Need info. RF ammeter Delta electronics

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WB4AIO:
Quote from: W7IXZ on August 17, 2010, 02:34:16 AM

These units were used to replace the crappy thermocouple ammeter in ATU's, phasing units and transmitters. The 5 amp power range has nothing to do with actual power as that was determined by current squared times antenna resistance.  In BC, we bridged the tower and that determined the range of the ammeter needed.  5 amps flowing into a 100 ohm tower would be 2500 watts, but a very short tower with a drive impeadance of 10 ohms and 5 amps would only be 250 watts.  The current carrying lead goes through the hole in the transformer and there is a calibrated length of coax that connects the transformer to the meter.  It does not need power as it is just a rectifier.  The nine pin "D" connector is for remote control.  It can control a relay in the metering unit to turn it on and off, and it also provides a remote reading voltage to use with a remote meter in the transmitter building or to drive the sample port of a remote control unit.  I may have the info on the pin connections.  I will look for it.
Larry W7IXZ



Larry is correct on all counts. I used to work with the sales manager at Delta, John Bissett, on numerous projects including the installation and use of these meters. I used five of them at WEAM in Arlington -- one for common point current, and one for each of the four towers in the directional array.

They read true average current, and are not affected by modulation on AM signals -- unless your AM signal has carrier shift, which will be shown. Only one conductor should pass through the transformer.


With best wishes,


Kevin, WB4AIO.

ke7trp:
Not much use for me then. Thanks for the info guys.  This ones new in the box with all the parts and cables.

C

W7IXZ:
New they sell for over 500 bucks depending on the model.  At least that is the price I paid for the last ones I bought many years back.  They are useful if you know the resistance of your load, and can be used in a dummy load of known R (like a good 50 ohm load).  Run the center conductor of the coax through the hole to the load.  I use one to measure the power to my 160 meter inverted "L", but one needs to bridge the final antenna to determine what power the current is indicating.  I do have the diagrams if you want them or you can down load them from the Delta Electronics home page. 

W7IXZ

K5UJ:
Quote from: W7IXZ on August 17, 2010, 08:46:44 PM

New they sell for over 500 bucks depending on the model.  At least that is the price I paid for the last ones I bought many years back.  They are useful if you know the resistance of your load, and can be used in a dummy load of known R (like a good 50 ohm load).  Run the center conductor of the coax through the hole to the load.  I use one to measure the power to my 160 meter inverted "L", but one needs to bridge the final antenna to determine what power the current is indicating.  I do have the diagrams if you want them or you can down load them from the Delta Electronics home page. 

W7IXZ


Larry,

How long can the coax be from the N jack on the transformer to the volt meter?  I have one of those transformers.  don't have the meter though.  I was going to (one of these days you know how that goes) simply try putting a meter sitting around here in a box with a N jack on it and see how it goes.  Sounds like the run from the transformer to the meter should be no more than a few feet.  The Delta xformer i got only spec'd up to 2 mhz.  If you could point us to the Delta URL for downloading the diagrams that would be great.  tnx

Rob

John K5PRO:
I worked there (at Delta) with John Bissett for a few years. The TCAs and TCTs are one of their breadwinners. TCA is the ammeter, and TCT is the current transformer when used with a phasor, to drive a phase monitor. The ammeter box in the TCA has a nice compensated diode circuit, with two diodes, that remained accurate with temperature fluctuations. They sold thousands of those things, and recalibrate them. They don't go above a few MHz. For higher frequency current transformers, go to Pearson Electronics. They don't have the rectifier and Beede meter however.

If you don't find the info, I have a copy of the single sheet manual and also a white paper on the design, by the late Charlie Wright of Delta Elec.

About 8 years ago a guy at HP contacted me wanting to know about the TCA. They designed (copied) something like the Delta circuit into one of their Detector ICs for Wireless.

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