On my amp, the circuit locks out, lights a LED, and requires a manual reset. When I get some time I'll sketch out a circuit.
73 Tom W0IVJ Jerry Flanders wrote: > Sounds like a good workaround. Does it "lockout" somehow, or just buzz > until you manually shut it down? > > A circuit diagram would be helpful. Maybe it could be placed in the > knowledge base for reference. > > Jerry W4UK > > At 07:15 PM 7/18/2007, Tom Thompson wrote: > >> On my SDR-1000, I am using one of the open collector outputs to key >> the amp. If you AND a "good" ALC signal with that open collector >> output and use the ANDed output to key the amp, then your amp will >> only key when instructed to by the SDR AND the amp ALC not trying to >> shut things down. As soon as the amp ALC trys to shut things down, >> the SDR will no longer be able to key the amp. Granted this is not a >> gradual power fold back like ALC into the exciter gives you, but it >> should prevent the amp from keying under a bad SWR condition, and the >> SDR is capable of handling the high SWR condition until you get the >> problem fixed. >> >> Tom Thompson W0IVJ >> >> Jerry Flanders wrote: >> >>> Agreed that the circuit is trivial, but the interface between that >>> circuit and PowerSDR or SDR-1000 is not. >>> >>> Only thing I have been able to think of is an independent attenuator >>> pad between exciter and amp that would be switched in under ALC >>> "panic control" voltage level. If anyone has a better idea, please >>> speak up. >>> >>> Jerry W4UK >>> >>> At 05:58 PM 7/18/2007, Tom Thompson wrote: >>> >>>> Jerry, >>>> >>>> The exciter does not cut back the drive in my set up. What happens >>>> is the amplifier refuses to key under a fault condition, so it is >>>> bypassed and the exciter sees the antenna instead of the amp input. >>>> >>>> In thinking about this, it might be pretty easy to detect the ALC >>>> out of the amp and use it to tell the SDR not to key the amp. You >>>> would have to set a threshold such that only shut down ALC would do >>>> this, but the circuit would be trivial. >>>> >>>> Tom W0IVJ >>>> >>>> Jerry Flanders wrote: >>>> >>>>> Hi Tom >>>>> >>>>> How does your exciter "know" to cut back the drive? In most >>>>> exciters, the hardware ALC does this, and the amp can use that to >>>>> command a cutback. But if the exciter has no hardware ALC (like >>>>> Flex-radio products), then what? >>>>> >>>>> Incidentally, all the non-Flex exciters that I am personally >>>>> familiar with have hardware ALC. >>>>> >>>>> Jerry W4UK >>>>> >>>>> At 05:21 PM 7/18/2007, Tom Thompson wrote: >>>>> >>>>>> In the homebrew , 600 watt amplifier that I built, I placed the SWR >>>>>> bridge before the filters so the amplifier will fault if the >>>>>> antenna is >>>>>> wrong or the bandswitch is wrong. The fault mode just does not >>>>>> allow >>>>>> the amplifier to be in line. If it is a high SWR that causes the >>>>>> fault, >>>>>> then the exciter cuts back the power after the amplifier faults and >>>>>> takes itself out of the line. My amplifier also faults with over >>>>>> drive >>>>>> and over temperature. It really should be the amplifier that >>>>>> handles >>>>>> these conditions, so that the amplifier can be used with a >>>>>> variety of >>>>>> exciters. >>>>>> >>>>>> Tom Thompson W0IVJ >>>>>> >>>>>> Robert McGwier wrote: >>>>>> >>>>>> >FireBrick wrote: >>>>>> > >>>>>> > >>>>>> >>Maybe I don't understand but... >>>>>> >>In the Quadra, ALC is also used to cut back ft1000mp power in >>>>>> case of >>>>>> >>wrong antenna selection. >>>>>> >>The high swr, would cause the Quadra ALC to shut down exciter >>>>>> power to >>>>>> >>protect the Quadra finals. >>>>>> >>Especially in dxing or contesting, it's so easy to select the >>>>>> wrong >>>>>> >>antenna. >>>>>> >>And, as you move around in a band the swr varies slightly. >>>>>> >>In my case, the 80 dipole it can vary greatly. >>>>>> >> >>>>>> >>Maybe I need to understand how the ALC in the Flex works to >>>>>> prevent a >>>>>> >>higher swr from overloading the Quadra. >>>>>> >>I know that a high swr/high drive situation will trip out the >>>>>> Quadra. >>>>>> >> >>>>>> >> >>>>>> > >>>>>> >Now that is something I had not considered. There is not a >>>>>> feedback >>>>>> >mechanism that would allow us to know the Quadra saw a crappy >>>>>> load. In >>>>>> >this case, it would see the 50 Ohm input of the Quadra input >>>>>> circuit and >>>>>> >be happy to rock right along at full power. That is a valid input. >>>>>> Who >>>>>> >has not contested and hooked up the wrong antenna? >>>>>> > >>>>>> > >>>>>> > >>>>>> >>when I had my MP/Quadra combo, if I errored and my 80 tuner was >>>>>> set for >>>>>> >>cw and I was in ssb, the ALC from Quadra backed down the MP >>>>>> before it >>>>>> >>could trip out. >>>>>> >> >>>>>> >> >>>>>> >> >>>>>> > >>>>>> >Bob >>>>>> > >>>>>> > >>>>>> > >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> FlexRadio mailing list >>>>>> FlexRadio@flex-radio.biz >>>>>> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >>>>>> Archive Link: >>>>>> http://www.mail-archive.com/flexradio%40flex-radio.biz/ >>>>>> FlexRadio Knowledge Base: http://kb.flex-radio.com/ >>>>>> FlexRadio Homepage: http://www.flex-radio.com/ >>>>> >>>>> >>>>> >>>>> >>> >>> > > > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
