Mosfet Box. KL 703. Question may apply to all boxes. In AM, relay stays locks in with carrier. Using SSB Switch locks the relay in for SSB use. So is there any harm in just leaving the switch in the SSB position for AM operation as well?
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Any Harm to Leaving Mode Switch in SSB All The Time?
- Thread starter Wire Weasel
- Start date
It will have a slight delay before releasing to RX if left in SSB mode, but no other affect.
You just won’t be able to “get down” fast enough!!! LOL
The switchover delay, but also, any inadvertent RF pokes from the radio - can also spike the amp - and with the SSB mode in, the SSB mode itself on those amps is making the Gates biased a little higher to make them more sensitive to Low-level input signal (your dynamics of SSB).
May make the amp run harder than it should.
So if you can avoid leaving SSB on all the time - or at least remember to switch it off for long-term AM/FM use - your Gates will thank you.
May make the amp run harder than it should.
So if you can avoid leaving SSB on all the time - or at least remember to switch it off for long-term AM/FM use - your Gates will thank you.
If any of you have time, do up a search for RM Italy and Handy Andy here at the site - you'll see several strings of posts regarding the various amps.
So to help clarify.
The BIAS I'm referring to, is when the amp is keyed in SSB mode - there is a boost to the Gate voltage applied (pull up) so the Amp can swing linearly and not get too crunchy.
In AM (FM) Modes there is enough of a signal to rectify and add voltage from the RF and it's carrier - to help the AMP stay keyed and not interfere with the envelope of the signal - so it follows pretty closely as if Class C can follow as allowed.
But then too, when your amp is in SSB mode, you HAVE to be careful with swing in your carrier - you can blow the amp from the power swings.
It's why ALC and AMC - and in a Galaxy AVC, are used to control and tame the dynamic signal swings audio is - so to place limits helps with "punch" but too much and you're sounding pinched and compressed.
So it's why I suggest that it is "ok" if you run your amp in SSB mode, just don't go doing "quik-key" or other efforts of spiking the input to the amp in SSB mode - just to keep the relay keyed up - it can generate a spike-artifact by itself at a much different frequency you are not aware of, that your antenna and system may see as an SWR spike and if allowed - damage the amp - by blowing up the MOSFETs' in random fashion as it sees fit.
This is the danger of the SSB delay in radios that have their own 52-MHz traps, but if they have scratchy or noisy keyups' those spikes and the amps own response to "quench" - to stop or shut down so you can hear, can cause a ringing effect at a lower frequency - a blip or even a squawk - that if the antenna is not tuned to that resonate frequency - will reflect the energy back into that amp as a feedback squeal or loop causing the amp to find various ways to dissipate the energy it sees - and that is with that delay in the relay unkeying.
It's Zener protected - but does not prevent the broad-band effects of SWR reflection from occurring - just tries to protect the Gates - but not from itself.
So to help clarify.
The BIAS I'm referring to, is when the amp is keyed in SSB mode - there is a boost to the Gate voltage applied (pull up) so the Amp can swing linearly and not get too crunchy.
In AM (FM) Modes there is enough of a signal to rectify and add voltage from the RF and it's carrier - to help the AMP stay keyed and not interfere with the envelope of the signal - so it follows pretty closely as if Class C can follow as allowed.
But then too, when your amp is in SSB mode, you HAVE to be careful with swing in your carrier - you can blow the amp from the power swings.
It's why ALC and AMC - and in a Galaxy AVC, are used to control and tame the dynamic signal swings audio is - so to place limits helps with "punch" but too much and you're sounding pinched and compressed.
So it's why I suggest that it is "ok" if you run your amp in SSB mode, just don't go doing "quik-key" or other efforts of spiking the input to the amp in SSB mode - just to keep the relay keyed up - it can generate a spike-artifact by itself at a much different frequency you are not aware of, that your antenna and system may see as an SWR spike and if allowed - damage the amp - by blowing up the MOSFETs' in random fashion as it sees fit.
This is the danger of the SSB delay in radios that have their own 52-MHz traps, but if they have scratchy or noisy keyups' those spikes and the amps own response to "quench" - to stop or shut down so you can hear, can cause a ringing effect at a lower frequency - a blip or even a squawk - that if the antenna is not tuned to that resonate frequency - will reflect the energy back into that amp as a feedback squeal or loop causing the amp to find various ways to dissipate the energy it sees - and that is with that delay in the relay unkeying.
It's Zener protected - but does not prevent the broad-band effects of SWR reflection from occurring - just tries to protect the Gates - but not from itself.