[BULK] - [Amps] Info on Mirage 6M 10/150 Amp?

[Steve Katz]

	I surely agree with Rich's comments, below.  RF-activated T-R
switching, especially in amplifiers using two or three relatively slow
relays as the Mirage amps do, is very much not great.  However, at least
they do provide for variable drop-out delay (similar to VOX), and if you set
this long enough, you don't go through the relays' entire life cycles in a
couple of months as you would if the delay is set too fast.

	It should also be noted that a lot of these VHF amps have built-in
RX preamps using sensitive devices (MOSFETs, GaAsFETs) that can't take
transients worth a darn.  When using RF-actuated T-R switching, these
devices are far more likely to fail than if conventional
transmitter-controlled "hard keying" is used.

	Of course, a GaAsFET preamp on 50 MHz is kind of silly, anyway....

	-WB2WIK/6

> **  Joe -- RF controlled bias-switching works well on AM and FM.  This is 
> not the case for SSB and CW.  For those two modes, transceiver-control 
> works best.
> 
> >Rick, I would be operating exclusively CW and SSB.
> >
> >73, Joe
> >
> >R.Measures wrote:
> >
> >>**  What mode are you using on 6m?
> >>
> >>  
> >>
> >>>Joe,
> >>>
> >>>In many Mirage 6m amps, including a model A1015 that I have at home,
> the
> >>>circuitry for RF sensing is actually mostly in place, on the circuit
> board;
> >>>it's just not connected!  This makes it reasonably easy for anyone with
> a
> >>>screwdriver, soldering iron and about ten minutes to modify for RF
> sensing
> >>>if they wish.
> >>>
> >>>In the case of my A1015 (about 3 years old), the entire circuit was in
> place
> >>>except for the coupling capacitor that drives it.  Took me about five
> >>>seconds to find that omission, and add the cap from my own stock...
> >>>
> >>>73 de Steve WB2WIK/6
> >>>
> >>>"Success is the ability to go from failure to failure with no loss of
> >>>enthusiasm." -Winston Churchill
> >>>
> >>>    
> >>>
> >>>>-----Original Message-----
> >>>>From:	Joe Giacobello [SMTP:k2xx at swva.net]
> >>>>Sent:	Monday, February 16, 2004 11:35 AM
> >>>>To:	Steve Katz
> >>>>Subject:	Re: [BULK] - [Amps] Info on Mirage 6M 10/150 Amp?
> >>>>
> >>>>Tnx for your help, Steve.  I appreciate it.  I knew absolutely nothing
> >>>>about the new regs and thought someone had sold me a faulty rig.
> >>>>
> >>>>73, Joe
> >>>>
> >>>>Steve Katz wrote:
> >>>>
> >>>>
> >>>>	Hi Joe,
> >>>>	
> >>>>	Yes, the 6m amplifier *is* different.  There's an FCC rule that
> >>>>prohibits
> >>>>	RF-sensed amplifiers from being sold in this part of the spectrum.
> >>>>	
> >>>>	However, it is perfectly acceptable for an amateur to modify
> >>>>equipment in
> >>>>	this regard, for his own use.
> >>>>	
> >>>>	WB2WIK/6
> >>>>	
> >>>>	"Success is the ability to go from failure to failure with no loss
> >>>>of
> >>>>	enthusiasm." -Winston Churchill
> >>>>	
> >>>>	  
> >>>>
> >>>>		-----Original Message-----
> >>>>		From:	Joe Giacobello [ SMTP:k2xx at swva.net
> >>>><mailto:SMTP:k2xx at swva.net>]
> >>>>		Sent:	Sunday, February 15, 2004 6:34 PM
> >>>>		To:	Amps
> >>>>		Subject:	[BULK] - [Amps] Info on Mirage 6M 10/150
> >>>>Amp?
> >>>>		
> >>>>		I recently had a Mirage 10W in, 150W out 6M brick amp in the
> >>>>shack.  
> >>>>		When I checked it out, it wasn't working.  It seemed that
> >>>>the RF from 
> >>>>		the exciter was feeding straight through to the output.  I
> >>>>assumed that 
> >>>>		the RF sensing antenna relay changeover circuitry was not
> >>>>working.  
> >>>>		However, I've since been told that the 6M amps have to be
> >>>>keyed from the 
> >>>>		exciter by grounding through the RCA jack on the rear and do
> >>>>not work by 
> >>>>		RF sensing.  My 2M and 440 MHz Mirage amps go to transmit by
> >>>>RF sensing 
> >>>>		or via the RCA jack.  Is the 6M unit different?  I'd
> >>>>appreciate any 
> >>>>		information on the issue.
> >>>>		
> >>>>		73, Joe
> >>>>		
> >>>>		_______________________________________________
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> >>>>		    
> >>>>
> >>>>
> >>>>
> >>>>	  
> >>>>
> >>>>      
> >>>>
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> >>>
> >>>    
> >>>
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> >>
> >>  
> >>
> >