR Board
Diodes, D1, D2, D3, D4 & D5
Ten-Tec P/N 28001
Generic P/N  1N4148 / 1N914 Silicon

Restring Ten-Tec Model 243 Remote VFO - Clarified Details with Labeled Photo

This revised procedure is based on the Ten-Tec method and has been clarified with extra details and a labeled image. Reference https://www.tentec.com/?p=1169

When the knob is rotated clockwise, the dial string is wound on the PTO drive shaft to pull the pointer toward the right side of scale. When the knob is turned counter-clockwise, elastic cord takes up string slack and pulls the pointer toward the left side of scale.

Procedure

1. Remove the front panel, as per manual.

2. Turn the PTO knob fully CCW to the low end of band. Turn the Mechanical Zero knob to midrange.

3. Make a very small loop and tie a secure knot in the Dacron string. Leave a 1 /2 inch tag to allow for knot slippage. Place the small loop around the pin on the PTO shaft.

4. Run the string CCW only once around the PTO shaft. NOTE: If the pin is on top of the shaft, the string will only need to go part way around the shaft. If the pin is on the bottom of the shaft, run string 1 full turn around the shaft.

5. Run the string down & under the plastic pin on the Mechanical Zero adjust knob. Then continue to the right under pulley #l up the right side and up around pulley #2. Then go across the top around pulley #3. The dial pointer should be placed on the string just touching pulley #3.

6. After passing pulley #3, go down and around pulley #4. Tie the Dacron string to the elastic cord at about l inch from pulley #5. Tie this knot securely and you may need to put a dab of two-part epoxy glue on the knot, to keep it from slipping.

7. Run the elastic cord over and around Pulley #5 and then back across the panel around Pulley #6.

8. Stretch the elastic cord about 1 inch & tie it to the solder lug, located on the screw immediately to the left of the PTO shaft.

9. Turn the PTO shaft completely through its range, while noting that the dial painter doesn’t bind or turn out. If the pointer stands out from the panel, flip the pointer up & over one or more full turns as necessary. This will prevent it from catching on front panel when it is installed.

Foot Notes
1. The following materials are needed for dial string mechanism repairs; 26 inches of Dacron string and 12 inches (relaxed) of elastic dial cord.

2. Ten-Tec insulated the front panel printed circuit board with tape. By age failure, the tape may be detaching to possibly hang-up the dial string/pointer mechanism. To solve this problem, remove the old tape and replace it with a double layered piece of 1.5 inch width clear packing tape. Trim around the shaft cutout to fit and run it fully across the panel, but don’t overlap the visible dial scale.

3. Don’t try to force the graduated dial onto the PTO shaft or you’ll probably break something. Instead, utilize a 24 inch piece of dental floss as a tool. Bend the floss into a U-Shape and hook it over the tip of the friction clip behind the dial. Pull the string to open the clip and then safely press the dial back in place.

4. After reassembly, the dial string/pointer mechanism may tend to hang up. Details follow for adding about 1\8 inch spacers to solve this problem. Obtain four hex nuts that have slightly larger holes than the mounting screws. If necessary, run a drill through the nuts to cut out the threads.

Temporarily install the mounting screws through the nut spacers into the four panel mounting posts. Mix two-part epoxy and glue the spacer nuts to the posts. After hardening, remove the screws and note that the spacers remain in place.

5. If the Mechanical Zero knob tends to bind on one side, widen that side of the aluminum trim slot, by about 1/8 inch with a hacksaw and file.

6. Original lubricant that Ten-Tec installed in the PTO assembly usually hardens over time. Consequently the dial mechanism becomes frozen and the PTO can’t change frequency. During a dial restringing operation, it is recommended to remove old lubricant and replace it with fresh grease. Utilize cotton swabs and alcohol to clean old lubricant from the PTO main bearing housing and associated spring assembly. Re-Lubricate the PTO assembly, as follows.

Ten-Tec engineers designed the PTO to use open gear grease because it is tacky and stays in place when the main tuning knob is rotated. But if thinner consistency grease is substituted, it tends to run out over time. Consequently, premature wear to the bearing race and/or inner drive shaft will result. (In a pinch as an untried idea, consider utilizing marine wheel bearing grease because it's tacky and functions well in open boat trailer wheel bearings.)

 7. If storing the 243 VFO for a time, leave the dial tuned to the low end of band. This action relaxes the elastic cord, which should give it a longer life span.