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Author Topic: GT550 on 10meters...  (Read 1974 times)
KA3IWU
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Posts: 20




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« on: March 27, 2012, 05:20:19 PM »

Just curious if anyone had suggestions for an old Galaxy GT-550.  I picked it up as a parts rig really cheap on ebay last year and it seemed like enough of it was together that I resurrected it and actually have it running fairly well.  Receiver works, and transmit works on all bands but 10m.  I am wondering if it is just that all the tubes are just really old now and won't work well at that frequency or if anyone had suggestions - there is drive, but on 10m it just seems unstable - instead of a "dip" for the plate, it will "peak" so I assume it is getting parasitics.  I rebuilt the parasitic suppressors, tried adjusting the neutralizing capacitor, tried a different set of finals, but the behavior stays the same.  I don't really need to use it on 10m, but it just bothers me that this one piece does not work.  I have the remote vfo, a homebrew calibrator, the vox, and correct power supply, so it is a nice complete station with the exception of 10m TX.  Funny that I paid under $50 for the main "parts" rig and just the other week someone paid over $400 for a bare 550 unit minus power supply or accessories untested because it was advertised as "mint" on ebay.

thanks for any suggestions,
Robert
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WD5GWY
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Posts: 392




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« Reply #1 on: April 01, 2012, 12:15:44 PM »

Not familiar with that particular radio. BUT, could it have been modded
sometime in the past for 11 meters? If so, that might explain the problem
you are having.
james
WD5GWY
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W4OP
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« Reply #2 on: April 03, 2012, 06:44:55 PM »

This sounds like a classic case of the PA needing neutralization. Did you follow the manuals on neutralization?

Dale W4OP
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KA3IWU
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« Reply #3 on: April 04, 2012, 04:46:03 PM »

Thanks for the replies.  I did make another attempt at neutralization and finally got it working a little better on 10 meters.  I probably need to go back through the whole thing to make sure the alignment is all good now that it seems about finished.  Nice to resurrect an old rig and get it usable.
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W4OP
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« Reply #4 on: April 04, 2012, 06:00:39 PM »

They are nice rigs. The electrolytics on the audio board that is attached to the rear wall seem to go bad and should be replaced- an easy job.

Dale W4OP
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