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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