[TenTec] Model 1225 SWR and Wattmeter Kit

[Jim Brown]

On 7/14/2014 6:58 PM, Bob McGraw - K4TAX wrote:
> Calculating power meters such as the LP-100A become a bit more costly. 

Right. It also reads peak power with decent precision. That's important 
if you want to be very competitive -- we are licensed for 1.5kW PEP, and 
readying that peak power accurately is important if you want to be as 
loud as possible in a contest, or in chasing DX.

AND the LP100A does a LOT more than measure power. See the link 
previously posted. It is, for example, a vector power meter, meaning 
that it reads the magnitude and phase of the voltage and current. This 
allows it to compute the real power, and the complex impedance of the 
load (in this case, the transmission line). For about $200 more, it can 
handle a second coupler, so you can monitor two radios, or you can 
measure the input and output of your power amp, as well as the complex 
input impedance of your power amp. It can also read the voltage received 
on an antenna down to -15 dBm (40 microwatts), so you can use it to 
measure an antenna's pattern.

So while it ain't cheap, neither is a Bird 43, and Bird 43 needs slugs 
for every power range and every frequency range. LP100A and coupler 
calibration is specified at 5% at any frequency, 3% typical, traceable 
NBS. So, as I see it, the LP100A is a real bargain!

My neighbor, N3ZZ, has a pair of LP100As in his very nice SO2R station, 
where I've operated in several contests.

73, Jim K9YC