[BC] BE tuner and such

[Alan Alsobrook]

Ronald J. Dot'o Sr. wrote:
> [After I got the TX to match the tower I would have liked to read the
> ATU input values for future reference but the owner was in a rush to
> get back on the air, so I didn't.]

I know the feeling well, "It's working so we're done!"

> [ I connect the long lead, clear of any obstructions, to the
> measuring point and then short it to ground with a very short clip lead and
> balance the bridge, remove the cliplead and then do the reading so the 
> leads should not be a problem.]

As you state later you are using a 916.. of course my answer was written 
mostly thinking about an Delta OIB.

> [I have a GR 100 ohm precision resistor that came with the GR 916A
> bridge and measures 100 ohms exactly.  The bridge reads 100 ohms and
> 0 J with the resistor.  FWIW I have two 916A bridges and they both
> read the same.  I have read towers that were previously read by consulting
> engineers and got the same readings so I guess all is in order :-).]

At this point I would trust the bridge.

> E. Someone overlooked a range shifting switch in the wrong
> position. (Of course I've never done that myself..)
> 
> [I'm not sure what you mean by a range shifting switch but if it's
> there I've probably done it. ;-)  Do you mean the C/L switch on the
> bridge?  

As this was written thinking of the OIB, the range switches don't exist 
on the GR. On the Delta you have a 0, +100, +200 as well as a separate 
0, +300, +600 on the OIB3 for each of the dials.

> [Well, the TX seems happy for several years now with minimum
> reflected
> and the occupied bandwidth measurements are all good so I'll just
> let sleeping dogs lie.  As we used to say in SAC: "If it ain't broke
> then don't fix it!".]

If it's working some times that's best, other times it's not. It would 
be nice to know the exact cause of the error. My B. Point that got lost 
was that a transformation is occurring somewhere between the ATU and the 
transmitter. This could be caused by wrong impedance coax, bad coax, or 
undersized coax (Like RG-8 trying to take 1 KW).

-- 
Alan Alsobrook CSRE AMD CBNT
St. Augustine Fl. 32086 904-829-8885
aalso at Bellsouth.net