PfruiG D; OW Ong/nat home-built spectrum analyzer showing five stages of tog amplifier, power sweep circuits, RF preamp and filter, and VCO mixer circuitry

you will appreciate its dynamic range, abilities, and usefulness in spectrum analyzer appJicatkins. I mentioned earlier thai wtLh a tog amp. a filter, and an RF amp/local oscilEator you can make a small unit that is capable of display ing data on almost any type of o-scope However, as I stated earlier a long-persistence type unit would be best, similar to a heart-rate display monitor.

The basic system for a spectrum analyzer can be easy to set up. Using a TV tuner front-end removes the construction of both the tracking RF amplifa er and oscillator requirements. Now only the filter and log amplifier units are required if you can find a medical heart rate monitor (it has the sweep circuits). Hope you have good !uck checking out your local swap meets and surplus material sources for equipment.

Mailbox Comments

Sean KB8JNE of Milliard, Ohio, writes that he wants me to mention in the column mat there must be quite a few Columbus, Ohio, area amateurs with 10 GHz equipment in their basement or attic He is interested in seeing if those who have equipment are willing to dust it off and give it a try again. He says most of Ihe folks around there have prayed with it (10 GHz) at one time or another, but found the band empty irt the area and filed the equipment away. If that's the case, get the equipment out and contact Sean KB8JNE, 3700 VYeStbrook Drive, Hiltiard OH 43026 He would like to organize a local microwave enthusiast group m the Columbus area. Drop him a line. Sean. 1 hope you get a good re sponse to your efforts.

Arthur W1PXL wrote to inquire about an antenna noise bridge for VHF/UHF use and asKed about schematic information on the construction of such a unit. Weil, there is an antenna noise bridge for 1.8 through 30 MHz in the ARRL Handbook. V989 edition, pages 25-32. The same circuit appears in the ARRL Antenna Handbook, 1988 edition, pages 27-15. A similar circuit appears in the RSGB Handbook. 4th edition. 1933, pages 11.19-11.20. This unit covers low frequency to 200 MHz and will give good results 10 432 MHz. The books from the RSGB. Radio Society of Great Britain, are quite good and describe almost ai] circuits in great ciahty of construction. Most see^ to be based on a heavy involvement in home construction. They re good books to have on the bookshelf ^

Carl AA4H writes thai he recently purchased a mufti mode VHF transceiver. He found many stations to work on G and 2 meters and a fair amount of activity on 70 cm; however the activity levef on 222 is very disappointing. He reports making only a few GSOs on 222 MHz and most were in the UHF contest except for a few locals. Why is there such a lack of 222 MHz ac^ tivity^ Is it because of the recent loss of the bottom 2 MHz? Cart wants others to use this band as he feels we will Jose further parts of the band if we do noi increase our activity in this area. For further information, contact Car] AA4H at 5971 Hwy. 126, Bfountvilie TN 37617,

Well that's it for this month. Next month i plan to start a construction project modifying an S$B transceiver lor microwave use Firsl I will present a basic 26 MHz platform constructed dead-bug styJe, showing a simple system. Later we will cover a converter to 2 meters using two of the Hamtronics modules to wrap up the 28 MH2 to 2 meter SSB transverter. See you next month. As always, t will be glad to answer questions on ihis or related topics. Please send an SASE for prompt response—family, contest and workbench time permitting, 73 Chuck W86iGP. ES

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