On Tue, 7 Jan 2025, 15:42 Ron W4BIN, <ka4inm@gmail.com> wrote:
> On 1/7/25 3:28 AM, Lukasz wrote:
> > I'm thinking about adding these capacitors as 100nF or 10nF (depending
> > which one will fit) smd parts right between the base and emitter the
> pads.
> > Do you think that will work? If not, what would you do?
> >
> > 73,
> > Łukasz - SP4IT
>
> The trick is to make the input to the problem relays to require POWER to
> activate them. Feed a high current to those channels and drop the input
> resistor divider down to the hundreds of Ωs.
>
> Ron W4BIN
>
This will be difficult . I can pull at most 4mA at 3.3V on the control
lines out of the uC board. That is not a lot of power.... I'm already at
over half of that, so realistically ... I can't pull more than 3mA with a
bit of safety factor.
I think my problem may be a variation of the famous "pin 1" problem.
In my attempts to avoid ground loops I've not connected the shielding braid
on both ends to the case.
I just read you do that to avoid uV level hum on audio , not when a kilowat
of RF is flying past. So that's the first thing to change.
Then the coax that delivers +12V. The braid of that too is not terminated
on the chassis but goes inside. Despite having RF shorting cap to RF ground
right at case wall I think this may have to be replaced by a second coax.
Finally, if nothing helps at all I'll have to get rid of transistors and
replace them with transoptors. I wanted to avoid that, but it may be
required .
If anyone has one ideas please share.
73,
Łukasz - SP4IT (also SQ4KW)
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|