As more zero voltage crossing SSRs are installed to power ON these radios, it will be interesting to see if there is an increase in power transformer failures due to corona discharge (aka wire insulation failure) in the? high voltage winding of these hallicrafters radios.??
Zero voltage crossover is at the instant where current in the transformer winding is at a maximum.? Inductive circuits want to maintain a constant current flow through a winding so the collapsing magnet flux at turn OFF will generate as high a voltage as is possible so as to maintain this current flow.? This is the nature of inductive circuits.??
I do not know what the exact failure mechanism is when switching from ON to STANDBY to OFF to STANDBY to ON in rapid succession.? But evidently it is the worst possible condition which generates a voltage high enough to cause the wire insulation to fail.? Not understanding this failure mechanism means to me that any proposed solution is just a shot in the dark.? Perhaps this point was understood by the HT-37 design team and that a workable solution was either just too costly or perhaps not even available?
Regards,
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Saturday, July 13, 2024 at 10:51:13 PM CDT, Rick W4XA <myr748@...> wrote:
On Sat, Jul 13, 2024 at 06:09 PM, =R= wrote:
?
What is problematic for the transformer is turning the radio from ¡°on¡± to ¡°standby¡± to ¡°off¡° and then immediately back to ¡°on¡±.?
?
The manual cautions against this.
73,
?
=Randy=
WB6MAI?
?
=R=
Randy,
I have to apologize for taking the discussion away from this and I have to say I have the same question too!
The "Caution " (page-6) is to momentarily pause in STBY before turning it off.
Is there another caution to not immediately turn it back on?
I looked at the HT37 schematic (and my HT32B) but because I don't have a full schematic, I was unable to determine what exactly would happen by turning the thing directly off without pausing in STBY. The HT32B doesn't appear to have have that caution. ? -- 73/Rick W4XA __________________________________ All posts are created using OpenSuSE Leap 15.5 x64 Linux
Jim Whartenby