DIRTY DISHES and clean signals the publication of The 50 MHz and UP Group of Northern California, Inc.

Volume 3 Number 8                  August, 1998

(Edited by Rex Allers, KK6MK)

Visit our web site at: http://www.nitehawk.com/rasmit/50UP.html

August Meeting: No Meeting this month!

The meeting should have been on Sunday, August 9^th, at 1 PM. Unfortunately, with vacations an other commitments, I was unable to schedule a presentation for the meeting this time. I am very sorry to say that we won't be holding the August meeting. Please accept your president's humble apologies for this failure.

Request:

If you have suggestions about topics for future meetings, please contact me. This is especially true if you know someone who could do a presentation for us.

- Rex, KK6MK

Officers for 1998

Contests and Events

Foothill Swap Meet - The second Saturday of the month.

Livermore Swap Meet - First Sunday of each month at Las Positas College in Livermore, CA, 7:00 AM to noon, all year. Talk in 147.045 from west, 145.35 from the east. Contact Noel Anklam, KC6QZK, (510) 447- 3857 eves.

ARRL 50 MHz-Up Contests

August 15-16 ARRL 10-GHz Cumulative Contest (1 of 2)

September 12-14 ARRL September VHF QSO Party

September 19-20 ARRL 10-GHz Cumulative Contest (2 of 2)

A special swap meet

Subject: [WSWSS] Swap Meet CM98

From: Larry Hogue <w6omf@cwnet.com>

Date: Sun, 02 Aug 1998 19:40:22 -0700

Hello to all.... Well the Weak Signal operators in Northern California are gathering again...We are going to try a swap meet, grip and grin, and just plain old bring you lawn chair and enjoy the day...Ill have the pop, water and a little shade...

Where... Here!!!! 7372 Paddon Rd, Vacaville, CA 95688

Date.....5 Sept 98

Time.....8:00-1200 Local Pacific time..

We have Mike Staal, K6MYC and his Lovely Bride, Myrna, WA6GXF from M² coming, Richard, KA6NBC of AntennaWorks joining, and working on Norm, KB6KQ of the famed Mini-Loops.

The day is planned as a easy day, just plain old gossip and Amateur Bull...

The place here is located just North of Vacaville, one mile west of the exit of I-505 and Midway road.. Soooo coming south on I-80 or I-505 you would turn right and proceed to Paddon Rd. Turn right and we are the second and third drive ways on the right... Look for the antennas. Coming north on I-80 or I-505 just turn left... hi hi

We have 5 acres, so I think we will be ok... Its a "Ham" swap meet... So bring your best and let me know if you need further directions or information...

Sue and I are excited and hope you can join us and share part of your Labor Day weekend...Don't forget the Livermore Swap meet is the next day...

We are only three miles north of the Nut Tree Airport and the Nut Tree Factory Outlets... Plenty of things to do...

Do we need to pick you up at the airport?? Does the family need a brochure?

What else??? Let me know and Ill fill...Many thanks and see ya soon...

-- 73 W6OMF LARRY & K6SUE SUE.

VHF+ WeakSignal NETS  

New members welcomed

We are always looking for more people to join and share with our group.

At the end of 1997 a vote was unanimous to reduce the dues back to $15.00 per year. It was also decided that a special rate of $25 for two years be implemented.

Please encourage anyone who might have an interest to join our group.

50 MHz & Up Group Minutes, July 7, 1998

The 50 MHz & Up Group held their July meeting at the Lockheed-Martin auditorium on the evening of July 7, 1998. Executives and directors present were: Rex Allers, KK6MK, President; Jim Moss, N9JIM, Vice President; Will Jensby, W0EOM, Treasurer; Bill Ogilvie, KQ6FY, Secretary; and Bob Johnson KF6KVG, and Jeffrey Pawlan, WA6KBL . There were 20 members and visitors in attendance. The focus of this meeting was a tune-up session for 10 GHz radios. For this reason, there was no speaker.

Several people brought in 10 GHz equipment to test and there was some high quality test equipment available. There were a couple of X-band TWTs, and Bob Johnson brought in his compact transverter to test. The first part of the 10 GHz contest is on August 15-16, and the second part is September 19-20.

T-shirts, with the 50 MHz & Up Group's logo printed on them, are now available. See other note in this newsletter.

Microwave Update will be held in October this year. Preparations for the Western States Weak Signal Society conference in October are continuing. There will be a full day of presentations on Oct. 3 at the Sunnyvale Hilton. 50 MHz & Up Group members who wish to deliver a paper are invited to contact Jim Moss. There are also 4 slots at Pacificon for 50 MHz & Up Group members to deliver papers.

In May's meeting the speaker was Larry Moore KM6IU, who gave an in depth discussion on traveling wave tubes. Larry brought in and loaned several technical manuals for 50 MHz & Up Group members to copy. They have now been copied and the originals have been returned to Larry.

de KQ6FY, Bill Ogilvie

Rubidium Frequency Standards

Corby Dawson has purchased a mass quantity of them, and will sell them to us at a special rate. For $350 each (assuming we can put together an order of 10 or more), you get a tested, guaranteed, and calibrated frequency standard. Contact Jeffrey Pawlan to place an order. (See Officers list at front of newsletter for contact information.)

50 MHz and Up Group Shirts are still available

The shirts will bear our club logo on the back in color and probably have our club name on the front. Members who have been to the June or July meetings have seen them. For those that have not seen it, the logo is similar to the image in the header of this newsletter. If you have Internet access you can see the logo in color on the Group WebPages listed at the end of the newsletter.

Prices are:

T-shirts $9.00

Polo Shirts $18.00

Sweat shirts $25.00

The polo shirts are short-sleeved shirts with collars and a few buttons at the neck.

Please decide quantities for any shirts you would like to order and contact me. You can call me at home (my telephone number is listed in the member list) or email me rexa@dnai.com or bring your order request to the next meeting.

Rex, KK6MK

Meeting Videotapes

Video was recorded for the presentations in the April and May meetings. I am willing to make a small number of copies of these presentations. The video won't be super-professional but should be watchable and provide most of the content of the presentations. If you missed either of the presentations, or if you want a permanent record to browse, copies of the tapes might be what you are looking for.

Two tapes are currently available on the following subjects:

Earth-Moon-Earth (EME) moon-bounce operation by Ron Hopkins, N6BQ, (Apr 7 meeting).

Ron discusses the basic challenges, shows and describes equipment, and even plays audio of contacts.

Travelling Wave Tube Amplifiers by Larry Moore, KM6IU, (May 5 meeting).

Larry shares his knowledge on the function, construction, and operation of TWTs and Klystrons. He also offers some suggestions for hams who are searching for tubes, and some insight on how tubes could be adapted for ham-band operations.

The cost will be $7 per tape. Contact me if you are interested.

- Rex, KK6MK

10 GHz Amplifier article

This has been published several places previously. Proceedings of the 23^rd Eastern VHF/UHF Conference, 1997, is one publication. Thought it might be of interest. I have also seen these devices in a Mitsubishi Ku-band transmitter unit that was sold at Foothill swap a couple years back.

W1RIL (1) 2W -10 Ghz Amplifier

10/31/95

The availability of the Microelectronics Technology Inc. Ku band power amplifiers on the surplus market has resulted in a gold mine of parts for 10 Ghz operators. This white box not only contains 1 or 2 watt (sometimes 1 and 2) Imfet devices but also the Vdd and Vg power supplies needed to run them. The 2 watt device makes an ideal "afterburner" for the 1 watt Qualcom strip available from the West coast (2). The box is massive and makes an ideal heat sink for the unit.

Two internal amplifier boxes, complete with covers, contain ceramic subtrate gold microstrip. This stuff is so small it requires a jeweler's loop to even see it. Modifying this gold microstrip is not a task to be undertaken on the Amateur workbench! I decided to strip the box, save the screws and other useful parts and make a new board to fit the box - one that I could see, at least partially, without the aid of the jewelers loop. See FIGURE 3.

The new board is mounted in a cut down section of the original amplifier box the cut end of which has been fitted with a new brass plate made from .060 stock. A brass carrier cut to the size and shape of the board is fashioned from .032 sheet stock. The board and carrier are screwed down to the box bottom using 0-80 ss cap screws previously removed from the box. Before this is done however the original device landings in the bottom of the box are removed by milling flush with the rest of the box bottom. You will find that many of the 0-80 screw holes are already in the box bottom. It might be a good idea to leave the hole locations off the board and carrier and custom fit the holes to the box as some boxes may have different hole locations than others. The new hole locations can be added as required.

A schematic of the amplifier is shown in FIGURE 1. A few comments about the RFC's are in order. These are .005 - .006 mil lines. Attempting to get these on the board by etching is an almost impossible task. Strip the insulation from a short length of #20 - #22 Teflon coated stranded wire. Remove 1 strand of the silver plated wire from the twisted bundle and stretch it slightly to straighten. Solder to the 50 ohm lines and to resistors R1 and R2 keeping the wires straight and flush with the surface of the board. Also solder these lines to the apex end of the quarter circle bypass / decoupling capacitors. These capacitors have a radius of .207 and have smooth edges. (despite what my computer shows! )

Tuning the amplifier is done by adding stripline pieces - see FIGURE 4. The grey areas on the 50 ohm line were added to tune the amplifier for maximum output into a 50 ohm load. Please note the step in the line at the device input. This is actually a taper (my computer wont do that either!) The line is tapered to the width of the device input gate. Taper the line from .046 to .022 over 1/2 the distance from the RFC to the device input.

The amplifier gives the following results:

+28 dBm (640mw) input => +33.4 dBm (2.2W) output

Vdd = 7.48 ~ 720 ma.

Vg = -1.28

I would like to thank Bruce, N2LIV for supplying the Tfe board for this project and Don, WB1FKF for figuring out the power supply capabilities. Without their help I'm sure this project would not have come to fruition.

(1) Ken Schofieid, 21 Forestdale Rd., Paxton, MA. 01612 Tel. 508-757-3966

(2) C.L. Houghton, San Diego Microwave Group

W1RIL 10 GHz Amplifier

Figure 1. Schematic diagram of 2 watt 10 GHz Amplifier using K33M IMFET.	Figure 2. Layout view showing parts and locations.
Figure 3. Board artwork to fit modified Microelectronics Tech Inc. box. Ckt board Rogers 5880 Duroid. 0.015 mil, er 2.2.	Figure 4. Circuit board after tuning. Added stubs shown in grey hatch.
The completed amplifier in its modified original box.

On the Internet…

Do you have a Web Page relevant to our members? Let us know and we will put it here. (You must be a member.)

50 MHz and Up Group page: http://www.nitehawk.com/rasmit/50UP.html The official group web page. Hosted by Rein Smit, W6/PA0ZN as part of his Weaksignal News Kiosk. The 50Up page includes an archive of newsletters.

ARRL Pacific Division Web page:  http://www.pdarrl.org/
Ham RF Exposure Guidelines Effective Jan. 1, 1998: http://www.arrl.org/news/rfsafety
Vanity Call Sign Gate 4 to Open Dec. 2, 1997

Rex's Place - KK6MK: http://www.dnai.com/~rexa/ Microwave stuff, 50 MHz Up Group pictures and information.

Laser Communications Home Page! http://www.qsl.net/wb9ajz/laser/laser.htm Lots of bright stuff.