Kelvin:

Thanks for these very helpful instructions.

I will give them a try when I get some uninterrupted time to do so.

Again, this is much appreciated.

Tom Behler: KB8TYJ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Kelvin Marsh
Sent: Tuesday, March 11, 2014 8:13 AM
To: [log in to unmask]
Subject: Adjusting drive power for amps

Hi Tom,

I guess I'm replying to your response to Steve, about the tripping relays
<smile>.  You mentioned cutting back the exciter power to the amp, but here
is how it's recommended to set the power for the solid state amp I use, and
it seems sensible.

You actually set the ALC for the amp in a similar way, but as you do not use
ALC, I won't go into that here.  I'll also add that the following steps are
only for amps where the power from the radio will not exceed the amp's
maximum drive rating.  If your radio can exceed the amp's drive rating, then
in my opinion, it is very unwise to not use ALC.

BTW, to clarify, the amplifier ALC used to fold back the radio's power to
the amp, is not the same as the ALC you adjust on the radio for voice
transmissions.

Here are the steps for setting the drive power:

Firstly, turn off the amp, and set your transceiver to maximum power, say
100 watts.

Next, Record the actual output power the rig is putting out on every band,
and make a note of which antenna and band shows the highest power.  You'll
need to tune up with the external ATU on every band in the normal way.
Personally, my dipole on 80m always shows the highest output, and 12m on the
beam the lowest output power.

Next, switch back to the band and antenna with the highest noted power
output.

Next, turn the radio's power down to minimum.

Next, turn on the amp and increase the drive power until you get the rated
power from the amp .  (Note, if there is any chance your radio can exceed
the amp's maximum expected drive power, you can damage the amp if the amp
never reaches the expected output, and you keep increasing the drive.)

Next, again turn off the amp or put it into bypass.

Next, record the radio's drive power.  Say it's 35 watts.

Now, whenever you use the amp, never exceed 35 watts from the radio
regardless of the band.  You may not get full power on certain bands, but
you'll never be needlessly over driving either.

Best wishes, Kelvin Marsh - M0AID

Working to improve accessibility for radio amateurs with disabilities

www.active-elements.org

For accessibility evaluations of amateur equipment and MP3 manuals


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Tom Behler
Sent: 10 March 2014 23:43
To: [log in to unmask]
Subject: Re: Need To Find A Replacement Radio

Steve:

Well, I'm not an expert on these things, but I believe it is the T/R relays
that are tripping.

They don't trip often, but do so on occasion, and I haven't figured out a
consistent pattern to it yet.

My theory is that I'm either over-driving the amp at times (which is why I
have now cut the input power back a bit), or perhaps I'm getting RF back
into the amp somehow.

Getting RF back into the amp seems a bit unlikely, though, because I always
tune my antenna for a 1.0 to 1 SWR, and always make sure my reflected power
is at or extremely close to 0, at least according to my TW1.

Will let everyone know if I can more consistently determine what is going
on.

Tom Behler: KB8TYJ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Steve Forst
Sent: Monday, March 10, 2014 8:25 AM
To: [log in to unmask]
Subject: Re: Need To Find A Replacement Radio

While I'm not quite sure what is going on for Tom, I'm pretty sure he is
referring to the T/R relays in the amp, not any sort of protection circuit
relay.  Since he did buy the amp used, it is remotely possible it has an
optional grid protection  circuit installed, but I would really doubt it.  I
don't think there are any relays on that board and you would have to  flip
the standby switch off and on to reset it and get output from the amp after
a trip.

73, Steve KW3A