>Jim,
>
>I commend you for what you are doing for a nice HB amplifier. I have a
>couple suggestions.
>
>I wind my own plate RF and filament chokes. For the plate RF choke I use
>fiberglass tubing available from Alan Bond for next to nothing and get # 24
>wire from a local electric motor shop. Before I got a small lathe I would
>use an electric drill with a piece of 1/4 shaft in it and some rubber feet
>on each end of the tubing to hold it and rotate the tubing and wind the wire
>on it.
? Sounds good., Terry. And always check the choke for resonance locations
with a dipmeter with the choke wired in place, unshorted, lest one fire up the
choke (literally) when ''firing up''.
>For the filament chokes I have used both straight 8 inch rods and
>torroid cores and I wind two # 10 wires (also obtained from the electric
>motor shop) to form a bifilar choke.
>
>If you are wanting to use the Z-50 choke in the HV lead after the big RF
>choke you can wind a smaller choke from the same # 24 wire to fill that
>need.
>
>Good Luck,
>Terry W6RU
>
>----- Original Message -----
>From: "Jim Isbell" <millenniumfalcon@cableone.net>
>To: "Mail list for Amplifiers" <amps@contesting.com>
>Sent: Wednesday, May 21, 2003 8:31 AM
>Subject: [Amps] A new hombrew from old parts
>
>
>> Where I am:
>>
>> I am just about through collecting parts for my "new" 4-1000A linear.
>> All the parts have been collected from various "junk boxes" and have
>> been previously used...except the tube itself which is new.
>>
>> What I am doing:
>>
>> I will be building a "new" amp from parts that were not originally
>> designed particularly to be used together so there will be differences
>> in the values and I will have to tweak it all into compliance. I am
>> using the schematic from the Eimac publication AS-10 "Zero Bias Triode
>> Operation in a 1-Kw Linear" by Larry Kleber, K9LKA as my starting point
>> and then tweaking it as need be to make it work with the components I
>> have on hand. One major change will be the input tank that in the
>> schematic has a variable capacitor and switched inductor where the tank
>> circuit I have on hand has 5 separate coils with caps across and tuned
>> by slugs.
>>
>> What I have:
>>
>> I have an antenna capacitor ( Johnson 153-30) a plate capacitor (Johnson
>> 154-15 20-145) a Pi coil (Air Dux PI #195-2) as well as the Eimac
>> socket, chimney, anode cooler and tube. I also received a bypassed
>> plate choke and a pair of door knob caps. Most of the components were
>> previously used with a pair of 3-500s in a Kilowatt amp so should suit
>> the 4-1000 satisfactorily. I am not sure about the suitability of the
>> plate choke, but the description of the plate choke in the article is
>> very close to what I have. I dont have a grid dipper so all inductance
>> will have to be calculated from coil dimensions rather than "dipped".
>> So I am looking for a good formula that will do that calculation for
>> round as well as flat conductors.
>>
>> What I need:
>>
>> The pieces I still need are the HV power supply (transformer, rectifier,
>> and various components), about a dozen .01x1000v ceramic disk caps, a
>> few RF chokes (B&W 800, Ohmite Z-50, B&W FC30A), four meters, and I need
>> a chassis/enclosure. For a chassis enclosure I would like to find
>> something that would look good with a Collins S-Line.
>>
>> I would also like to find at least one other schematic so if I decide
>> this one is not the best I have some choices.
>>
>> I would like to know if there is a good description of the initial
>> tuning of a "one off" amp since I am sure it will not work right off the
>> dock and I will probably have to do some design changes and
>> modifications to get it going. This is my first amp project and I will
>> need to know how I can tell if it is working or not working properly and
>> some hints on things to try/check/fix when it isn't. Hopefully someone
>> has written up a generic article on "home-brew" amp tuning.
>>
>> Any help that anyone can offer even just moral support would be
>appreciated.
>>
>> Jim W5JAI, near Corpus Christi TX
>>
>> _______________________________________________
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>>
>
>
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Rich, AG6K, 805-386-3734, www.vcnet.com/measures
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