In general, it would be ideal if there were zero voltage drop. This just
won't be the case in the real world. The VFO-B voltage indication is
reliable in terms of the voltage in receive vs. the voltage in
transmit. I think it reasonable to accept < 0.5 volt drop or less
between RX and TX at 100 watts output. Do consider the regulation of
the supply. Measure that with a good DVM at the supply terminals. And
here, it is reasonable to expect less than 0.1 volt change between RX
and TX at 100 watts. Many of the better supplies will be in the < 0.01
volt range under this condition.
If one finds more voltage drop than expected, then further investigation
is suggested. Are the terminals properly crimped and soldered on both
ends? Are the terminals tight fitting? Is the wire gauge correct for
the current demand and length? Are there other devices between the
supply and radio that will contribute to voltage drop? These are a few
questions to be answered.
Better regulation and maintaining a voltage at the radio between 13.5
and 14.5 will make for a cleaner transmitter in respect to transmitted
IMD. And that topic was "beat to death" in a previous discussion. If
the supply is not well regulated, be sure the voltage at the radio will
never exceed 15.0 volts.
73
Bob, K4TAX
On 11/5/2015 7:36 AM, ok1rp wrote:
Hi Jeff,
many thanks for your post regarding the soldering Anderson Plug leads
connections.
It seems that I should check it too as I have 0.7V drop RX/TX on VFO-B line
measurement.
(even although I never had any problem regarding the low voltage...)
It is good hint for my old timer K3 (#778) although it work like champ now.
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