[Amps] AL-1500 for legal-limit 160m AM?

[Jim Barber]

Rob,

I'm running a couple of hundred feet of Davis Bury-Flex. It's worked at 
(legal) QRO levels from my Alphas on 75M AM, RTTY, SSTV etc without any 
meltdown issues. Of course I at least try to keep the antennas somewhere 
in the vicinity of 50 ohms with minimum reactance. 160M AM and 160M in 
general are relatively new to me - we finally bought a house with modest 
acreage and a few trees, which makes such things easier.

The main station amp will eventually be a YC-156 that I've been fiddling 
with for a number of years. It's in a zillion pieces now, but I may get 
back to it yet this winter. Every time I get close to having it 
completed I decide to redesign it and the game starts over again. This 
next incarnation is being built into an MRI amp cabinet, then "skinned" 
with a thick shell of mineral wool encased in something, maybe plywood 
with a furniture finish. (haven't decided yet) The house will be 
sporting a new dryer vent and the operating desk a remote console for 
keeping an eye on the beast.

I was kidding about the wife - she's actually quite tolerant of my 
hobbies. (of which amateur radio is only one) It's actually me that's 
tired of boat anchors. ;-)

73,
Jim N7CXI

On 12/30/2011 9:15 AM, Rob Atkinson wrote:
>> When I need QRO I have
>> a couple of healthy Class C amps in another part of the basement along with
>> boatanchor RX and TX's.
>
> I agree--300 - 400 w. ain't QRO : )
>
>> My wife has this thing she swings in front of my face (a shiny bit on a
>> string, or was it her fist?)  - "No more boat anchors... No more boat
>> anchors..." ;-)
>
> That's too bad.  You miss out on some of the highest build quality
> gear available because of that.
>
> After the maximum blower speed, the next thing to consider is:
>
> What do you have in the line between the feedpoint and the AL-1500?
> If this is your first time running a few hundred watts or more key
> down, any el-cheapo stuff in the line won't hack it, especially on 160
> m.
>
> You should have some sort of monitor scope set up -- personally I like
> an ersatz trapezoid taken from an RF sample of the exciter and power
> amp output that gives me some notion of linearity, and up and down
> modulation peaks.  You may prefer simply using an oscilloscope to see
> the modulation envelope picked off the amp output--it can show you
> things you may not hear like very low frequency audio hum riding the
> carrier.
>
> 73
>
> Rob
> K5UJ
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