External Exciter with Armstrong X-1000B

[bmcglynn]

I recently purchased a station with an Armstrong X-1000B 1KW AM Transmitter. I have an external exciter that I would like to use with the X-1000B and wanted to see if anyone had any experience with the unit. I noticed from the literature that the unit is "HD Ready" and there is an alleged RF Input connector, and was curious about feeding this unit with the RF from an external exciter.

Does anyone have any experience with this unit? I would assume that using an external exciter would depend on how linear the amplification path/mode of the unit is.

Thanks in advance.

--
Brian McGlynn
Genesee Media Corporation

 

[Dale H. Cook]

I have an external exciter that I would like to use with the X-1000B

Remember that if you substitute an exciter other than the model provided with the transmitter you will have to measure the system with a spectrum analyzer.

 

[bmcglynn]

I have an external exciter that I would like to use with the X-1000B

Remember that if you substitute an exciter other than the model provided with the transmitter you will have to measure the system with a spectrum analyzer.

Absolutely. Plus an oscilloscope, an audio generator and an audio analyzer on the receiving end to measure distortion.

 

[frankberry]

An external exciter may work to provide the un-modulated RF.
If the exciter is modulated, it may not work.
I doubt that the output modules are linear.
The transmitter probably uses some variation of pulse width modulation.
The external RF connector may have been originally designed for AM stereo.
What are the specs for the external RF input? How much RF power is required from the external exciter?
The best way to find out is to try it.

 

[bmcglynn]

An external exciter may work to provide the un-modulated RF.
If the exciter is modulated, it may not work.
I doubt that the output modules are linear.
The transmitter probably uses some variation of pulse width modulation.
The external RF connector may have been originally designed for AM stereo.
What are the specs for the external RF input? How much RF power is required from the external exciter?
The best way to find out is to try it.

Thanks. I checked the schematic of the X-1000B the external RF input can take TTL-level RF in the 5-12V range. The unit claims IBOC up/down gradability, so I can imagine that the designer was leaving a provision in for the system for expansion when the X-1000B was designed in the early 2000's.

The external exciter I plan to connect is a BE AX-10 and it can output TTL-level RF as well. From the schematic and block diagram, it looks like I can feed the RF into the final power amp and use the audio from the AX-10 to feed the transmitter's modulator.

I'll need to take out the dummy load and do some testing at low power and low modulation to see how it performs. I figured I'd see if anyone on the board had some experience with these units.