PTO Repairs & Fixes

N1EU comments: 1)After disassembly, you will have two very small black plastic pieces: the wedge ("O") and the ramp ("G"). I almost thought they were plastic shrapnel that had broken off the pistol plastic. The diagram does show enough for you to orient them properly and assemble them. 2)The only step I had real difficulty with was at the end of assembly - securing the nuts on the screws holding the end cap on. There's more clearance on one side and I put that nut on first. I then secured the PTO in a vise so I could push the other screw in to expose maximum number of threads. I could then just barely get the 2nd nut on while holding with needle nose pliers.

From the Ten-Tec Reflector May 7, 2002

I Just finished cleaning one of my Corsair II PTO's recently and I have a few thoughts regarding the process. Ten Tec sells a kit for approximately $20.00 if you want a complete set of new mechanical parts for the rebuild. However, most of the time simply cleaning the existing parts works fine and may give the same longevity results as replacing the parts, IMHO. I believe where the brass PTO shaft is held in place by three steel ball bearings in the front of the PTO is where most of the brass filings that impair performance are generated. It is my belief that after the shaft has worn some, it does not contribute as much debris from the filings and may last as long as a new kit, again, IMHO. I have cleaned a number of PTO's over the last 5 years and they are all still going strong. I do this for a few friends and myself. I have 6 Corsair II's and they are all EXTREMLY EXCELLENT RIGs ! !

The following are some suggestions with a little humor that may save you some grief as you rebuilt your unit. It is not difficult but can be a little tricky if you don't make a few notes. I do recommend purchasing the PTO Kit from Ten Tec as it is contains an excellent internal drawing of the PTO, a complete set of mechanical parts and some high viscosity grease, as well as reassembly instructions. Only $20.00 or so while supplies last; who knows if the parts will be available in 5 or 10 years.

To get the PTO out, you will need to take the front panel off to get to the screws in the front of the PTO. Don't try to cut corners here, just take the front panel completely off. Be careful to not scratch the FP when taking the mic hardware off. The meter leads go to a connector on the topside of the unit and can be disconnected there. This also gives you an opportunity to clean the 5 toggle type switches with a good cleaner such as DEOXIT. This is an excellent time to clean the front panel with all of the knobs out of the way. The front panel comes off fast and look at the Corsair II book for information on getting the dial skirt back on. If you clean the Plexiglas piece, use a soft cotton rag and a little diluted 409, half water and half 409, this is also good for cleaning the knobs. A discarded toothbrush can really clean the knobs and give the Corsair that fresh, just out of the box look. If you are careful and take your time the front panel can be off and out of the way in about 10 minutes.

Next: get a note pad and make notes of how you proceed from this point. You will not regret this simple step and you could go nuts if you don't take the time to document your moves or worse, damage the unit. Before proceeding with the rebuild, take a few precautionary steps and the job will go smoothly. Allow around 2 hours the first time and half that the next time. I would rate this job as easier than rebuilding a carburetor with less aggravation and unlike the family car carburetor, you can do the rebuild inside without breaking your back.

I will defer to Ten Tec's PTO Kit instructions for the actual reassembly information but the following may be helpful supplemental information.

  1. Disconnect the phone near your work area ! ! ! Otherwise, some telemarketer will try to sell you a Time Share or trip to Florida exactly at the point when you are trying to reinsert the little pin that goes back into the rear of the PTO shaft. I don't know how but they always know exactly when to call.
  2. Take a white towel and stretch it out over a work table and get a comfortable chair, don't even think about doing this job standing up.
  3. Bring a bright light to the area, very important step.
  4. Tell your wife and children that you are not to be disturbed for the next two hours unless the house is on fire and if so allow enough time to get all of your coveted Ten Tec gear outside. Oh yea, be sure the kids get out as well !!!
  5. Put a sign on the front door letting the Jehovah Whiteness people know that you are already saved but both of your neighbors are HELL-Bound and need their help desperately. Your Neighbors may start cutting their grass at 5:30 AM on Saturday mornings to get back at you but your PTO will be working perfectly and you will be up anyway snagging a new DX contact.
  6. Put the Cat, Dog, lizard and especially any annoying, loud birds outside. After thePTO has been reinstalled and the Corsair II is working great, leave the Bird outside; the Corsair II will surely work better as a result. I had an African Gray Parrot that liked to mimic CW during contest. This QRM was settled once the bird found a new and loving home. Hope the new owner liked sloppy, left footed CW.
  7. One of those magnets on a wand is handy if you happen to drop one of the steel ball bearings, springs or locking pin on the carpet. Sorry but the magnet will not help with the brass parts no matter how much you disagree with the laws of Physics. You will also need a #1 and 2 Phillips screwdriver, needle nose pliers, lots of low lint, shop towels. I like the blue ones from the Auto Stores. Other items needed are Q-tips, a small 1/4 inch open-ended wrench, 71% Isopropyl Alcohol. Don't clean the pistol or other plastic parts with the Alcohol just the metal items. I cleaned the Pistol and plastic parts with a Q-tip and a water moistened towel. You will need a few drops of Super Glue such as Radio Shack Future Glue, part number 64-2331. Ten Tec uses high viscosity axel grease such as Exxon's, Unirex N-2 and enough to do several PTO's comes with the Ten Tec kit. I prefer using 1 Synthetic Universal Grease from Mobil, bar code 71924 96102. This product is available from automotive stores for less than $5.00 for 12.5 ounces. This grease is optimized to minimize wear while working under very high temperatures and pressure. I can say that I have not observed any wear between parts using this product for several years and absolutely no CW chirp, at least chirp generated by the PTO.
  8. There is a little locking pin that has to be removed and reinstalled in the PTO shaft. I use a worn, and very small diameter Allen wrench and the butt of ascrewdriver to tap the pin out. Just gentle tapping is all that is required and once the pin starts moving, it can be pulled out with needle nose pliers. To reinstall the pin GENTLY grip it with a small pair of wire cutters and once started, press the pin in place with a miniature pair of channel lock pliers.This is the worse part of the rebuild and isn't that bad.

If you happen to have a paper shredder under your work area, either remove or empty it before disassembling the PTO. Finding the steel ball bearing in a shredder full of paper is time consuming, believe me ! ! ! Same rule applies to waste baskets or boxes of hardware.

With preparation accomplished, remember to make notes on how the unit comes apart and the placement of the parts. As mentioned earlier, the rebuilt kit from TenTec can be a lot of help with instructions and drawings. Without it, proceed very carefully while disassembling and reassembling the PTO.

Once accomplished the Corsair II is again a joy to operate and should give three to five or more years of excellent service. Your wife and children will be proud of you for being able to fix something and your friends will be impressed with your MENSA like intellect. Expect a promotion and large raise at work, after all, if you can rebuilt a PTO in one of the worlds most excellent CW rigs, you are certainly a person of great character and worthy of all praises and rewards afforded by our society. Well, at least you will enjoy using the your Corsair II…

Glenn WA4AOS

Just one additional suggestion. Work in a tray with raised sides to slow down the rolling parts leaving.

73, Jerry, K0CQ

December 22, 2003

There's a trick to getting the PTO out of the Omni-D. Here's what Ten-Tec advises:


  1. Remove top, bottom and front panel as per pages 3-1 and 3-2 in your manual. Remove extrusion strip.
  2. Remove Vox board control nuts and screws or nut from rear end of Vox board. (leave wires on). Swing Vox board back and out of the way.
  3. Ttrim off the EXCESS insulating paper from the bottom cover of the PTO. Use caution not to cut any wires.
  4. Replace the Vox board- PTO will be removed thru the top of the unit.
  5. Remove the brace from the top center of the rig.
  6. On DIGITAL models- Remove the 4 screws from the front which hold the counter assembly to front sub-panel. Swing the counter assembly back and out of the way.
  7. Note location of wires on PTO and unsolder same.
  8. Remove the 2 screws holding the PTO to the sub-panel. Remove PTO by lifting rear up and out first.
  9. Rebuild PTO as per instructions provided. Clean the mating surfaces on PTO and inside sub-panel.
  10. Re-assemble rig and align as per manual as needed.

73 and good luck, Mike -N4NT-

July 2, 2003

A friend of mine sprayed the PTO in his OMNI C with WD40. I worked great for awhile and then quit altogether. When he brought it to me I took it apart and found it was full of fuzzy green stuff that apparently came from a reaction between the WD40 and the brass parts. Another friend who is in the Canadian Navy says they have been told not to use WD40 on anything brass.

Dave, VE1ADH

October 14, 2004

Dissolving PTO Grease

I've always had good luck with (cigarette) lighter fluid, the kind you'd use in a Zippo lighter. It's much less dangerous than gasoline (though still flammable), effective as a solvent, and leaves little or no residue. I have not experienced any plastic damage–so far–but I've only been using it for 20 years. The fluid is cheap and available at almost any supermarket.

73, K3YD

November 27, 2007

Although the real cure has been mentioned numerous times over the last 15 years or so, this question periodically comes up. The need is mostly to "re-lube" not rebuild, because the original grease has hardened and caused the vernier to slip. Needless labor is done when not necessary.

  1. Set TT PTO rig (all models) on it's back with front panel up.
  2. Using small allen wrench remove main tuning knob.
  3. Remove felts to expose the shaft entry point into PTO.
  4. Drip denatured alcohol into this entry point and turn outer and inner shafts until they free up. Turn from end to end of range many times.
  5. After a few minutes apply Tri-Flow bicycle lubricant (Teflon based) to same area and turn shafts in same fashion.
  6. Replace felts and tuning knob.
  7. Don't expect shaft to freeze up ever again. (unless you store the rig in your attic for 20 years) :-)

I have done this to no less than eight TT PTO sets over the years and the problem has never recurred.

Tri-Flow is available at most bicycle shops.

Perry w8au

November 29, 2007

I haven't seen this mentioned in any discussion of re-builds, so I guess I will.

Apart from the well-known "marble rolling through chewing gum" effect that the aging grease has on operation, there's one other thing I've noticed over years of repairs. The little plastic thrust-bearing cup on the back side of the PTO box has a tendency to stress-relieve over time. When this happens, the pressure on the shaft, along with the pressure the orbital balls should have against the race in the planetary drive, is reduced. Loss of this pressure is what causes the drive to slip. I have noticed, almost without exception, deformation on the "ears" of the thrust cups in afflicted PTOs.

There are usually a couple of washers between the thrust cup and the PTO housing. I move these from there, and put them under the heads of the #4 screws, so the pressure between the planetary bearings and the brass race increases, because the compression system is about .012" shorter.

This is, of course, after all the old grease is removed and a suitable replacement lubricant is applied.

I've never seen deep grooves worn into the races. Given the fact that the assembly is lubricated, I imagine it would take an enormous amount of use to do that, especially since the relatively soft plastic thrust cup is exerting all the pressure.

Your mileage may vary.

Phil C. Sr.

PTO Rebuild Grease

September 3, 2002

About 3 years ago I rebuilt several PTO's using Phil Woods bicycle grease. It was highly touted as being a great grease.

The one of those PTO's I was using lately (in a Triton 544) has gotten squirrely to tune – acts like the grease has gone or is going bad. SO, I don't recommend that grease for this application.

Once I talked with Garland down at Ten-Tec about grease and he told me they just got it down at the co-op. I don't know what kind they got at the co-op, but it sure does last better than my fancy stuff did.

73, Mike N4NT

December 29, 2004

I just finished cleaning and re-greasing my PTO using Mobil 1 Synthetic Grease (available at Auto Zone). Prior to that, I did another PTO using White Lithium grease (available from Sears and bicycle shops). And before that, I used the Ten-Tec grease that came in a PTO rebuild kit. Since I don't know what the Ten-Tec grease really is, I'd prefer either the Mobil 1 or White Lithium grease. The White Lithium grease is a little thinner, and the PTO tunes a little easier, but both seem to work very well and I expect will last a long time.

73, ed - k9ew

PTO Stabilizer Board

From the Ten-Tec Reflector February 17, 2005

I installed K4DPK the VFO stabilizer in my Corsair II. It works with TenTec 580, 540, Triton, Corsair, and Omni series.

This is a high quality board that has a look and feel similar to the boards that are used in the Corsair II. I mounted mine vertically along the case edge, just to the right of the .25 filter position, using an existing hole in the chassis.

I have never been able to turn on the rig within 15 minutes of NET time and join the net without an excessive amount of fiddling with the main tuning knob. The stabilizer board fixed this.

Here are some drift comparisons with other transceivers for reference. Values are Hz from startup reference frequency after 15 minutes, 30 minutes then 40 minutes. Receive only.

Drake R4C 150 300 500
FT101EE 180 280 300
K2 (stock) 110 150 170
Corsair II 050 100 150

— Dividing line here for acceptable ssb/cw —

K2 w/TCXO 30 40 No further drift after 30 minutes
C2 w/Stab 30 50 No further drift after 30 minutes
OMNI 564 w/TCXO Less than 20 cycles
IC756Pro Less than 20 cycles

The Corsair II with stabilizer also drifted an additional amount (20-40 cycles approximate) when transmitting for 5 minutes or more, then returned to the original receive frequency after 5 or 10 minutes of cool down time.

I don't think this variance is from the PTO which is controlled, it is most likely from other circuits in the transceiver near the PA.

This would most often not be noticeable using stock ssb filters, but with the Inrad 2.8 filter and receiving (example Orion transmitter on wide), you can hear this small effect.

A note about TenTec PTO's. I had one that had a little jump in it, 50hz every 3 minutes or so that was pretty annoying on CW. Ten Tec worked very hard on this and ended up fixing it after selecting parts by hand, using trial and error for my repair. (This was on the second trip to the factory, and they DID NOT charge me at all for this work!) There can also be little glitches with the PTO itself after the grease dries up. I expect in both of these cases the stabilizer may mask those effects. I connected the power to the stabilizer to an RCA plug on the back of the Corsair II. It's a great way to determine how the rig is operating without the stabilizer helping it along.

That's the info from this qth, K4DPK (Phil) is also very accessible and helpful.

de WB8YQJ/6

PTO Hand Capacitance Effect Fix

From the Ten-Tec Reflector October 25, 2005

For anyone using a Ten Tec rig that has PTO tuning, here's good news… I was rebuilding the PTO in my Argosy 525, and decided to try grounding the tuning shaft to eliminate the sometimes irritating frequency change that occurs as you bring your fingers near the tuning knob on the older TenTec rigs. This might be more a CW issue, but perhaps it shows up in digital operation also.

I wanted some kind of a springy wiper contact, and I wound up using a piece of #22 copperweld wire. I wrapped one turn around a small drill bit to form a loop, and mounted it under the LEFT PTO screw on the inner front panel. I had to make a couple of bends to get the wire to lay on the larger diameter portion of the tuning shaft, making a half-loop at the "wiper" end to ride on the shaft. This grounding wire must clear the dial cord, but it must also avoid interfering with the outer front panel. It's easier than it sounds. And the best part is that it works! There is absolutely NO CHANGE in receive frequency no matter where my fingers are.

The next time you're doing a PTO rebuild, I highly recommend making this simple mod.

ed - k9ew

October 25, 2005

Two wires work even better. I've used small piano wire, AKA music wire.

Greasing the shaft where it passes through your wipers will reduce the problems caused by oxidation and corrosion over the years (which would not damage anything except the quality of the electrical contact.

73, Mike N4NT

October 25, 2005

What I have been using here in my shop is a couple of cut-down safety pins. The pins are cut to leave the circular spring "eye" and one long leg.

These are placed under the two #4 screws, as you did, with the one on the left having the leg come off at the top, and riding on top of the shaft, so that pressure against the shaft increases with tightening the screw.

Likewise, the RH contact is placed under the screw with the leg coming off the bottom and riding against the bottom of the shaft, so it tightens against the shaft when tightening the screw.


Phil Chambley, Sr.

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