One more thought. Is the aircon on the same power phase as the maser? Are you split phase in the facility at least.
On Fri, Jun 3, 2016 at 9:24 AM, paul swed <[email protected]> wrote: > Jim, > My head is precisely in the get it away from the unit approach. > Did not mention it for the following reason. > Its well understood and for time-nut boring. Its more fun to figure out > peak currents and such. > But I tend to fall into the get it done camp and move on. > That doesn't mean its a simple answer. Flex duct is bad. So only use it in > the last few feet. You want low resistance hard duct. > Then the fun of the return feed. Often overlooked and poorly considered. > Regards > Paul > WB8TSL > > On Fri, Jun 3, 2016 at 1:00 AM, Jim Palfreyman <[email protected]> wrote: > >> Hi All, >> >> Thanks so much for your input and thoughts. It has really proved helpful >> here at the observatory. >> >> As it turned out we easily obtained a zero-crossing solid state relay so >> we >> thought we'd try it. >> >> And, drumroll...... >> >> >> >> It made things so much terribly *worse* than ever before. (As predicted by >> many of you above.) >> >> We are going to try a SSR that switches at the peak - but we need to order >> one. So stay tuned on those results. >> >> There is of course the "move the bloody thing far away from the maser" >> solution which could end up being a serious option. These air conditioning >> units are small and cheap (window-type), so we are trying to find the >> cheapest solution - and if that ends up being some ducting - so be it! >> >> >> Jim Palfreyman >> >> >> >> On 26 May 2016 at 13:13, Andy <[email protected]> wrote: >> >> > On Wed, May 25, 2016 at 12:59 PM, Mike Monett < >> [email protected] >> > > >> > wrote: >> > >> > LTspice shows switching at 0V is the best point in time. ... >> > >> > >> > >> > Bzzzt! Your simulation is seriously flawed, and your conclusions are >> > wrong. What you forgot, or may not have realized, is that SPICE's >> initial >> > transient solution is obtained by having the signal sources already >> turned >> > on (at the moment of the Big Bang) and set to their initial value, so >> the >> > current through L2 is limited by DC conditions. That is not anything >> close >> > to switching the driving voltages on. It is having one waveform sit at >> > +169.7V DC for a very long time ('forever'), and then letting it follow >> a >> > cosine wave. >> > >> > Re-run the simulation with "UIC" added to the .tran statement (.tran >> 50ms >> > uic) and see what it shows. Using UIC forces the initial voltage to be >> 0V >> > at time=0, the start of the simulation. That's like having the switch >> > initially open. >> > >> > Or if you don't like that, multiply the sources by a PWL waveform that >> > starts both voltages at 0V and then switches them on, a few milliseconds >> > into the simulation, with the appropriate phase. >> > >> > Or use an actual switch. LTspice has a switch element you could use. >> > >> > I guarantee you, the case with the voltage switching on at the 0V point >> in >> > the voltage waveform, causes greater currents. >> > >> > The smaller surge current happens when the source is connected at the >> > moment when the current i(t) would be 0A if it were a continuous >> waveform. >> > For an inductive load, this happens when the voltage v(t) would be +/- >> peak >> > (or near peak, for a real load which has both inductance and a little >> > resistance). This condition also results in no surge, thus no L/R >> decay. >> > >> > All of this might not be relevant to a mechanical system, where surge >> > current is caused by rotational inertia, rather than anything >> electrical. >> > >> > Regards, >> > Andy >> > _______________________________________________ >> > time-nuts mailing list -- [email protected] >> > To unsubscribe, go to >> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> > and follow the instructions there. >> > >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
