Archive for the ‘10368 MHz’ Tag
This is our third consecutive appearance at the Bay Area MF, and continues my theme of showing how some ham radio operators continue the tradition of “teaching, mentoring, making, modifying, repairing and improving” radio and radio-related technology. Read my post about ham radio and the Maker movement.
Today’s ham radio operators have an incredible amount of exotic surplus material that can be converted into everyday use on the ham radio bands. Grandpa certainly never heard of surface-mount technology, talking on homemade 47 GHz transmitter-receiver systems or pocket-sized, satellite navigation systems (GPS). But he sure did mentor, make, modify, repair and improve the equipment in his bedroom radio station…..
Not Your Grandpa’s Ham Radio – Maker Faire 2014 Team
Wayne Yoshida KH6WZ
Dennis Kidder W6DQ
Brian Yee W6BY
Marty Woll N6VI
More information on the Maker Faire Bay area.
Here is a gallery of our booth posters for the 2014 Bay Area Maker Faire. More photos, videos and stories will follow. . . . .
This past weekend, some of the active San Bernardino Microwave Society (SBMS) gathered at Fairview Park in the early morning to perform a field test of their microwave systems. Since I did not do anything with my rigs this past year, I decided to skip this field test, and take some pictures of any new more interesting rigs for this contest season.
Here are some pictures of the various station equipment SBMS club members built and tested that day . . .
A post-Tune Up Party party and BBQ was held at Dennis W6DQ’s house. It was nice to relax and visit with the other SBMS members and enjoy some great BBQ chicken….. In the picture below, Walt, WALT explains one of his radio wave demonstrations to a captive audience… Watching and learning, from left to right are Bill Preston, KZ3G; Dan Slater, AG6HF and wife Sandy Slater; Walt, and Jason Sogolow, W6IEE.
If you are curious about the test setup, here is an article written by Kerry Banke, N6IZW, with some small edits by me:
Checking Microwave Radio Performance with a Simple ERP/MDS Test Unit
By Kerry Banke, N6IZW (Edited by Wayne Yoshida, KH6WZ)
Before heading for the hills with 10 GHz equipment around contest time, members of the San Diego Microwave Group (SDMG) and the San Bernardino Microwave Society (SBMS) check the Effective Radiated Power (ERP, transmit) and Minimum Discernible Signal (MDS, receive) with the simple setup described in this article. We hold the test sessions at the June and July meetings in preparation for the ARRL 10 GHz and Up Contest in August and September. The advantage to having two sessions is that it provides a second opportunity to verify improvements or allow participation if the first session is missed. The test unit works with both wide band and narrow-band radios.
The Pole-Mounted Test Setup
The setup consists of a pole mounted X-Band converter unit connected by coax to a signal source (for MDS) and an amplifier/power meter located near the radios to be tested some 200-300 feet away. The MDS test must be performed first to align the radio antennas with that of the converter. A signal generator is connected to the IF coax and a suitable frequency (145 MHz) and power level (-40 dBm set to transmit an easily detectable carrier around 10368 MHz at the output of the converter.
MDS for Receive
Each participant adjusts their equipment and the system antenna for maximum signal as the power level of the signal generator is reduced to the point where it is no longer detectable by the radios. The level at which the signal can just be detected is considered the MDS.
ERP for Transmit
The ERP measurement is performed by connecting the IF coax to the amplifier and power meter. Each radio transmits one at a time and the power meter reading recorded. The variable attenuator is adjusted to keep the reading in a suitable power range for the power meter and amplifier. For the amplifier used, the maximum output power was about +10 dBm and the power meter range is about –20 to + 10 dBm so the attenuator was adjusted to keep the reading in the –20 to 0 dBm range.
The choice of the IF frequency for the converter depends on what is available for a 10 GHz local oscillator but needs to be low enough to keep the losses reasonable through hundreds of feet of coax. The amplifier gain and maximum output need to be based on the power meter characteristics. The signal generator needs to match the IF frequency chosen, have suitable stability for CW work (NB only), and have variable output (may be an external attenuator).
The converter consists of a Frequency West Brick as a 10,223 MHz local oscillator for a mixer used as an upconverter for MDS and down converter for ERP. The converter has a 13 dB horn antenna connected to the mixer RF port. Power is supplied by a 12V battery on the ground with a DC/DC converter supplying the required voltage for the local oscillator. The coax used is 300 feet of RG-59 which was readily available. No attempt to correct matching losses for the 75 ohm coax has been made. The loss of the coax and mixer as well as the amplifier gain was measured at the operating frequencies. It is not really necessary if only relative measurements are to be performed but it does allow a good comparison between measured and calculated values.
The results of the test are entered into a spreadsheet, which then calculates the ERP based on dish size in inches and estimated PA output of the radio under test. The distance in feet from the radios to the converter is input to the sheet, which then calculates the path loss in dB. For ERP, the sheet provides calculated ERP, measured ERP and the difference between them. For MDS at this time, only the signal generator level is recorded and is used for relative measurements.
Block diagrams for the 10 GHz and 24 GHz units are described in the PDFs below:
10 GHz ERP-MDS Block Diagram
24 GHz ERP – MDS Block Diagram
Intro to the MDS/ERP Event Results
(From an entry on the SBMS website on August 10, 2012)
These spreadsheets show the results of workshops/picnics where amateur microwave stations were compared on a unique test range for both transmitting and receiving performance. The test setup was developed by Kerry Banke, N6IZW and has been used by the San Diego Microwave Group (SDMG) and the San Bernardino Microwave Society (SBMS) over the past few years. The test setup consists of a remote TX/RX transmitter/sensor unit installed on a pole about 15 ft. high at a distance of approximately 220 ft. from the stations being tested.
The remote transmitter produces a stable signal on the operating frequency, such as 10368 MHz. Operators tune this in with their rigs and peak their antennas. The signal is then reduced in level until barely discernible (MDS). That level is logged. The operator then transmits with maximum CW power and the RX sensor power level is logged. The spreadsheet is used with the logged data and with data on each rigs claimed antenna size and transmit power to allow comparison of measured versus expected performance.
The results have been useful, not from an absolute basis, but by allowing operators to compare their rig’s results against other amateur’s rigs having similar TX, RX, and antenna characteristics. Any major performance differences between systems can help focus on problems that can be solved before upcoming contest events.
In past events, operators have discovered problems with relays, cables, connectors and even non-functioning power supplies.
Interpreting Results
Receive (MDS) performance is shown in the column marked “MDS Gen dBm.” You want the largest negative value compared to other stations having the same size or performance antenna on that frequency band.
In the last column marked “Meas-Calc,” transmit ERP performance is shown. A zero means that the ERP came out exactly as expected given the claimed transmitter power and antenna gain. A positive number indicates an ERP that is better than expected by that many dB. A negative number indicates system performance measures worse than expected.
Here are some results over the past years – 2013 results added!
TuneUp2013
SDMG ERP-MDS-2013 Results
TuneUp-2012
TuneUp-2011
TuneUp-2010
TuneUp-2009
Tune-Up-2008
TuneUp-2007
TuneUp-2006
TuneUp-2005
TuneUp-2004
TuneUp-2003
TuneUp-2002
TuneUp-2001
TuneUp-2000
The ARRL 10GHz and Up contests are coming up soon (August 17 to 18 and September 21 to 22), so I thought I’d re-publish my article that originally appeared in The Proceedings of Microwave Update 2005.
The Harris-Farinon Model SD-108175 / 076-108687-001 solid state power amplifier (SSPA) has been seen globally on the surplus market over the last few years. This amplifier is a part of a large rack of equipment running on the traditional 24VDC, positive ground telecom power system bus.
In its original form, the amplifier is very robust and heavy, since it is rated for continuous duty, Class A operation. Figure 1 shows the unit as received. It is mostly heatsink, and the RF unit, where the microwaves are amplified, is the tiny silver box on top.
The SSPA unit (Model SD-108175) measures about 15-1/2 inches wide, 4-1/4 inches high and 10 inches deep, and weighs over 15 pounds. The little silver box (part number 076-108687-001) with SMA isolators at the input and output, is about 3 inches wide, 1 inch high and 2-1/2 inches deep.
Important: Be careful if you see these units for sale, I have seen some inaccurate descriptions of these units – for ham radio use, the only item we want is just the amplifier (076-108687-001) and not the heatsink/chassis assembly or the power supply DC-DC converter.
Figure 1. The Harris-Farinon 10GHz amplifier is very beefy, but it is mostly heatsink. The little silver box is where the RF is amplified.
I took the unit to Dave Glawson’s lab (WA6CGR) to see if we could integrate this SSPA into my X-band rig. It is a 1W unit, but I have several that put out as much as 3W on 10368 MHz. I purchased several of these units at a very reasonable price, and am pleased with their performance on the 10 GHz Amateur Radio band.
The terminals on the amplifier as well as the power supply PCB are marked, simplifying some of the guesswork about what-goes-where. The amplifier includes a “POWER MON” SMA female jack, which should probably be capped with a 50Ohm termination to prevent oscillations or weird things from happening while the amplifier is operating. A “DET OUT” pin is useful to verify amplifier operation.
It may be prudent to read Chuck Houghton’s article, “Above and Beyond, Microwave Stripline Retuning Procedures” on tweaking circuits before any “poking around” is done on any SHF amplifier, to prevent damage. Links to references are at the end of this article.
The first step is to power it up and verify operation in its “as-is” state. With about +17dBm (about 60mW) input, power output is about +35dBm, or a little over 3W at 10368MHz. Current consumption is about 2.6A during standby and about 3A at 10V with RF applied. Dave and I wondered whether or not we could tweak the amplifier to get more power out, so we took a look under the lid of the little silver box, see Figure 2. We decided not to tweak anything inside the tiny box.
Figure 2. A peek inside the SSPA. No tuning is required to get two to three watts output on 10368MHz.
Since the amplifier passed its first tests, the next step is to re-package the unit so it would be more suitable for portable and roving operations. Certainly, a weight reduction could be done by shrinking the size of the RF module heatsink, and adding a fan or two.
Since the amplifier passed its first tests, the next step is to re-package the unit so it would be more suitable for portable and roving operations. Certainly, a weight reduction could be done by shrinking the size of the RF module heatsink, and adding a fan or two.
The DC-DC Converter
The original power supply board appears in Figure 3. A casual inspection of the unit showed that the 24V input was buck-regulated down to 12V, and then further reduced to minus 2.1V for the bias and +10V for each stage in the amplifier. The DC-DC power supply looks like it can be modified and re-used, by applying 12VDC where the brick converter has its output. However, this modification was not attempted.
Figure 3. The DC-DC supply board. A 24V to 12V brick converter is mounted to a 14-1/4 inch by 7-1/4 inch heatsink under the PCB. The existing DC-DC converter may possibly be modified to make the unit work on 12VDC input. See text.
I thought a better, lighter, more modern power supply could be built fairly easily, and the large heatsink for the power supply could be deleted.
With Dave’s help, I made a simple DC-DC converter using a Linear Technology LT-1083 adjustable regulator and a few resistors for the +10V supply. The negative bias supply was made from a surplus 99-cent DC-DC converter. I built the power converters into separate chassis boxes, since I had them on-hand. A single box is also acceptable.
Like all FET power amplifiers, one must make sure that the minus (gate) bias supply is always connected before the supply voltage to prevent damage to the devices. I am sure there are several solutions for power-on sequencing to prevent this from happening, including relay or other switching or timing schemes. However, I chose a very simple route: I simply wired the minus voltage directly to the amplifier bias feed-thru capacitor, with no switching in-between. The plus 10V supply line is switched to the amplifier via a power relay, actuated by the sequencer. This way, whenever the rig is powered up, the minus bias voltage is “automatically” applied (it was never off in the first place), and the plus 10V is applied only when the rig is put into transmit mode.
I had a pair of 24V brushless DC motor fans in the junk box, so I am using these to blow on the heatsink. Since I have both 24V and 12V running around in my rig, I wired up a two-speed fan control using a pair of spare relay contacts. When the radio is in the receive mode, 12V is applied to the fans, reducing the noise. When the rig goes into transmit mode, 24V is applied to the fans, running them at full speed.
The final result is shown below. The amplifier is mounted in one of my 10GHz rigs, “Ms. June.” 3 The SSPA puts out 2W at the antenna port, and now measures about 4 inches by 7 inches by 1-1/2 inches, including the cooling fans. A re-labeled, surplus CB panel meter (1mA movement) connected to the DET OUT pin indicates SSPA operation. (Update: Ms. June was cannibalized for parts. However, many of her parts were used in other radios, including my latest, record-setting 10GHz transverter.)
Figure 4. The Farinon SSPA installed in “Ms. June,” one of my early 10GHz rigs. Two watts appears at the waveguide port at the antenna relay in transmit. The DC-DC converters are enclosed in separate chassis boxes, and can be seen just to the right of the amplifier. A re-labeled surplus meter monitors amplifier operation.
References
1 – “Above and Beyond, Microwave Stripline Retuning Procedures,” by C. L. Houghton, WB6IGP, San Diego Microwave Group:
http://www.nitehawk.com/rasmit/mstrp_tu.html
2 – The surplus TDK DC-DC converter is described as a “5V in +/-5V DC/DC converter” at MPJA Online, as part number 1042518. This unit is under a “closeout” deal, so supplies may be limited. Go to http://www.mpja.com, and look under “Power Supplies,” “DC-DC Converters.” Their phone number is 800-652-6733, 9AM to 5PM Eastern Time, Monday through Friday. Although probably not necessary, I removed the TO-220 device from the board and re-mounted it to the metal chassis box for heat-sinking.
3 – Most of the SBMS members have names for their rigs, mainly because, as many of you know, microwave radios tend to have personalities of their own. Ms. June is my sixth 10GHz radio re-build. “Morpheus” was my first attempt, see CQ magazine for December 2003 and January 2004 for my dubious start on the microwave bands.
wayneyoshidakh6wz 