Technical Articles and Projects

Last Modified January 8, 2013


70 CM Preamp Conversion from 9003B Digital Rcvr. This conversion by Art McBride,
KC6UQH involves a tiny board approx. 7/8 by 1 1/4 inches. (8/10/2010)

Optical Communications Projects. A collection of projects using lasers or
high power LEDs for communications over line-of-sight and non line-of-sight
distances.(17 Mar 2008)

Doppler sounds from the US Navy NAVSPASUR VHF RADAR Fence (Oct 30, 2006)

47 GHz Articles and Experiments. A collection of info becoming available about
building and testing gear for the 47 GHz Band. (November 25, 2003)

P-com 23 GHz modifications to 24 Ghz. A collection of info becoming available on
how to modify these units for 24 GHz amateur use. (Revised 10/30/2010).

Converting 12 GHz TVRO Low Noise Block Converters (LNBs) to 10 GHz Low Noise
Amplifiers (LNAs) with excellent Noise Figure and Gain. - Chuck Houghton, WB6IGP.
Photo of unmodified LNB. Article in Adobe Acrobat (.pdf) format. April 2002.

The San Diego 10 GHz All-Mode Repeater. This is from a 1996 Microwave Update
article by Kerry Banke, N6IZW. It details a repeater which was in operation for
several years, allowing local microwavers to communicate between home locations
when the direct paths were not workable. The repeater is currently off the air
due to site access problems. Article in Adobe Acrobat format. (Added here 11/13/03).

Polaplexer Design & Construction - Ed Munn, W6OYJ, Oct 1999

Project Photos by Jeff Keyzer, KF6PBP. 10 Ghz NB Xverter from modern
Qualcomm hdwe; 1296 Xverter from Qualcomm hdwe; 24 GHz Wideband FM
Gunn XCVR. (Link to Jeff's web pages). Jan 2001.


Qualcomm Hardware Modification Articles, Revised 8 January 2013
Note: These mods and descriptions are of amateur radio origin and are not
by the Qualcomm Corp, which has generously allowed amateur access
to the materials for amateur use only. Please do not contact Qualcomm with
any questions about these items. Instead, contact the authors or the
Microwave Group of San Diego at the following email address: or write to Kerry Banke, N6IZW , 6026 Poppy Street,
La Mesa, CA 91942.

Using the Qualcomm 1152 Board Power Supply. This power supply operates from
+12V DC and produces both +5V and +15V for the RF and digital portions of the
original transceiver. The brief article by Ed Munn attempts to document the use
of the power supply and its interconnection details. (8/3/2008)

Qualcomm older Omnitrak "Brake Drum" photo with labels identifying the
different pcbs, and labelled photo of the Tx i.f. amp pcb. This amp covers 0.6-
1.6 Ghz with about 25-30 dB gain and max Po approx +10 dBm. NF around
7 dB. The Rx i.f.amp has about the same freq. coverage and gain with NF
about 3 dB and max Po approx +3 dBm. The Upconv Tx mixer pcb is the one
Kerry Banke used in his Noise Source Project mentioned below. The diodes on
that pcb are useful well above 24 GHz. (1/1/2003)

Globalstar "Round Boards". Photos with labels by Kerry Banke N6IZW showing
how these boards can provide a 1-watt PA for 1296 Mhz, and a LNA for 2.3/2.4 GHz.
The PA was also described in the article below on these pages entitled "1296
Transverter Project". The board has a narrowband 2.5 GHz filter ahead of the LNA
which must be bypassed in order to use it for 2.3/2.4 Ghz with an external filter. The
LNA has excellent performance and a capability to handle high signal levels without
intermod or desensing problems. Photo of original board. Photo showing PA section.
Photo showing LNA section. A more complete description will come later.(12/4/02).

Globalstar 1.6 GHz 5-8 watt PA mods to 1.3 GHz. Article by San Diego Microwave
Group Members shows a simple modification to lower the frequency range of this
linear amplifier to operate in the 1296 MHz region. (5/25/02)

"X4 Multiplier" for 10-12 GHz. Multiplies synthesizer outputs in the 2.XXX GHz
range to 10-13 GHz. Small pcb measures 1 5/8 by 2 3/4 inches. Can produce +7 to
+10 dBm output. See Photo. Originally designed for 2.6 GHz X5 to 13.1 GHz. New
Modification Article by Chuck Houghton, WB6IGP describes changes for 2.5XX input
and 4X output in 10.224 to 10.368 GHz range. (August 2001).

"1152" Synthesizer Board.
Frequency Range 750 MHz to above 1152 MHz
*** Photo and Description ***
*** Modification Article *** Kerry Banke, N6IZW, April 2000

"1152L" Large Synthesizer Board
Frequency Range 750 MHz to above 1152 MHz
*** Photo and Description ***
*** Modification Article *** Ed Munn, W6OYJ, March 2000

"Texas" Synthesizer Board
*** Photo ***
Frequency Range 2.1-2.6 GHz. Dual-frequency switching capability.
Output approx +14 dBm. Modification Article, Ed Munn, W6OYJ,
October 2001, See also "Synplexer" article in 1999 Microwave
Update Proceedings, pp 117-126, Ed Munn, W6OYJ, October 1999

"3036/3216" Rectangular Synthesizer Board
Frequency Range 2.1-2.7 GHz.
*** Photo and Description ***
*** Modification Article *** Ed Munn, W6OYJ, Feb 2001

"3236" Synthesizer Boards
Frequency Range 2.1-2.7 Ghz
*** Photo and Description ***

"10 GHz Transverter" Modification of 3236 Synthesizer Board
*** Modification Article *** Kerry Banke, N6IZW, see also 1999 Microwave
Update Proceedings, pp 127-140. (Corrections of July 2000 included).

"1296 Transverter Project"
Using the 1152 Synthesizer and other salvaged assemblied
*** Article *** Kerry Banke, N6IZW, December 2000

"Microwave Noise Source Project"
Broadband excess noise source from salvaged components.
*** Article *** Kerry Banke, N6IZW, December 2000
***Schematic of Power Supply*** for above by Sam Luitwieler, K6VLM
December 2000 (in Adobe Acrobat Reader .pdf format)
***Schematic of Modified Power Supply by Ed Munn, W6OYJ
May 17, 2005 in Adobe Acrobat Reader .pdf format.

Microwave Stripline Retuning Procedures. C. L. Houghton WB6IGP.
Link to this Feb '97 "Above & Beyond" article describing talk given at
ARRL SW Division Convention by Kerry Banke, N6IZW.

AF1T 10 Ghz QUALCOMM Modification Notes, Dale Clement, AF1T,
Excellent (1995) text of 10 Ghz 1 watt PA module modification and Rcvr LNA
board modification. Figures are missing but will be added as soon as possible.
Download this article in Adobe Acrobat format.Requires Acrobat Reader. (10/9/01).

W1RIL Qualcomm 10 GHz Mods. Ken Schofield, W1RIL, (4/11/95)
Notes & Graphics on 1 watt PA Modifications, Rcvr LNA board,
AC/DC Power Supply, Waveguide/Coax Transition.(Added 10/9/01).

"Modifying the Qualcomm 1W Ku-Band PA for 3.4, 5.7, or 10 GHz",
by Kerry Banke N6IZW. Presented at Microwave Update 2001, Sept 2001,
Download this document in Adobe Acrobat format. Acrobat Reader program
is required. (10/10/01).

Qualcomm +10 Volt Power Supply Module with -5V bias generator and
protection circuit in event of bias failure. (10/10/2001) Schematic drawing
by WA3PTV in Adobe Acrobat format (2/6/2003). Note: these older units
are used to supply power for both the synthesizer circuitry and the 1 watt
Power Amp in many of the amateur transverter conversions. Many reports
have been received of power supply failure due to aging electrolytic caps
in the negative 5 volt bias circuitry. See Suggested Repair Procedures by
WA3PTV and WB6IGP, in Adobe Acrobat format. (Updated 3/8/2004).

TCXO (Crystal Oscillator) Pinouts, descriptions and modifications

Programming Spreadsheets for Qualcomm Synthesizer Boards in
Excel 97 Format

Comb Generator for VHF-Microwave using Qualcomm surplus TCXO
driving single 74AC00 or 74ACT00 IC. Produces 1 ns pulses at 10 MHz
intervals. Good for weak marker signals every 10 MHz. Schematic in
Adobe Acrobat format (.pdf) . By Kerry Banke, N6IZW, May 2001.