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Author Topic: 813 Lew McCoy Linear Amp.  (Read 26041 times)
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W7SOE
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« Reply #50 on: May 23, 2015, 02:12:08 PM »

Gary,
   I am sorry to hear that you are opting out of this project but I certainly understand. I was looking forward to being partners in crime on this project. 😊

Rich
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Patrick J. / KD5OEI
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« Reply #51 on: May 23, 2015, 11:00:57 PM »

I too regret that you won't pursue it. I always enjoy seeing what others build and rebuild and the 813 is one of those good ol' big glass tubes that there seems plenty of and can take a little occasional abuse, a long-lived tube.
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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #52 on: May 24, 2015, 08:37:49 AM »

Correctly rated transformers/parts are easily/readily and cheaply available. Do you have a local ham mentor/friend in your area who can help you? Make the effort, have a backbone, be patient, if its all really worth it to you..maybe it isn't?...is it all about instant gratification? What a weird outcome with this.
C'est la vie.

Al VE3AJM
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Patrick J. / KD5OEI
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« Reply #53 on: May 25, 2015, 02:48:20 AM »

I sincerely hope you feel better some time and might consider building it, or something like that later. I understand about health, sometimes I don't feel well and not like working on stuff. I know what you mean about eyesight as well. I have to use glasses for this and take them off for that, it is very annoying. No pressure here 8-)

One last piece of encouragement I can offer, is that you can use one plate supply for more than one amplifier, and this can be done really cheap.

My friend uses one plate supply+modulator hooked to two amps, and he only lights up the filaments on the amp on the band he is going to use.

That way the amp chassis has plenty of room, no crowding. Plate supply is in the bottom of the rack. Could be under a desk just the same  but he has all racks.

One of the cheapest $ per watt transformers around is the old BC-610 plate transformer (Stancor P-9920). They are old and heavy and sometimes people will give them away for the shipping. You can choose 2500V@350mA or 2000V@500mA on that one with the flip of a primary voltage switch. A 10-20H choke an 6-12uF oil cap and you are good on that. With a capacitor input, 3500 or 3000V is possible at lower current.

I have gotten several big transformers for free or cheap because they are the old cast-iron-bell styles. Does not bother me and I have not had one blow yet even if they are 50 years old! I get a young helper to assist mounting them.
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Radio Candelstein - Flagship Station of the NRK Radio Network.
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