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[Amps] AL 1500 P.O. Meter Function

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Subject: [Amps] AL 1500 P.O. Meter Function
Date: Sun, 04 Oct 2009 21:49:52 -0400
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I need some help.  Upon receipt of my new AL 1500 I noticed that the Multi 
Meter P.O. "Power Output" function indicated 1,100 watts output on 40 meters 
and similar low output readings on 15 meters.  In all cases the load is a 
Hygain Hytower with VSWR at 1.5"1 or less on the frequencies tested.  After 
talking to the factory they had UPS pick up the amplifier and it along with the 
tube were returned to Ameritron.  I was given priority as it is a new unit.  My 
contact at Ameritron couldn't find anything wrong with the amplifier and 
promptly returned it to me after asking question regarding my line voltage and 
whether or not I may have had the ALC connected.  My drop is connected directly 
to the electrical box, 12 gage wire and the AlC was not connected.  I asked the 
Technician on more than one occasion regarding the P.O. Multimeter and the 
accuracy of the Power Output and was assured that it was an accurate indication 
of power output.

After receipt of the Amp it behaved exactly as it did when it left my home.  
Over the weekend I inserted an additional piece of Coax, RG 8214, approximately 
24' long in line with the antenna and the amplifier and got significantly 
different numbers.  I was driving the amplifier in all cases with a FT 1000mp 
Mark V Field with 50 watts indicated output power.

The P.O. Meter now indicated somewhere between 1,500 and 2,200 watts depending 
on the band.  All were checked with the exception of 160 for which I have no 
load at this time.

I also used a scope, TEK 2235 connected to my EWE antenna to monitor the 
transmitted RF of both the driver and the amplifier.  Using these numbers I 
extrapolated the gain in decibels, converted it to gain and multiplied the gain 
by the driver power (50 watts).  Considering the drive, 50 watts the results 
seemed reasonable, if not somewhat optimistic with power outputs approaching 
1,500 to 1,800 watts.  

My guess is that the power meter in the AL 1500 is really a "Relative Power 
Output" meter, not a Power Meter.  The power meter reading should not be 
dependant on where you place the meter in the transmission line, or at least I 
would not think so.  

I am not complaining about the amplifier, overall, I would make the purchase 
again, based on cost/benefit.  

My guess is that this is a RF sniffer circuit which is good enough for a tune 
up process but not what I was expecting.

If it is truly a watt meter then there is another problem.

Thanking you in advance for your thoughts.



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