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Post by husker on Jun 12, 2009 15:47:47 GMT -5
Guys,
My AM transmit is awesome! But the transmit on SSB is roughly 2-4 watts via Daiwa CN 101L meter. The book says the BM brd. Anyone know where to start to look on the BM brd for the issue? Everything else works very well and SSB USED to work well on this radio too. Any ideas on where to start?
I was wanting to do some DX today as the conditions are awesome in Nebraska!!
thanks guys!!
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Post by Marc on Jun 12, 2009 16:30:32 GMT -5
Husker
I had a similar prob till I replaced all the electrolytic caps in that board. You might start there.
Marc
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Post by husker on Jun 12, 2009 16:35:09 GMT -5
Hey Marc!! I see you PM'ed me, sorry I haven't gotten back to you..been working my butt off! I took today off for my birthday and figured I might as well play alittle! I already replaced them all, I am wondering if I have a cold joint or something....I have another brd I am going to slip in there to test in a bit. Conditions here in Nebraska are great right now!
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Post by Marc on Jun 12, 2009 16:36:35 GMT -5
No prob
check thr large one I also had a cold joint in that one Moonraker up yet??
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Post by husker on Jun 12, 2009 16:45:38 GMT -5
LOL..nope, but I have taken steel wool to it and cleaned and it is ready..jsut need time now!
Ok, I swapped out BMbrds, the problem is still there. I am starting to think maybe the ALC adj....
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Post by Marc on Jun 12, 2009 16:47:19 GMT -5
Could just reach back there and turn it up lol
R719 on watt mete /sw board
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Post by husker on Jun 12, 2009 17:29:03 GMT -5
I turned it 100% counter clock wise and it is MUCH better, but should it be at 100% counter clock wise?
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Post by Marc on Jun 12, 2009 17:49:13 GMT -5
No it should not.
Looks like a job for 2600!!!!
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Post by husker on Jun 12, 2009 19:17:38 GMT -5
OR Alan..I jsut wish I could do it myself  |
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Post by FIXR on Jun 12, 2009 21:17:54 GMT -5
Husker,
Marc has a good idea on replacing all of the electrolytic caps on the BM board. Cures most of the problems.
Fixr
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Post by husker on Jun 12, 2009 21:25:08 GMT -5
HI Alan, been looking for you tonight! DX is really rolling through here.
I tried a different brd from another Tram I have, same issue. So I turned R719 all the way counter clockwise..it's is working MUCH better, still not a full 12 watt peak..and I am thinking having R719 all the way over isn't too good of a thing either
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Post by 2600 on Jun 12, 2009 22:37:13 GMT -5
I know two reasonable ways to set the ALC pot. One requires a true peak-reading wattmeter. The "active" kind that only reads peaks with a battery or power cord. If you start the trimpot at the full-power end while modulating it with your voice, turn it until there is a sharp kick downwards on the meter reading. This point will probably sound okay. Never mind what the meter reads.
The other way is with a 'scope, preferably an envelope display. You'll see the flattened voice peaks this way, and you set the pot to a level just below where the peaks stop "flattopping".
Either that or just listen to it on another radio. Crank the pot downwards until the distortion goes away.
Depending on your wattmeter, the reading you get may be a bit disappointing. Most "passive" peak meters do not show impressive numbers on sideband. Seems that this kind of meter is marketed to AM operators, and how it behaves on SSB doesn't have much influence on how well they sell.
You'll find yourself having to choose between quality and quantity. The radio will always sound a lot smoother on SSB transmit if it's not pushing the final tube up against its peak-power limits.
73
P.S. Just change the five electrolytic caps on the balanced modulator board. You shouldn't even plug one into the radio with 30 year-old electrolytics on that pc board. They're cheap. They go bad. Deal with it!
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Post by husker on Jun 13, 2009 0:31:57 GMT -5
Caps have all been changed as of this evening.. I will test them in the morning
Thanks guys
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Post by Marc on Jun 13, 2009 11:09:59 GMT -5
Husker
Check the voltage on pin D18 3rd one back next to the filter
should be aprox 23MV with 1.5 Khz tone input at Mic.
Marc
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Post by Marc on Jun 17, 2009 12:35:01 GMT -5
Well how is that 201 coming along??
Marc
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Post by husker on Jun 20, 2009 12:29:26 GMT -5
Sorry Marc, I had to do a quick trip to Dallas this week. I am going to play some tonight and I will let you know
thanks
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Post by Marc on Jun 21, 2009 15:34:29 GMT -5
Big D sounds like fun.
Hope you have a nice Fathers Day!!!
Marc
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