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BC-614 Mods




 
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Author Topic: BC-614 Mods  (Read 4701 times)
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n9ami
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« Reply #25 on: December 20, 2020, 09:50:52 PM »

Not sure what I am doing yet. However I need to sort out how to properly key the thing using the 614.
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W2PFY
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« Reply #26 on: May 01, 2021, 11:29:28 AM »

Hello John, did you get this 610 on the air yet? I'll be back up and running this month at my amp. I forget where you are but perhaps we can meet up on 40 meters?

Regards,

Terry
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n9ami
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« Reply #27 on: May 01, 2021, 12:01:20 PM »

Oh 610 has been up and running nice.  Had to replace a 807 that went south so did both and discovered both parasitic resistors on those sockets were poof so repaired those. Who knows how long that's been like that or when the one 807 went did it take them out? Who knows.. but repaired and running nice.  The 614 is another story. I am back using my ranger for the speech amp for now.
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W2PFY
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« Reply #28 on: May 04, 2021, 03:27:38 PM »

Yes I too had an 807 problem. The glass on one 807 cracked and obviously air got in and that caused the circuit to draw too much screen current and took out the 22Kohm screen resistors. I replaced them with 1/2 watt resistors like was called for only to have them go south shortly thereafter. I then replaced them with (2) -1 watt resistors in parallel to get me close to the 22K I needed.

I often threatened that if resistors went bad again that I would install a rheostat in the screen circuit to vary the 807's output to the 250TH final tube. As it stands, if you have too much final grid drive, the only way to reduce that drive is to de-tune the exciter? I never tested the output for harmonics but they must be more prevalent when the only way to vary the drive is to de-tune it?

Anyhow, it's been about ten years and the screen circuit is still running strong?

Something to think about  Grin Grin 
 
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