Iq

Figure 4. Schematic for the 100 MHz oscillator. Y1 is 85 to 106 MHz, depending on the frequency desired.

Emich). 10 Howard St., Buffalo NY 14206, tel. (716) 052-3711, will accept orders for brass waveguide. Cost is $6.50 a foot, plus shipping.

Two- to three-fool lengths are just right for construction of feed systems for dish antennas, with larger sections used for tow-loss home station runs. For comparison, I used some 40 feet of waveguide in my home station on 10 GHz, putting all microwave hardware and high power amplifiers inside the shack for easy modifications and adjustment.

Emcom is currently developing a cavity wave meter for frequency determination (10 GHz) and has other mi-Crow ave-rei a ted projects in the mill. I will provide details as i receive them

Mailbox Comments

Ed Cole AL7E8 writes that he plans to start 10 GHz operation when he returns from his job in Valdez, Alaska. He says he has collected several CG-176/ U couplers and an assortment of 1N23 type diodes to start construction with. He has two military surplus weather-tight boxes that he gutted to hold the 30 MHz IF preampgunn control, CW iDer, and a MA/COM gunnplexer.

His home is in Hope, Alaska. With Anchorage only 25 miles north over the water, Ed plans line of sight communications from the top of his tower to Anchorage. Later, Ed wants to try a shot across Cook Inlet, from Homer. Alaska (1000-foot Diamond Ridge), to Kodiak Island, about HO miles to the south Ed says it has been over fifteen years since he was last on microwave, and he is looking forward to getting back on.

Mike Baker in Gainsville, Florida, writes that the local group is interested in putting a beacon on a TV tower and needs a set of plans for construction of "omni 10 GHz antennas " Mike mentioned the slot antenna, and I sent him copies of this design. A 10 GHz slot antenna requires severaf slots (about: six to a side) centered about the middle of the waveguide. The slots couple RF out similar to the way a stacked monopole antenna does.

Our microwave group is experimenting on omni antennas for both horizontal and vertical polarization. The polarization is affected by the placement (front, face, or side) of the slots in the waveguide Slot dimensions are critical. and while you can construct the antenna at home, it requires care.

At present I don't know of any company selling slot antennas for the amateur budget. Commercial slots manufactured to mil-specs cost accordingly—sky high. I am in the process of testing several variations on the beacon slot antenna, and 1 11 inform you of results as they develop.

Mail-Box Material

Due to the large volume of mail I receive, next month this column will be dedicated to questions and answers from you, the readers. Going over common problems with circuitry and application, we should be abte to clear up some of the basic questions you have submitted to me. Future columns will cover the 6 GHz system I am building, and I wiil tet you know what I find out about the surplus 6GHz equipment.

Let me know about the systems and frequencies your construction projects involve, and let me know if you have any photos of them for the column. This is your column Write to me about any ideas you'd like to see developed. I hope you are as wild as I am about building; it's a germ we need to spread around. As always, I will answer questions related to this and other VHF/ UHF or microwave items. For a prompt reply, please send an SASE 73t Chuck WB6IGP E3

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