[BC] Barry asked for my long winded response on 12 tower metering.

[Dave Hultsman]

In a message dated 11/11/2010 3:57:02 P.M. Central Standard Time, barry at oldradio.com writes:
>Maybe Dave Hultsman will tell the tale of his 12-tower in Dallas at
>KLIF.  Something about an endless chore....
 
Live from Portland, ME tonight
 
On the 12 tower we logged the following;
 
Hourly and half hour
 
Plate Voltage
Plate Current
Common Point
Frequency  (still had to do that)
 
Once an hour we logged the following
 
Reference tower #3  = Read and set to 100%
Tower #1  Phase,  Ratio,  Deviation from Ratio
Tower #2  Phase,  Ratio,  Deviation from Ratio
Tower #4     "           "                "
Tower #5     "           "                "
Tower #6     "           "                "
Tower #7     "           "                "
Tower #8     "           "                "
Tower #9     "           "                "
Tower #10   "           "                "
Tower #11   "           "                "
Tower #12   "           "                "
 
The system was originally considered a "critrical array".  The required a Precision Phase Monitor.
Vitro (Nems-Clarke) had manufactured a model to meet the FCC requirements.  They went out of business and David Harry, Bob Ellenberger and Cliff Hall formerly of Vitro, I believe formed Potomac Instruments.  I went to the NAB in Chicago looking for a 12 tower Precision Phase Monitor and none of the manufacturers were aware of any monitors but everyone told me that there was no more Nems-Clark.
 
I ran into Vir James, Consulting engineer from Denver at one of the NAB engineering sessions.  I asked him what he was doing about phase monitors.  He told me about a new company  Potomac Instruments that was not on the NAB floor but had rented a hotel room in the Conrad Hilton.   He gave me the room number and I called an made an appoint to stop by the next day.  I met Dave and Bob at that show in 1967 I think.
 
For many years their brochures had photographs of our 12 tower AM-19D  to read the phases and ratios to 0.1% and 0.1 degree and the PMA-19 Precision Monitor where we read the deviation from ratio digitally.
 
The meter readings were bad enough for the operator, the real problem was reading the base currents daily.
There were two parallel rows of six towers 432 feet between them. In the four end towers the Weston 308 RF Ammeters were very low scales and moved like VU meters, which definitely required the muting of audio to get an accurate meter reading. Programming wanted us to do that after 10 PM what a drag.  I wanted the done after an hour of operation so all the component heating had stabalized.  It was nearly impossible to read the base meters and get back to the transmitter to read the 30 minute transmitter readings.  We also ratioed the tower base currents to the reference tower after logging each evening.
 
Ralph Dippell and I tried to convince the VP of engineering to get an auto-logging system but the cost was pretty extreme.  It was a small percentage as compared to the overall cost of 160 acres, 12 towers,  8 years and three or four pattern designs at two sites with consultants and lawyer to get to get the FCC to accept for filing.
 
It is no longer a "critical array".
 
Dave Hultsman