This is a cheap-skate way of power output measurement that 
can't be beat. Here it has been modernized. It is good up to
30MC.

The pix shows a 24-28V, 40-60ma bulb which will take up to about 
8 watts. A 110-130V 4 or 7 watt bulb will take about 100 watts.

Keep the wiring short by using a small box. If you use heavy wire,
you can directly solder to the tip of the lightbulb and wrap a 
spiral around the base. I used a grommet to hold the lightbulb
and pinched a wire between the bulb base and grommet for ground.
With a 1:1 SWR, this thing will indicate powers to little above 
100 watts without shortening the life of the bulb from repeated 
flashing (SSB and CW has the effect of many turn ons and turn 
offs which wears out a bulb due to surge current).
If the SWR is high the bulb may be unusually brighter or dimmer
which is normal where there is a high SWR.
Do not look directly at the bulb but at the reflected light off 
of some surface becuase then the slightest change will be very 
noticeable.