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Old 4-Apr-2013, 5:43 PM   #3
tripelo
Senior Member
 
Join Date: Jan 2010
Location: Dallas, TX
Posts: 123
Thank you GroundUrMast, for your kind words.

Quote:
Originally Posted by GroundUrMast View Post
Are the signal source and/or power meter proprietary works? Or can you share details of those with us also?
No, not proprietary. Yes, can provide some details.

The synthesizer is based on IC Silicon Devices SI570. PDF available here:

http://www.silabs.com/support%20docu...docs/si570.pdf

The version (BBB) that covers range from about 10 MHz up to about 950 MHz was used.

Some kits containing major parts of the circuitry and components are available from SDR hobbyist groups. SDR=Software Defined Radio

http://en.wikipedia.org/wiki/Software-defined_radio

SDR-Kits were used in this particular synthesizer.

http://sdr-kits.net/QRP2000_Description.html

The components are not complicated to assemble, nearly all were thru-hole. The synthesizer IC is SMD (surface mount).

One should have output attenuators, power supply, metal housing, and filters. Other modifications and items are useful, but with these become quite useful. USB power can be used when near such, otherwise wall wart with additional filtering can be used.

The controller for the synthesizer chip is USB based.

Software to control the synthesizer from PC can be obtained on the web.

For remote control one can use USB to LAN adapters at each end of the circuit, then use whatever LAN devices one desires in between.

In this case, for remote control, ~165 feet of Ethernet LAN CAT5e cable was used, probably beyond specifications without repeaters, but worked fine. To reach greater distances, one could probably use wireless game bridges, or something similar.

The wideband power meter is based on Linear Technology LT5534 integrated circuit.

http://www.linear.com/product/LT5534

Haven't seen a kit of parts for such.

Manufacturer provides a good reference design. Found a PCB made for another similar part and adapted it. It is all SMD.

For accurate results, one should provide for a matching circuit on the input. Resistive pad matching at input combined with ~ 10-20DB fixed attenuation provides a reasonably low SWR. Can use ordinary DMM for digital readout.

Need: power supply, metal housing, and external attenuators.

Below is an image taken in 2011 around the time of the preceding test. The workbench is behind that window, inside the building next to the receiving antenna mast.



Shown on part of the workbench, among cables, planks, and bricks; from top to bottom, left to right:

- Some version of Research Communication preamp (loose)
- Blonder Tongue FSM-11 signal strength meter with brick
- Antennacraft preamp power supply (loose)
- Signal synthesizer (in aluminum case)
- Half Wave Loop balun
- DMM (Red)
- HP notebook computer
- Holland Splitter
- Various fixed attenuators (in-line)
- Another Research Communications preamp (in-line)
- Power Inserter (in-line)
- Winegard Power Inserter (loose)
- Fixed attenuator (Red, in-line)
- Wideband power detector (blue aluminum case)
- Some version Winegard preamp
- Channel Master preamp (loose)


Quote:
Oh, nice towers.
Thank you.

The near tower has the transmitting CM-4228. Hard to see, it is mounted directly behind the CM-4251. The tower and that particular CM4251 have stood for more than 40 years.

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Attached Images
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