Archive for the ‘Uncategorized’ Category
On the Shoulders of Giants
April 11th, 2011 | 
Author: I really can’t believe I was invited to post here on AmateurRadio.com. I tend to be brutally honest and not very politically correct or savvy and I figured it was more likely I’d upset someone here than be invited to post.
I do already have a website (a bit out of date, albeit) and a blog (which I will reserve for lengthy and very technical posts or ones I don’t think are of general interest). But I will try to post here first. Lets make the best of it regardless, shouldn’t we?
Spring is very rough for me in the free time department. I have to “un-winterize” everything and do “honey-dos” and the antenna projects, and then other ham projects/operating which always seems to come last :(. So likely with my other ‘blog, you’ll see more in the winter than in the summer from me!
This weekend was typical Iowa in that the weather was actually very nice, but the threat of very violent weather and actually too strong of winds to do much productive work hurt the schedule a bit– pushed everything out another weekend… sigh…
Anyway, I digress.. I was asked by Matt W1MST to try to have some microwave, 1+ GHz plus material here. I have to be honest, I am a VHF+er by heart and most of my 25 years licensed, but only in the last year did I get decent HF antennas, so lately my interest is in HF and (even though I said I never would) contesting and paper chasing. I figure it’s time I tried it. So if any DX wants to work me or ND (ZERO in the ND QSO party, dudes, what’s up with that? I worked a bunch of rare DX that weekend but no ND? huh?), SD, MN, NV, WY.. e-mail me and set up a sked! 🙂 But I suspect that I’ll post mostly HF stuff for awhile. Help me get WAS and DXCC if you want to see more microwave stuff! (I’m sure VUCC would be next. Like I said “cocaine” would likely be a cheaper hobby!)
But for my first post I’m going to document something not invented by me nor even yet built by me.
Especially in Engineering, good engineers “engineer”, great ones “steal”. There are many “giants” in amateur radio.. the best thing we can do is build on their legacy.
Here is probably the least expensive way to get a couple of watts on 10 GHz. This amplifier was designed and built by Jerry Seefeld, WA9O who builds his own solid state QRO station on VHF/UHF and Microwave– several hundred of watts combined on each band, and runs it from the trunk of his car as a QRO rover! I’m not there and wasn’t when I roved. What can I say.. his stuff is seriously hard core and really, really good…
This is his 10 GHz amplifier: It turns out that the “FET” that is used in the Down East Microwave 10 GHz amp, is really a MMIC and has internal matching in it. The part is available from DEMI currently for $110, the part number is FMM5061VF, it’s a Eudyna (formally Fujitsu Semiconductor) part. It turns out that this device’s width is the same size as the width of two SMA’s mounted close together. Since the device is a MMIC with internal input/output matching, only biasing and simple grounding is needed to complete the amplifier.
With some very careful machining and a breadboarded negative bias circuit, this device can be used without a printed circuit board.
This is the view of the device mounted between two SMAs. Bypassing and grounding of the device is accomplished by “bubbles” in the copper tape and convenient soldering points.
Here is a view of the “top” of the amp:
WA9O 10 GHz Amplifer NO PCB, connector side
Here is a view of the bias circuit schematic. Comments from WA9O on this will be posted at the end of this blog post.
And finally the business side of the amplifier with the bias board installed:
Here are Jerry’s comments about this circuit.
“The P channel IRF9530 has a 27K resistor not labeled in diag. This keeps the IRF9530 turned off when not grounded to xmit. The LT1054 has a voltage divider of two resistors to set the output to -5V. Kinda neat to have something to produce a neg supply and regulate it too. It’s good for 100mA but only 25mA is needed. The LT1085 is a 3 amp unit and if the power is applied by accident with the T/R in xmt then only 3 amps should hit the 5061 until the -5V builds up a milisecond later. It should be Fred-proof. The 5061 draws just under 2 amps regardless of B+ voltage. DEMI runs it at less then my 8.5V and they have been run as high as 10V but I don’t have the guts to run it above 9.0V.“
.
See the “Fred-proof” comment, he must know me. It’s a very simple design… and I posted this for the first AmateurRadio.com post for a reason. First off, Jerry WA9O and I would like to say that all of the old “you can’t do microwave if you can’t machine to the thousandth” was never correct and is even less so with our modern, internally matched, broadband components. (Jerry has told me in the past I could forward on the design of this amplifier if I gave him credit! I’m giving him credit! It’s NEAT! I will build it someday when I get off the HF “high”).
All I can say is that idea, that things had to be built to commercial tolerances to work at microwaves– did more damage to that part of the hobby than anything else possibly could have.. thanks ARRL.
It’s like (exactly) being told you can’t work DX with your HF vertical and crappy ground system, you need a 70′ tower and a beam, so don’t bother with anything less. Well that’s nice but a lousy antenna is infinitely dB better than nothing. In most cases, your best tolerance machine work will work on VHF+ and it will just keep getting better with experience!
In this case, that 10 GHz amp, a DBS/DSS dish and a drilled out feed or a W1GHZ horn will put you into the “big boy league” on 10 GHz for as little as $200 for the amp, nothing for the dish if you are a good dumpster diver like I am, and maybe $300-$400 for a transverter, which, of course you will build yourself, right? And the bragging rights are always fun.. only you and the others who have done it will realize that the equipment is almost easy with modern components. Now working DX at 10 GHz is harder but it’s a really fun challenge and there are others out there who would LOVE to help you do some.
I’d like to encourage microwaves. And IMHO, 10 GHz is where it really becomes fun. There are so many cool things to do on ham radio.. and this is one of the more “cutting edge” aspects of the hobby.
Probably my next post will be another “giant” post (at HF though).. but this one I am building and hopefully will test. Check back here in a week or two for that!
73 de W0FMS
Dayton Hamvention® Survival Guide
The Dayton Hamvention® is the most influential annual gathering of amateur radio enthusiasts in the world. It’s been around since 1952 and for much of that time it has taken place at the Hara Arena, a large multi-purpose facility just outside the city limits of Dayton, Ohio. It’s a three-day event that takes place in the month of May that fills the hotels and campgrounds in the surrounding area to overflowing.
Attendance peaked in the early 1990s at over 33,000 visitors making it easily then the largest ham radio convention on the planet.
Of course, if you just mention to a few of your friends that you’re planning on making the trip to Dayton at least one of them is bound to declare that “Hara Arena is a dilapidated old venue that deserves to be torn down”. While it’s true that the facility has seen its better days, it’s also true that this is a multi-day hobbyist event that attracts tens of thousands of visitors.
April 2011 Buddistick Giveaway Winner
We are very pleased to announce the winner of the
Buddistick Deluxe Package
from Buddipole Antennas
Thanks to Chris from Buddipole for sponsoring this month’s drawing.
We had 1,124 entries!
We’re giving away more great prizes soon.
Stay tuned and get ready to enter.
OK, onto what you’ve all been waiting for!
The winner of our April 2011 prize giveaway is…
FUNcube Dongle on eBay: Going, going…
Are you trying to get your hands on one of those coveted FUNcube Dongle SDRs? Well, it looks like a healthy used market is already emerging on eBay. This seller started the bidding off at $175 — just about what he (or she) paid for it. But with only about 8 5 3 1 hour left to go, there are 4 7 9 10 bids and it’s already up to $217.58 $228.75 $255.51 $270.55! How high will it go? I’d argue that it’s still a terrific value even if it were priced higher.
A tidy little profit and surely a sign that demand for these little gems exceeds supply. There is big opportunity here. Hopefully Howard G6LVB and the good folks at FUNcube will be able to ramp up to meet this demand soon.
What about a US-based distributor? Would the dongle have to be type-accepted to be sold/marketed in the US? Maybe someone with more experience with these this could chime in….
How To Save VHF and UHF Bands in the New World of Wireless
Here in the US, proposed legislation HR 607 recently made headlines as the latest amateur radio band threat, with a bid to reallocate the 70 cm band in the next ten years. ARRL is opposing the legislation on the basis that it would reallocate currently non-commercial spectrum to commercial interests.
On the surface ARRL’s claim is valid. But eventually this approach is going to fall on deaf ears at the FCC and in Congress. Commercial interests holding bands is not inherently evil. But in this current “pro-business” climate, the value of resources are increasing being judged more by revenue potential than benefits to a subset of citizens. Sadly, the “bang-to-buck” ratio that the FCC is getting by continuing to allow amateur radio to use this prime real estate band is abysmal. While the 70 cm band does have numerous repeaters across the US, it seems that in many areas the band is just dead or serves as a life support system for 2m repeater links or cross band repeaters that would otherwise be dead if it weren’t for 2 meters. Even worse, the 2 meter repeaters being linked are often dead as well, other than weekly ARES/RACES nets and the occasional kerchunker.
Since amateur radio can’t generate revenue from spectrum, the default benefit of amateur radio having the spectrum is public service. But when public service is used as a justification for keeping a band allocated to amateur radio, that argument can be easily turned around against amateur radio in the situation of 440 and HR 607. If the band is used for true public service in amateur radio perhaps only one or two times per year per one hundred square miles, and a competing use such as a mobile network in which the general public and public safety agencies can use it continually and use every last hertz, the amateur radio public service argument falls apart. The public overwhelming gets more service from the band in the hands of mobile wireless carriers than amateur radio.
What’s the solution? While mobile wireless networks are spectrum hogs, such technologies today can squeeze 2 or 3 bits per spectrum hertz of data transmission with complex modulation techniques, extensive frequency reuse, and “smart” antennas. Amateur radio needs to upgrade its technology to squeeze more information into the spectrum and use it to transmit information of value. Amateur radio needs to give up on classic single-carrier FM analog repeaters as a mainstay of VHF and UHF communications and migrate to wideband spread-spectrum digital modes and repeaters that carry both voice and data. To some extent this needs to mimic mobile wireless networks, but in an affordable lower tech and “open software” manner. Initially D-STAR comes to mind, but it’s like climbing a tree to get to the moon. It’s still a narrowband mode that can carry only a meager amount of data and lacks the complexity needed in its protocol for technological growth.
The new technology needs to be paired with a decentralized and open messaging system that connects with the Internet and is inter-operable directly with existing messaging standards. This would enable the creation of a true resilient 21st century messaging network, one that would come closer to having the capacity and speed necessary to provide public service benefits in the event of a disaster that would cripple mobile wireless and landline networks.
ARRL and other organizations worldwide need to develop a plan for such a technology and network, get support from manufacturers for low cost hardware, and build a development community around it. There needs to be a road map to show regulatory agencies where we’re going, not where we have been. This is what will save our valuable bands in the new world of wireless.
Win a Buddistick™ Deluxe Package!
AmateurRadio.com & Buddipole Antennas have teamed up to give away a Buddistick™ Deluxe Package to a very lucky ham!
(a 175 USD value!)
Combating Interference: From AC and Antenna
Depending on the type of rig you’re working with, interference from antennas or the AC line are likely degrading signal strength. While U.S. and international Hams face different interference challenges based on their hardware, man-made noise, the electrical grid and more, I wanted to share my experience using a piece of power management equipment typically suited for high-end audio gear. In addition to being a UK-based operator, I’m also an “audiophile,” which led to this experiment.
Recently, I decided to try a power management device designed to provide, component level filtering and protection to any AV system, on my HF transceiver, a top of the range Japan Radio Company JST-245 just to see what effect it had on the noise floor which has been increasing bit by bit every year.
Suffice to say the product lowered the noise floor from a constant S4 to an acceptable S1-S2 on the rigs meter. I was amazed and replaced the standard JRC kettle IEC several times with and without the product in line, and the same results came back every time when the piece was in the chain. My experiment was on 28.535 MHz where I normally work DX on the 10 meters.
These measurements show how dirty the mains are (at least in the UK) since you could actually see the reduction on the rigs meter. It’s worth noting that my AC power is fed through overhead lines, and not underground as with many modern homes, which likely adds interference. But with many UK and international hams lamenting the rising levels of QRM, in my experience, electrical main noise is the biggest culprit.
From what I understand, interference in the U.S. and internationally is driven by the antenna side of the receivers and not through the AC side. I also understand that a high percentage of ham radio transceivers used by hams worldwide have external DC power supplies that are usually well filtered, and wouldn’t require an external AC line filter since they feed the radios directly with 12 -14 volts DC. However, based on this, I’d say any international ham operator with an internal AC power supply (like mine) could benefit from an external power filter.
I know many new radios feature advanced DSP filtering/processing, but hearing the difference this product made inspired me to share my experience. One last cool thing is that the power unit also acts as a under/overvoltage protector which adds a layer of safety while protecting expensive investments from power surges, sags and spikes.
Now, to find a solution for filtering the RF signal before it reaches the radio antenna.
