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K7DAA USA flag USA

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Member of: ARRL / AMSAT / QRP-ARCI (#13072) / FISTS (#15314) / Flying Pigs (#2572) / NAQCC (#4887) / GQRP (#15570)

Note: If you are in the Morgan Hill, San Martin, Gilroy or Hollister areas, please stop by the K7DAA repeater system, sponsored by the Morgan Hill Amateur Radio Society (www.MHARS.org). We operate two completely independent repeaters, each with their own IRLP/Echolink node:

1).  147.33 MHz, with a +600 kHz transmit shift, and the PL is 103.5 Hz.  It is located on one of the two hillsides supporting Anderson Dam at about 925 feet ASL.Its EchoLink ID is K7DAA-R or number 9537, and the IRLP node number is 7588, but the node is off the air for upgrades.  In the interim, please connect to our UHF repeater below.

2).  442.975 MHz, with a +5 MHz transmit shift, and the PL is 100 Hz. Its EchoLink ID is K7DAA-L or number 9536, and the IRLP node number is 7662. Note that this repeater will accept all incoming IRLP connections, but the EchoLink node on this repeater is restricted to known users only, unless you are calling from an RF node, such as another repeater equipped with EchoLink capabilities--the ones with a -L or -R.  If you would like to be able to make incoming connections from your smart phone or computer, please email me and ask to be added to the EchoLink known users list.  We do this to reduce the large number of random incoming EchoLink connections.  This is not meant to be unfriendly or super-exclusive, just preserving bandwidth for our many regular users!

This second repeater is 100% solar-powered, is located at 2100 feet ASL, and is a wide-area design that covers most of the San Francisco Peninsula and the Bay, from parts of downtown San Francisco to as far south as areas of Monterey, Watsonville and Seaside. If you are attending a game at Candlestick Park, you can easily raise the repeater with a handheld on low power!  Due to blockage by the mountain range to the north and east, coverage is quite reduced in the East Bay/Oakland area.

Both repeaters can be linked together, as they are during our weekly net at 9 PM Pacific time every Wednesday.  Please join us via radio if you are local, or via EchoLink using the K7DAA-L connection on the 442.975 MHz repeater.

It's a very relaxed atmosphere, so feel free to chat with anyone you might find there! Although both systems are fully capable of emergency operation, remember that the vast majority of the time--it's not an emergency!

 


 

The picture in the upper right corner actually shows three amateur radio operators! In addition to me, K7DAA, is my wonderful wife Dede, who decided to get a call as close to her husband's as possible--W7DAA! Eric, our younger son in the foreground, is now K7DRN. Behind Eric is David Jr., our older son, who says he feels plenty of family "peer" pressure to get his license now, and is planning to do so very soon! Sam, our golden retriever, would probably like you to know that he is properly licensed as well...

Closeup picture of K7DAA in his shack

Ham radio has been very good to me over the years--providing me with an enjoyable hobby, as well as a springboard into a very fulfilling professional life! I wish you well, and hope that you find it as fun and challenging as I do! Please permit me to tell you a bit about who I am, and what I am:

First, a bit of my ham history:

I grew up in West Covina, California, a suburb of Los Angeles. With the help and encouragement of my elmer, Bob Howard (WA6DLI), I got my novice license (WN6SVQ) at age 10. Upgraded to Technician class a year later. I accidentally let my license lapse while I was out of the country, working as a missionary in Brazil from 1972 to late 1974. When I got back, I studied up for a week, then went down to the Long Beach, CA, FCC field office (no Volunteer Examiner program back then), passed my 13wpm code test, as well as the General and Advanced written tests, all in the same day. I received my new call--WB6VYN--in early 1975.

At the end of 2007 I decided to change my call from WB6VYN to K7DAA, since it fairly closely matches my initials, is much easier and more distinctive to shout at a DX station (I think it's worth an extra 3 dB over a 6 call!), and because I've lived on and off in 7 land.

My present QTH is at the southern edge of Silicon Valley. Morgan Hill is a very pleasant town with a population of about 35,000. It shares its northern border with the much larger city of San Jose, in southern Santa Clara County, and is approximately bisected by US Highway 101. We are about 75 miles south of San Francisco.

I was an Advanced class ham for most of my adult life, then finally decided to make the jump to Extra, mostly to get the additional 25 kHz CW sub-bands on 80. 40, 20, and 15 meters--most of the good DX is down in the bottom end of the band. I passed the Extra (Element 4) test with a score of 100%. I also hold an FCC General Radiotelephone license (was First Class until the FCC combined the First and Second together a few years back). I "aced" that test also--in 1978. That's so long ago that I think I used a slide rule for the test!

I worked for Apple Inc.for 9 years as senior group manager of the Communications Standards & Architecture team. It was a bit like working in Santa's toy shop! We created and developed the directions for Apple's wired and wireless communications technologies that get incorporated into Apple's portable and desktop computers, as well as other fun and interesting things! I retired from Apple in late 2011.

I now have lots of fun as a senior RF hardware engineer, designing wireless technologies at Roku: http://www.roku.com

If you haven't tried a Roku box yet, you really should! It is the future of high-resolution video-over-IP, and presently has over 2,000 free channels, along with the usual Netflix, Hulu, and other pay-type channels. Everything just comes in over your present connection to the Internet...unless you are still on dial-up (really??).

Anyway, I have RF engineering in my blood, and my ham hobby has greatly enriched and provided direction for my professional life.

 


 

I have 10 issued patents so far, with several more still rattling around somewhere in the bowels of the USPTO. Here are several technologies or products of which I am the inventor:

 

  • The 300 MHz SAW oscillator circuit that allows all of us to lock and unlock our cars with small keyfobs, or simply by pressing a button on the key heads.
  • The infamous "I've fallen and I can't get up!" pendants that seniors and the disabled might wear around their necks to signal for help, as well as similar remote control hand-held products (lots and lots of various types of these). Many of these are on 303.875 MHz. Some are also on 418 MHz.
  • The wireless security/duress systems used in, among other places, the Paul Revere home (a US historical landmark) in Boston, MA.
  • A very large number of the 295 to 433.92 MHz wireless smoke alarms, PIR motion detectors, and glass-break detectors used by many of us in our homes or businesses.
  • The Panasonic Gigarange series of 2.4 GHz cordless phones--the first successful use (in 1997) of the ISM 2.4 GHz band by consumer-grade cordless phone products--a huge money-maker for Matsushita Corporation. I, along with 3 other guys (one of which is also a ham!) designed a novel, low-cost spread-spectrum method, as well as the radio subsystems that gave this product its amazing range and performance.
  • The pop-out X-Jack 2.4 GHz antenna system used by US Robotics and 3Com for their wireless LAN and Bluetooth products.
  • A patent I developed at Apple that allows two Wi-Fi or Bluetooth devices to securely sync up with each other by simply bumping or tapping them gently against each other.  This could greatly simplify the secure exchange of money between you and your friend, or could also be used to allow someone to join your home's wireless network.
  • Six other assorted antenna and RF patents, mostly for WLAN and Bluetooth products in use all over the world today.
  • A number of goodies coming as a result of my time at Apple that I can't mention yet!

 

 


 

I'm a member of IEEE Antennas and Propagation, Communications and Microwave societies, and a past voting member of the IEEE 802.11 working group. My name is on several of the 802.11 standards, including 802.11n.

I also sat on the Board of Directors of the Wi-Fi Alliance until the end of 2011, when I left Apple. We're the ones responsible for giving you all of this fun Wi-Fi Internet stuff!

I was involved in developing the original Bluetooth specification, and led one of the 9 original Bluetooth promoter groups while senior director of wireless engineering at 3Com Corp (back when it was a force to be reckoned with in the Ethernet and networking markets).

I have also designed and built a number of ham and commercial VHF and UHF repeaters, remote bases, and Internet control systems. I developed and sold a small number of very sophisticated 65C02-based talking repeater and remote-base controllers for ham groups in the 80's and early 90's. This was before repeater ID's and other functions were commonly announced using voice--something that's pretty much taken for granted now.

I've also written tech articles for 73 and Ham Radio magazines, as well as some smaller-circulation ham newsletters.

In early 2016, I was elected to the Board of Directors of NARCC, the repeater coordinating body for Northern California.

 


 

I'm currently set up for most of the ham satellites, as well as CW, SSB, FM, PSK-31, RTTY, DMR and just about any digital mode on 1.8 through 450 MHz. For HF, I use either Fldigi or DM-780 for the digital modes, along with a RIGBlaster USB Plug-n-Play interface. For satellite operation, I'm usually using one of my MacBook Pro laptops and MacDoppler. It can easily connect to both my FT-847 and my Yaesu G-5500 Az-El rotator, which uses the LVB Tracker's USB interface (In addition to the link to the Amsat store, have a look here for more extensive LVB Tracker info).

I try to keep abreast of new developments, and have also enjoyed experimenting with station remote control over the Internet, VoIP, EchoLink, etc.

When I get really frustrated with my poor location and even poorer antenna systems, I operate via the W7DXX remote HF base in New Mexico. It's fun to experiment with differences in propagation between Northern California and New Mexico, a distance of about 1000 miles southeast of here. Using the Internet, I'm able to operate this system, as well as my own home station, from anywhere on the planet.

CURRENT SHACK RADIOS:

  • Kenwood TS-590 - My most recent purchase.  Has a great receiver on it, and is a pleasure to operate.
  • Yaesu FT-950 - It has roofing filters and IF DSP, but my poor antennas don't allow me take full advantage of all these features.  I like the built-in CW and Voice contest keyers (voice board is an option).
  • Elecraft K2 - a very enjoyable QRP rig to build and operate. I have the 100 watt "lid" as well as the standard QRP (10 to 15 watts) configuration with the internal lead-acid battery that makes it a great portable QRP station.  It only takes two minutes to switch the top lid of the box between the QRP + battery config to the 100 watt config.  Very nice.
  • Yaesu FT-847 - 160m thru 70 cm transceiver. Great for full-duplex satellite work. Wouldn't part with it. In some ways superior to the Kenwood TS-2000, in my humble opinion, especially with the Inrad 8 pole SSB filter installed in place of the stock IF filter.  No VHF/UHF birdies to contend with when working satellites, unlike the TS-2000.
  • Yaesu FT-8800R - Very nice dual-band 146/440 MHz radio. Full duplex and cross-band repeat. It works very well. The only think I don't like about this radio is its fairly cryptic user interface. It's just something you have to learn, then use.  I actually have three of these radios--one for the shack, one in "go box" I'm assembling, and one mounted in my 2015 Plug-In Prius.  For antennas, I use either a Ventenna stealth 146/440 antenna on the roof, or I can also switch in a homebrew 3 element 2 meter quad in the attic that is pointed north. The gain of this beam allows me to be almost full quieting into the Palo Alto N6NFI repeater on 145.23 MHz.
  • Alinco DR-235 - For 1.25 cm FM. Connects to a 4-element homebrew 223 MHz yagi in the attic that I mounted to the rafters with nylon string. I built the yagi with 10 gauge bare copper wire elements on a 26 inch wooden broomstick for a boom. Total cost was about $8.00. Also points north towards the majority of the Silicon Valley repeaters.

PORTABLES:

  • A Kenwood TH-F6 HT. Very nice unit, and the only tri-band rig presently on the market that includes the 220 band with a full 5 watts output. It's my current favorite HT to carry around.
  • Kenwood TH-D72 HT - A $500 does-everything radio with APRS TNC and GPS built-in. Also works full-duplex for FM satellite work.
  • A Yaesu FT-60R HT - This is my "grab-n-go" radio of choice if I'm involved in emergency communications. Very rugged, and you can't beat the fact that it can run all day, with a full 5 watts output, on a set of standard AA-size alkaline batteries. Also probably the easiest radio to program.
  • Yaesu VX-3 - I just bought this one for Dede to throw in her backpack while she is working on her music degree at San Jose State, but she'll have to buy her own now, as I'm really hooked on this tiny little radio! It's only 1.5 watts output on VHF and 1 watt on UHF, but that seems to be plenty, especially for use about Morgan Hill with the K7DAA repeater overlooking the whole Garlic Valley. Just a very well-designed, cute little unit that truly fits in a shirt pocket. The very definition of a "portable" radio in my opinion. By the way, this radio DOES transmit DTMF, even though it does not have a full-size DTMF button pad. That was almost a deal-breaker for me until I found out how to do it.
  • A number of the Chinese handheld radios--Baofeng UV-5, UV-B5, TYT THF-9, etc.  These all work pretty well, especially for the money invested.  You can throw a Baofeng in the glove compartment, along with a spare battery just in case, and you're never without a radio wherever you go.
  • A TYT MD-380 and a Connect Systems CS-580 handhelds for DMR digital modes using the Brandmeister network.  These two radios both also work very well as "normal" analog FM transceivers.

ANTENNA TUNERS/AMPS/MISC:

  • LDG AT-1000Pro auto tuner that handles the tuning for my stealthy loop antenna, and allows me to pump up to 1 KW into it. You have to get used to the sound of this baby tuning, though! It sounds like someone dropping large marbles on a steel box when it's searching for a match. I routinely get "What's that noise??" questions from anyone a room away from my office/shack when it's doing its thing. No matter--it works great.
  • LDG Z-11 Pro auto tuner--works like a champ, even with just a watt or two of drive! Added the internal AA batteries, put it in a plastic Tupperware box, and mounted it at the base of the downspout of my rain gutter system. This allows me to use coax feed directly to this "antenna", and is pretty stealthy.
  • Elecraft T-1 QRP auto tuner--works great also, but much smaller than the LDG tuner.
  • MFJ-948 Versatuner II--some times you just can't beat a good manual tuner!
  • Heil GM-5 dual-element desktop mike
  • Bencher BY-1 Key
  • Palm Mini Paddles for portable keying. Tiny, and I really like their feel. Bought mine from Marshall Emm at MorseX.com. He's a great guy to deal with.
  • The cute little American Morse KK-1 hand key, as well as its brother, the Porta-Paddle (it rides around in the glove box of my car for some mobile CW fun!).
  • Heathkit SB-220 - I like the fact that it proclaims that it's a "2 KW Amp" on its nameplate, even though that's from back in the days when we all measured transmit power by the DC input levels. So it's 2 KW INPUT, and about 1.4 KW OUTPUT. Plenty for my needs! It was very well-constructed and lightly used before I bought it on eBay. Since then, I've completely rebuilt it with new electrolytic capacitors and all of the usual Harbach mods--low-voltage PTT, soft start, new fan, etc. I also added a much beefier Peter Dahl 1.3 Amp continuous-duty high-voltage transformer for added OOMPH! Too bad I can't use it routinely here in this house, but I do use it on "special" occasions (hopefully not when the neighbors are home)! Most of the time, though, I'm using 100 watts or less. Often it's far less--note the QRP stuff below.
  • Ameritron AL-811H 800 watt amp.  I got this almost brand new for $550, so why not!?
  • I have also built the K5OOR QRP amplifier kits: Both the 40 watt HF Packer and the 100 watt Packer Pro amps.

ANTENNAS:

  • Pacific Antennas PAC-12 mini vertical - great little portable antenna.  It's so handy that I have two of them!
  • PAR End-Fedz 20 meter, 40 meter and 40/20/10 QRP multiband end-fed half-wave antennas.  I like 'em.
  • Superantennas MP-1 - neat portable vertical, and very well-made.  Competitor to the PAC-12.
  • Superantennas YP-3 - a three-element portable yagi for 20-6 meters. This is a great Field Day antenna, to say the least. It's a very manageable size without sacrificing much efficiency. You can easily adjust it to any one band you choose in just a few minutes. Put it up 20 or more feet and you've got lots of contacts just waiting to be made!  This has become a popular "go to" antenna for our group's Field Day.  Too bad that it seems to no longer be in production.
  • DX Engineering 5-band Hexx antenna.  Like the YP-3 it is only able to be used for Field Day or semi-portable outings.  Great antenna that also works well with minimum elevation.  We used it as the main antenna for our 20 meter voice station for our 2016 Field Day operation, and didn't lack for contacts all day.  If you are thinking of either the Hexbeam or the YP-3 antenna for Field Day or portable operation, one major advantage that the YP-3 beam has over the Hexbeam is that the YP-3 tucks away into its very nifty 3 foot long padded bag and can be set up quickly.  If I break down the Hexbeam into its shipping box, it will tuck into a car, but with a much longer assembly time due to the need to measure and clamp the six fiberglass spreaders.  It was not made to be a portable antenna, but I'm still considering how I can turn it into one!  One way that might help is to mark all of the spreaders with a permanent marker for both the proper length settings as well as their order of placement into the spreader hub.  I've done that, and it cuts considerable time off of the assembly stage.
  • A couple of homebrew 1/4-wave aluminum verticals. I mount them (temporarily on some weekends) on a 1.25 inch 10-foot copper pipe I drove down into the grass in the back yard. About 10 inches of it protrudes from the ground, making it both a good mounting point, as well as the beginnings of a ground attachment point for the radials I spread out onto the grass.  Now that the trees in our back yards have matured a bit more, I am experimenting with leaving the 20 meter, 16 foot tall vertical standing in the back yard 24/7.  The worst they can do is tell me to take it down, but my neighbors seem to be just fine with it (and me), meaning no TVI, and it's barely visible.  So far so good.
  • High Sierra Sidekick - screwdriver antenna with extended stinger mounted at ground level. I've experimented with it, but don't routinely use it. It doesn't seem to be very efficient compared to my others (strictly in a non-mobile setting). As time goes by, I'll try some different experiments with it and its big brother, the HS-1800/Pro. Those of us that live in CC&R-land will try anything to get a decent signal out!
  • Sometimes, when I get really desperate, I even end-load my aluminum rain gutter on 40, 80 and 160, too! Works surprisingly well, but fairly noisy on receive, and it favors the south and west--not great when you live on the West Coast. Hey, at least Hawaii's no problem!  I had a very fun contact on my rain gutter with a homebrew 2-watt QRP rig on 40 meters a couple of years ago.  It was SKN (ARRL Straight Key Nite), and I had a nice CW QSO with a guy in Redmond, WA.  He couldn't believe I was only 2 watts on a rain gutter!  He even asked for a repeat, just to make sure!
  • Magnetic Loops:  I've also been experimenting with very small HF loops made with copper pipe. So far, I've been very pleased with the results. I may mount a 1-meter diameter model in the attic for 30 through 10 meters when I finish perfecting the remote tuning motor drive for its tuning capacitor. It's very efficient, and really gets out well. I had 5-watt 17 meter SSB contacts with both the east coast and Hawaii within 30 minutes on the first day I finished building it--mounted about 6 inches above ground! Both ops were running 400-500 watts, and both gave me 5-7 to 5-9 signal reports.
  • For satellite work, I'm using a homebrew 11 element 436 MHz yagi, and another homebrew 6 element 2 meter yagi. Great antennas, but I'm working on redesigning them for circular polarization. Not always pleased with the polarization fades I'm getting at times on FO-29.

MOBILES:

I used to have a section here on how happy I'd been with an FT-857D, ALS-500M amplifier, and a Lil' Tarheel HP antenna on my 2001 Camry.  Four wonderful years of high-power mobile operation!  Worked lots of DX with it.  Then a woman in her 20's had a moment's inattention on the 85 freeway coming home from work one evening, and smashed into the rear of my car.  The good news was that there was no injury to anyone, not even my ham gear.  Bad news was that the car was a total loss.  Now I have a 2015 Prius Plug-In that allows me to drive in the left-hand HOV lane in rush hour!  No way I can operate HF mobile due to the very high RF noise coming from the Prius, but my commutes are much quicker and annoyance-free.  It seems perfectly happy with my FT-8800 on VHF and UHF, so it's a compromise.  But...I'll miss my Camry ham station!

QRP:

I absolutely love building and operating little radios!  "Little" usually means QRP (5 watts output or less), portable, and battery-powered.  I have buiilt or bought so many that I can't mention all of them here, but please do consider building and operating something yourself.  You may find that you get hooked on these little guys, just like me.  When someone asks me what my favorite QRP radio is, I usually have to say that it depends on what the intended usage will be.  For the absolute best combination of size, weight, and performance, I would probably say that the KX-1 is my favorite.  If I'm going to be stuck on a desert island with only one radio, I would take either the FT-817 or the Elecraft K-2 (see above--love its super built-in memory keyer, and it also has the built-in antenna tuner option for those random wire slopers tied to palm trees!).  My sentimental favorite, and also just about the lightest weight of all is the SW-40.  I've had more fun on 40 CW with that little guy than any other.  Anyway, here is a partial list of QRP rigs I always like to talk about:

  • Oak Hills Research OHR-500, as well as the fine DD-1 digital dial, and the excellent WM-2 analog QRP wattmeter, all from Marshall at MorseX.com.  The OHR-500 has been retired, but the single-band OHR-100 kits are also a very good choice.  Marshall also has a large selection of awesome straight keys and keyer paddles to choose from.  Tell him I said "howdy" when you call!
  • Elecraft KX1--Neat little handheld QRP rig that puts out about 1.5 to 4 watts on 80, 40, 30 and 20 meters.
  • Yaesu FT-817ND - Excellent portable HF/VHF/UHF all-band rig. Great for QRP and satellite QSO's. I think that this radio is almost perfect, given its size. I find it amazing that Yaesu managed to pack so many features into such a small rig. I might buy another for full-duplex portable operation on the SSB/CW satellites. I think I'll need to grow another arm to do this effectively, though--one to hold the Arrow antenna at the sat, one to tune the receiver, and another to tune the transmitter for doppler compensation. Oh, wait--I guess I'll need a fourth arm to hold and key the mike! I'll have to think a bit more about this first...

It also seems that I have a growing number of little QRP homebrew transceivers popping up in the shack and on the workbench. This is definitely a fun part of the ham radio experience. Nothing like building your own gear and being thrilled to see it working! In addition to the OHR-500 and the KX-1 above, these are just some of the many kits I've enjoyed building and operating:

  • Rock-Mite 500 mW fixed-frequency direct conversion transceivers for 20, 30, and 40 meters from Small Wonder Labs. You can still buy one of these at QRPme.com.  Many other neat items for sale there, too.
  • KD1JV's neat little ATS-3B. A six-band, 5 watt CW rig that fits in an Altoids tin!
  • The Small Wonder Labs SW-40 - it's a tunable 40 meter 2.5 Watt CW transceiver.  The brainchild of  K1SWL, unfortunately now out of production (but I still have one more unbuilt one!).
  • The PFR-3 portable, trail-friendly, self-contained transceiver from Doug at: QRPKits.com
  • BitX20A 20 meter CW/SSB rig, also from Doug at: QRPKits BitX20A page
  • The MMR-40 7 MHz CW/SSB transceiver: QRPKits MMR-40 page
  • One each of the NorCal QRP club's 2N2 transceiver family for 40, 30 and 20 meters (now retired kits)
  • For the experimenter, W8DIZ has some great do-it-yourself radio modules and parts that you can wire up together.

 


 

So...

My biggest challenge these days, ham radio-wise, is to find a decent enough HF antenna system to satisfy my need for DX, given the confines of my typical postage-stamp Bay Area lot and a handful of neighborhood CC&R's.

Any of you living on large lots with lots of open space for your antennas should definitely understand my envy and admiration!

72 and 73,

Dave

www.k7daa.com

8573076 Last modified: 2018-01-11 00:43:37, 30150 bytes

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