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kc2ifr
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« on: June 20, 2009, 11:31:32 PM » |
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This is my much modified Johnson 500.
Notice the BIG HV plate transformer.......
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Steve - WB3HUZ
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« Reply #1 on: June 21, 2009, 12:46:26 AM » |
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Nice! What's the top photo, external audio?
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W2NBC
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« Reply #2 on: June 21, 2009, 01:26:02 AM » |
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I have Johnson Envy, Mr. Bill.. But that first pic looks like a cathode follower.. right??
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N3DRB The Derb
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« Reply #3 on: June 21, 2009, 03:28:36 AM » |
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thats a BIG JOHNSON you got there......
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W2PFY
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« Reply #4 on: June 21, 2009, 08:35:17 AM » |
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May I play with your Johnson???
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The secrecy of my job prevents me from knowing what I am doing.
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kc2ifr
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« Reply #5 on: June 21, 2009, 10:56:30 AM » |
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Sorry Steve,
I should have said what that is.
Its the cathode followers that drive the 572b's.
Currently its using a pair of EL34's but was designed for 5881's etc.
Didnt realize how dusty it is untill I took the pics!
Bill
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Steve - WB3HUZ
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« Reply #6 on: June 21, 2009, 11:59:26 AM » |
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TNX. Very nice.
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Todd, KA1KAQ
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« Reply #7 on: June 23, 2009, 06:21:46 PM » |
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And you should never have any of the typical PS issues by the looks, Bill. The 500 strikes me as Johnson's best transmitter, though price probably meant that more Rangers sold.
Thanks for sharing the pics.
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known as The Voice of Vermont in a previous life
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W1AEX
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« Reply #8 on: June 23, 2009, 07:43:04 PM » |
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The Johnson 600 sounded very nice on 75 meters last night Bill. Very clean audio from that rig!
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One thing I'm certain of is that there is too much certainty in the world.
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N3DRB The Derb
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« Reply #9 on: June 23, 2009, 07:44:50 PM » |
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oh, and I MUST say your tube cooling system is engineered to the extreme.
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kc2ifr
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« Reply #10 on: June 24, 2009, 04:52:08 PM » |
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TNX for the kind comments guys..... Derb.......it took me a long time to mount that damn fan.  |
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KB2WIG
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« Reply #11 on: June 24, 2009, 10:46:20 PM » |
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"" Derb.......it took me a long time to mount that damn fan. " Isn't that painful?  klc |
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What? Me worry?
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K5UJ
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« Reply #12 on: June 24, 2009, 11:11:18 PM » |
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Hey, I've been meaning to say I like that plate transformer and supply. I got some ideas looking at that p.s. I'm getting together the parts for a plate supply for my amp to improve on the present situation with the stock wimpy low duty cycle supply. I need to build the rectifier now; then I'll be ready to work on the cabinet. It may take a few months but when I'm done, the amp should be able to put out 250 to 350 w. (depending on % pos. modulation) carrier all day. It'll weigh almost twice what the entire stock amp weighs. So, I enjoyed looking at what u doing with the Johnson.
73
rob k5uj
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"Not taking crap or giving it is a pretty good lifestyle."--Frank
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flintstone mop
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« Reply #13 on: June 25, 2009, 09:26:54 AM » |
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I gotta get my radio lit back up to hear this radio of yours, Bill. Too much honey-do stuff and keeping up with the grass cuttin.
The plate transformer looks like a Peter Dahl unit.
Fred
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Fred KC4MOP
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kc2ifr
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« Reply #14 on: June 25, 2009, 02:54:27 PM » |
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Fred,
Yup...its a Peter Dahl, probably one of the last he made before selling out. Its the outboard version. He made 3 of 4 different ones for the 500. This one is made to be mounted outside the power supply. I could never get the top on the power supply with this transformer. The tranny is rated for 800 mills instead of the 500 mills of the original and the high voltage is about 300 volts higher with it.
The mod transformer is also a Peter Dahl but its built to original Johnson specs so not much gain there as far as performance.
Bill
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Todd, KA1KAQ
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« Reply #15 on: June 25, 2009, 06:53:21 PM » |
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Curious Bill - was this the same Johnson you were using when I was in Randolph? If so, it sounded nice, and you were the only other station besides G who could slap the Guess meter full right and make it beg for mercy. Granted, you were just on the other side of the mountain range, but still...
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known as The Voice of Vermont in a previous life
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kc2ifr
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« Reply #16 on: June 26, 2009, 11:40:21 AM » |
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Todd,
It is the same radio but it was not the configuration u see now. At that time I was driving the modulators with a transformer and it had its original plate transformer.
Bill
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