Older carbon resistors are often found to be too high in value. The
simplest answer is to get a HV probe for your DVM and calibrate the
meter in the amplifier.
73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 28/12/2022 17:51, Steve London wrote:
First, thanks for the suggestion/schematics for low voltage PTT. I have
that working now.
Seems like the HV on my PT-2500A might be low. The meter shows only 2700
volts in standby. But how do I know that is telling the truth ? The circuit
is straightforward - A voltage divider consisting of 1 megaohm and 10K
going between + and - on a filter cap. The 10K is a pot to calibrate the HV
meter. Could be that the HV is okay, but the calibrate pot needs tweaking ?
It's also interesting that the 1 megaohm is tapped off the first of 5
filter capacitors. That makes the assumption that the voltage drop across
each capacitor/bleeder resistor is equal.
To make some measurements, I am thinking of putting 12 volts on the
transformer primary and see what the B+ looks like. Yes, there's still some
pretty high voltages, but it seems a lot safer than trying to measure 3 KV
directly. Any other suggestions ?
Anyone know what the secondary voltage of the HV transformer is supposed to
be ?
Thanks and 73,
Steve, N2IC
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