"Richard Clark" wrote in message
...
On Sat, 2 Feb 2008 08:45:27 +0000, Ian White GM3SEK
wrote:

As with the AN-URM120, the Bird design adjusts the coupling so that all
detector diodes in all the inserts are operating at the same RF levels,
so they can all share the same meter scales. The difference is that
instead of physically moving the same insert inward or outward to adjust
the coupling, Bird do it by selling us more slugs :-)

Hi All (Congratulations Ralph),

There are more differences than that. The Bird suffers more from
parts erosion than the URM120 as the URM has bigger elements. With
the bigger elements, the geometries are held to a tighter precision.


I was luckey enough to find one that was in the origional wrapping paper. I
don't remember what the date was on the wrapper. At a hamfest several years
ago soneone had several new ones. They were in the heavy duty aluminimum
foil , cardboard box, and the hard plastic foam filled case. Never opened
from the day they were calibrated about 10 or 20 years before. It came
with 3 elements that would go from about 3 mhz to 1000 mhz. Think it topped
out at 1 kw up to 30 mhz and 500 watts after that. I bought it for what
some used Birds without elements seem to go for on e-bay now.
One minor thing is the meter movement on those meters are sluggish so it
takes a slow adjustment of amplifiers to get them to the max output.