[AMPS] Amp. Bypass SWR
Sun, 07 Nov 1999 18:32:48 -0500
Hello Amp. Fans
Should the amp. bypass circuit introduce a SWR reading of around 1.3 to 1
at 14 MHz. when a 50 Ohm dummy load is connected to the output of the amp.
and a SWR analyzer connected to the amp's input?
The homemade amp. has a RB2A Jennings DPDT vacuum relay for switching the
input and output. A 4 inch run of 1/2 inch wide copper flashing is run
from the ouput pole of the RB2 to the center pin of the output coax
connector (SO 239). A couple inch length of 3/8 inch braid is used between
the normally closed terminals, A 10 inch length of RG 58 is run from the
other RB2 pole to a BNC chassis connector (the shield is connected to the
chassis at one end).
A Heathkit Cantenna and a MFJ SWR Analyzer are used. The RG 58 cables have
a 1 to 1 reading when used to connect the MFJ directly to the Cantenna.
As you go higher in freq. looking at the Cantenna through the amp. bypass
arrangement, the SWR increases and vice versa when decreasing freq. from 14
Are these type of readings normal, should they be lower - closer to 1 to 1,
is this an indication of a bad component in the bypass circuit?
Hope this is sufficient explaination of what is in the amp and how it is
connected? Any information will be appreciated as have to do a bit of
rework in the amp. Now is a good time to do the investigation and repair
to the bypass if needed.
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