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Author Topic: TS-930 Low power out on 40  (Read 2836 times)
KA9J
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Posts: 7




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« on: December 21, 2012, 04:53:10 PM »

My TS-930 has been sitting for about 5 years after I moved, but I've put up a vertical and I'm on operating again.   I had to dig out my Yaesu FT-101EE though, because the Kenwood only has about 2 watts out on 40 hooked to a dummy load.  On 20 it puts out over 100W into an external wattmeter.    On 40M, even though it's on a good (Heathkit Cantenna) dummy load, the 930's SWR meter pegs when you transmit.   On 20, it indicates an SWR of about 1.5, even though the reflected meter on the external wattmeter hardly moves.   The other bands work in varying degrees.   Some have lower power out, but not as low as 40, and their SWR indication is higher than 20M.   Any ideas?  BTW, the serial number is in the 4million range.

Frank  KA9J
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KE3WD
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Posts: 5694




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« Reply #1 on: December 21, 2012, 06:03:18 PM »

The Output Filters are the likely suspect. 

First thing to suspect in a rig that's been sitting without use is dry/dirty switch contacts and possibly relay contacts.  Deoxit spray on each switch and control internally, a wee bit in each and then rotate control or operate switch from end to end from six to ten times to mechanically wipe contacts while still wetted with the deoxit. 

Output filtering that uses relays, the contacts can sometimes be accessed and cleaned with strip of printer paper, sometimes wetting the paper with Deoxit and then hold the contacts closed on the paper strip while dragging it through the contacts to clean them.  Some very tiny relays may be such that replacing the relays is the way to go. 

When any rig has been sitting for any period of time, the switches and controls will dry out and can cause all sorts of problems unless cleaned and lubed as described.  This should be done before ANY further troubleshooting is done, and one should never assume alignment is an issue until all controls are cleaned properly.  A large percentage of the time this sort of cleaning can restore complete and calibrated operation.

A common problem.


73
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KA4POL
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Posts: 1921




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« Reply #2 on: December 21, 2012, 10:07:05 PM »

As has been mentioned, the relay contacts of the LPF might be involved. The 930 has a built in antenna tuner. There you also might find a problem.
Using a dummy load is a very good idea. It excludes any other external problems.
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KA9J
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Posts: 7




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« Reply #3 on: December 22, 2012, 06:41:22 AM »

Thanks both of you for your replies.     Something else that I saw one time was that I was turning the VFO and I heard a relay pick up.   The receive came up, and when I keyed it, it had more output power.    I'd say that the output filters  are  probably the problem.    This rig doesn't have a built in turner.   

Frank
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KA4POL
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Posts: 1921




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« Reply #4 on: December 22, 2012, 07:18:29 AM »

I guess I got it confused with the 930S which has the tuner built in.
Your symptoms really indicate bad relay contacts. A couple of switching cycles should improve them.
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KA9J
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« Reply #5 on: December 22, 2012, 08:09:53 AM »

Actually, I was wrong---it does have the antenna tuner, but it doesn't work.    I took the top cover off, and saw that the antenna tuner was installed.     The RED tune light was not on, but the switch was in the 'AUTO' position.   I moved the switch to 'THRU' and now I have 140W output, and the built in SWR meter agrees with the external meter.   I switched it back to 'AUTO' and the power went way down and the SWR meter was full scale.    I inherited this rig  about 8 years ago from my uncle (W9NRI) when he passed.   I used it, but all my antennas at my old house were resonant---so I never used the autotuner.    Somehow the switch got moved to AUTO, and the problem showed up.   I went digging through the service manual and found some additional paperwork between Uncle John and a guy that he sent the rig to for repair.     He'd found some solder joints that needed resoldering, and a lot of other things.   Uncle John had asked him to look at the auto tuner, but to get back to him with the cost of repair.     The receipt said that he'd checked the autotuner, but no more.   Maybe it's never worked.    I know that Uncle John used non-resonant antennas and an external tuner.

Any ideas what to check with the autotuner?    You hear a relay pick up when you turn it to auto, but the red auto tune light does not come on.   Also the indicated SWR goes up on all the  bands I checked. 
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KA5IPF
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« Reply #6 on: December 22, 2012, 10:25:58 AM »

The tuner in the 930 is automatic in that it tunes but it doesn't key the radio. Put the radio in Tune Mode, Carrier straight up, and Tuner in Auto position.

When you key the radio it should tune and stop when it reaches ~1-1. Have the Meter in SWR position. Then unkey. That is unless you have fried the relay or parts by putting 140w into it in an untuned condition. You have to do this for each band or within the band if you move around. It does not remember where you were last so each band change requires re-tuning.

Read the manual for correct operating procedure.

Clif
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KA9J
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Posts: 7




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« Reply #7 on: December 22, 2012, 02:16:05 PM »

Cliff, 

That did it.   I followed what you said and the motors took off and the onboard SWR meter dropped.    The manuals I have are the service manual which shows the physical layout and schematic of the tuner, and what I think is the operating manual.   It talks about everything else in detail, but the the proceedure for the auto tuner must have been on some other piece of paper, because I've looked cover to cover 3 times and didn't find it.    Thanks for your help.
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KA5IPF
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« Reply #8 on: December 22, 2012, 04:13:58 PM »

It's in the owners manual, not the service manual.

Clif
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KA4POL
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Posts: 1921




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« Reply #9 on: December 22, 2012, 11:11:34 PM »

Operating manual of the 930S has it on page 22, left column, para 5.
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KA9J
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Posts: 7




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« Reply #10 on: December 23, 2012, 11:52:02 AM »

Thanks for the help.    The rig seems to be working good now.   

Frank
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