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Author Topic: Troubleshooting Collins 30L-1. Clean unit but way high swr reading  (Read 8181 times)
K7KBN
Member

Posts: 2802




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« Reply #30 on: July 21, 2013, 05:46:31 PM »

I believe there's a section in the manual covering alignment of the input circuitry.
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73
Pat K7KBN
CWO4 USNR Ret.
K0IZ
Member

Posts: 737




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« Reply #31 on: July 21, 2013, 06:14:38 PM »

RE 120 V, amp is small enough that 120 v operation should not be a problem, power load of under 15 amps.  Could be a problem on a specific circuit, however, if other substantial loads are also on that circuit.  In any case, your AC power choice is not causing your problem.

Since you have the problem on all bands except 10m, I think the chances of mistuned input circuits is low.  Maybe one or two bands, but not all (except 10).  And 10M might show low SWR due to some interaction of circuit, coax to amp, etc.  As mentioned by another poster, when amp is off or not keyed, transfer relay should be connecting amp input to amp output.  Best way to check is, as others have said, connect a dummy load to amp output and see what your radio shows for SWR (without using radio tuner).  Should be very low.  For this test you only need a 100w or even less dummy load.  If you radio can test at 20W or whatever, even smaller dummy load will do.

If doing this you have low SWR (should be on all bands), than at least you know the transfer relay NC (normally closed) contacts are ok, as well as the wiring to such.

Next, set the radio to zero power if you can, and key the amplifier.  You should hear the transfer relay close.  The relay is at the right rear of the amp.  If you don't hear a click, you might have a bad relay.

All in all, however, I tend to think you have either dirty relay contacts or dirty bandswitch contacts.
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K3VO
Member

Posts: 28




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« Reply #32 on: July 22, 2013, 11:43:10 PM »

1st. My 30L1 was the best amp I ever had. It likes 220v and the coax  does not have to be 20.5 feet. I used about 3 feet of coax and a Radio shack relay to key it  with a battery per the article by W6SAI.
2nd For  all you G5RV lovers . That ant was designed for old tube xmtrs with Pi Net works to match it. It s a good ant on 20 and a dummy load on others. Just put up a dipole as long as you can and feed it with open wire  feedline and a tuner with a 4 to 1 balun. Lew McCoy  my old friend W1ICP taught me that this was the best dipole. Look for a used Heath 2060 tuner which can handle a KW and use this between the amp and ant. W6SAI wrote many articles about the  poor performance of the G5RV.
If you buy a factory made ant you land up with the G5RV. Guys, its not hard to build a simple dipole. Thats what ham radio is about.
3 The odds that the  input has to be retuned is very low.  That is not your problem.  You need a real tuner at the end of th
at amp.
Good luck
K3Vo
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KE3WD
Member

Posts: 5689




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« Reply #33 on: July 23, 2013, 07:39:09 AM »

1st. My 30L1 was the best amp I ever had. It likes 220v and the coax  does not have to be 20.5 feet. I used about 3 feet of coax and a Radio shack relay to key it  with a battery per the article by W6SAI.
2nd For  all you G5RV lovers . That ant was designed for old tube xmtrs with Pi Net works to match it. It s a good ant on 20 and a dummy load on others. Just put up a dipole as long as you can and feed it with open wire  feedline and a tuner with a 4 to 1 balun. Lew McCoy  my old friend W1ICP taught me that this was the best dipole. Look for a used Heath 2060 tuner which can handle a KW and use this between the amp and ant. W6SAI wrote many articles about the  poor performance of the G5RV.
If you buy a factory made ant you land up with the G5RV. Guys, its not hard to build a simple dipole. Thats what ham radio is about.
3 The odds that the  input has to be retuned is very low.  That is not your problem.  You need a real tuner at the end of th
at amp.
Good luck
K3Vo

Absolutely agreed with this. 

While maybe not the finest amp I ever owned or used, the 30-L1, in my experience, performed yeoman's duty day in and day out in my shack for over two decades at least.  Even after obtaining full legal limit capability, the 30-L1 was often the first choice for breaking many a DX pileup.  CW mostly, as that is my mode of choice, but that 600W also worked well SSB and even for the occasional (horrors! say it isn't so!) foray into the AM, damn the tubes. 


73
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KD7KTV
Member

Posts: 8




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« Reply #34 on: August 08, 2013, 12:30:13 PM »

Thank you all for your comments.
I have an update.
While on vacation the ham who sold me the unit has been looking in to it.... The Collins.
The relay was fine.
He moved the band switch around and then 80 meters started showing power into the dummy load.
Then he looked closer.
The band switch has two sections; the one in front for input and the one in back for output.
Apparently the back one had slipped out of alignment by about 1/16 th of an inch.
He re aligned it and squirted some " special sauce" his words....in and all the bands started to put out 500 watts.
I asked him to do an air check this week..

More later.
Kd7ktv
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