[HBR] Home Brew

[David Newman]

Ian,


Not sure what you are asking.   Right click the photos, download, and 
look  at them on your photo browser.  Much detail can be seen.


On the amplifiers, I started with the one kilowatt amplifiers that were 
in ARRL handbooks in most of the 1960s.   But I made one change.  The 
ARRL amplifiers use a Pi network at 813s tube output.  I changed to a 
Pi-L network. You can look up these networks in more recent ARRL 
handbooks.  They give good detail for designing.  I.e., a lot of 
computer design was put in to charts, tables, etc. which was not 
available as readily in the 1960s.


Second, the 1960s amplifiers in ARRL handbook only were made for 80, 40, 
20, 15 and 10 meter bands.  All used two 813s in output. 



I added a 160 meter amplifier using four 813s and of course, my Pi-L 
NETWORK.   Thus, I started with the ARRL handbook, but modified and 
added.  Note that the Pi network in output (connects between plates of 
813s and antenna) has about 35 dB suppression of side lobes, i.e., 
harmonics.     Keep in mind, class C amplifier can generate a lot of 
harmonics.  In the older days, the technical requirements were not as 
stringent as today.  The Pi-L network between the plates of the 813s and 
antenna can have approximately 50 dB suppression.   Much better than Pi 
network.


I liked the ARRL modular design, per band.  This allows optimum design 
of each amplifier.  And  it allowed me to modify and experiment. 


I suggest the 1964 ARRL handbook, but I know they are in several years 
of the handbook.  



Also, in the 1960s, FCC power requirements were based on input power to 
final amplifier(s).  Thus, one kilowatt is input power.  Today, all is 
based on output power.


The 160 meter kilowatt amplifier uses four 813s.  I conceivably could 
run it at 2 kW input power.   I don't run it at 2 kW, except into a 
dummy load.   I was curious if I could do it.  I still am experimenting.


Also, all of these were made before 2000.  I was passenger in a horrific 
auto crash in April 2001, in Russia, and have not done much since.  I 
still thought these photos would be interesting.


I liked the layout of the front panels of the amplifiers in the ARRL 
handbook.  So I copied.  All metal work was done with electric hand 
drill, saber saw, and a lot of filing for the rectangular vent windows.  
I do not have any fancy shop equipment.   The chassis are all home made 
from sheet metal.



I hope this helps.


73s,


David
W3HYM





Ian Wilson wrote:
> Very nice, David; is there more detail on what the photos are
> somewhere (sorry if I overlooked something).
>
> 73, ian K3IMW
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