Archive for the ‘waveguide’ Tag

Microwave Radio Tune Up Party in Costa Mesa   Leave a comment

028-wayne yoshida-microwave radio

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.

KH6WZ tune up and KH6WZ-5 050

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!


SDMG ERP-MDS-2013 Results














A Christmas Party, the Lytro Camera and a Coupe Goof   Leave a comment

The San Bernardino Microwave Society (SBMS) had a Christmas party this past weekend, and it was a good break from doing sheet aluminum work. The event seemed smaller this year, several of the usual suspects were not able to make it. There was lots of food to share and gifts to exchange. Happily, regular guests Mel WA6JBD and his better half, Tisza KI6DBR came and brought their usual homemade treats, including Tisza’s famous chocolate truffles, microwave dish cookies and a chocolate sculpture. This year’s sculpture was a 10GHz horn and a section of waveguide. And yes, they really do work at 10GHz. Mel measured the return loss of the horn and waveguide and reports more than 17dB or something like that – pretty respectable for an edible 10GHz antenna.

Here are some pictures of the event. . .

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Where else but a ham radio Christmas party would one find a 10GHz horn and waveguide made of chocolate – that actually works

Tisza's homemade chocolate truffles - Yum!

Tisza’s homemade chocolate truffles – Yum!

kh6wz 011

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Gift exchange crowd

Gift exchange crowd

What in the World is That?

After the party wound down, I stayed to get a closer look at Dennis’ new camera. It does not look anything like a camera, but it really shouldn’t because it makes images in a whole new way and enables a whole new way to enjoy still images. I thought it looked more like a kid’s kaleidoscope, rather than a camera.

The camera and lens system optics look very simple. And that is one of the points: You do not need fancy telephoto or macro lens capability. It is done in software.  There are no fancy controls or buttons, only soft pads on the rubberized parts of the case. There is a power switch, a zoom control and a shutter release. An LCD with touch screen is on the back. Here are some pictures of this new gadget.



The Lytro camera. At left is the lens cover, it attaches magnetically. That's an item that will be lost immediately. Center, the camera, showing the front glass and lens. Right - a tripod adaptor.

The Lytro camera. At left is the lens cover, it attaches magnetically. That’s an item that will be lost immediately. Center, the camera, showing the front glass and lens. Right – a tripod adaptor.

As I mentioned on my LinkedIn update, the Lytro camera introduces a paradigm shift in the way we can look at still pictures (pun intended, sorry). At first, I thought this camera simply used some sort of image processing to “fix” images, simple things like contrast and color adjustments and maybe some image manipulation, like PhotoShop. But then Dennis said that you can change focus and “raw image” features, like zooming in – after the image is stored on your computer.

The images are not jpg or other familiar formats – but then – these are not ordinary images, either. You can actually change the depth-of-field – change the point of view of the image.

Watching some of the demos on the Lytros website made me think of scenes from the TV show “CSI:” because you can see an image captured by the camera, and you can actually zoom and move around the various places on the image, and see what else the camera captured.

Visit the Lytro website, pictures and demos and details are worth closer examination. Unfortunately, I don’t have any Lytro images to share – yet.

The Coupe Goof

The day after the party, I went back to work on the Coupe. Something bothered me as I looked at the images and some postings of other builders. The driver’s side footbox and the front, where the pedal box mounts, looked different than mine. And I found another driver side footbox front panel in my box of aluminum parts. I looked at the part number of the “extra” footbox front (15312) on the packing slip, and noticed the description: “Driver Footbox Front Wall, Coupe Wilwood Pedals.”

Argh. Since I have the Complete Kit, it came with a Wilwood pedal box. Part of the confusion is the way Factory Five Racing packed the sheet aluminum – the major parts are held in place on the chassis and are shipped in place. This would be fine for the builders using a donor Mustang pedal box, the “Basic Kit” version.

So, I had to remove the driver side footbox front panel and replace it with the proper one. The good news is that I had all these things in place with Cleco fasteners, not rivets and silicone. And, I used the old panel as a drilling guide for the new panel. Now I have a spare sheet of aluminum I can use for – something. Hatch covers, maybe.

On the left is the wrong driver side footbox front panel. This is the one that is shipped in place on the chassis. The one on the right is the front panel for the Wilwood pedal box. Good thing I didn't silicone and rivet that panel!

On the left is the wrong driver side footbox front panel. This is the one that is shipped in place on the chassis. The one on the right is the front panel for the Wilwood pedal box. Good thing I didn’t silicone and rivet that panel!

Disaster averted - the wrong footbox front panel was removed and replaced with the correct front panel for the Wilwood pedal box.

Disaster averted – the wrong footbox front panel was removed and replaced with the correct front panel for the Wilwood pedal box.