Conversations with Ed Bigbie - December 5th 2008

(This story came from a private blog I started some time ago called "Conversations with Ed Bigbie". I started this journal because I've always felt so enlightened and enriched by our discussions and I knew that one day Ed would be gone so I wanted to create something to hold on to from the man I have admired and learned so much. Sadly, that moment came yesterday when Mr. Ed left this world to join his wife in Heaven. I have been rereading some of those postings and thought others might enjoy and remember Ed the way I do.)

I had the very distinct pleasure this morning of enjoying a long breakfast and enlightening conversation with my very dear friend and electronic engineering mentor, Mr. Ed Bigbie.

Ed is well known in the Amateur Radio community by his callsign, W4MMQ. He is an Extra Class license holder and received his first license in 1946. Actually his amateur radio license is probably the least of his credentials. He is a registered professional electronics engineer, a FCC licensed First Class Broadcast Engineer and a member of the IEEE, among many other fine distinctions. He is the retired owner of Savannah Communications in Garden City. The family-owned company is now run by his talented son Don Bigbie.

One day I will write more about Mr. Ed’s vast experiences in radio and television and his many contributions to Savannah, GA broadcasting but that will have to wait for now.

This conversation is one of several recently where Mr. Ed and I discussed his past venture in the design and building of a premium balanced antenna matching unit that he built and sold beginning in about 1996. Antennas and antenna matching has become one of our favorite discussion topics. Ed knows a lot about many technical topics but he is especially knowledgeable about antenna matching.

So, after we ordered our toast and omelets and overpriced espresso coffee drinks we settled into a quite corner at Scoops coffee shop in Richmond Hill. I’d picked Ed up at his home a few minutes earlier and noticed he was clutching a brown manila envelope and a 1967 World Radio Laboratory catalog. My good manners prevented me from blurting out, "What’s in the envelope” before he was ready to share but I knew he had brought along something special – as he so often did.

First he gently turned the pages of a perfect specimen of an 1967 WRL amateur radio catalog. Those of you old enough to remember WRL already know what this was like -- really nothing to compare with a present day Ham Radio Outlet catalog or an AES catalog. The first apparent difference was that everything on every page was manufactured in the United States! Even today I still drool over those fine Hammerland receivers, radios by Hallicrafters and R.L. Drake and Collins. It was a pleasant trip down memory lane back to the time I was a young boy and looked at this same catalog!

Next Ed opened the envelope and began to take out pictures, one by one. The first image was of a somewhat younger Ed; in 1996 in his very well appointed amateur station in Helen, GA. You can be sure that Ed either owned, or previously owned any piece of amateur radio equipment that he has ever wanted. In this particular picture I saw what looked like the most recent Icom premium amateur radio transceiver. Over his left shoulder I could make out an ETO linear amplifier which alone cost more than the sum total of all the amateur radio equipment I have ever owned! Just to the left of the ETO was a stack of three very rugged looking boxes that were the subject of this conversation.
The one on the bottom was the prototype of a very professionally finished balanced antenna matching units that Ed had designed and built.

As I said earlier, Ed knows RF engineering better than anyone I have ever known. I am continually amazed by the cadre of engineers he has been personally acquainted with. (Just for starters, he and Louis Varney G5RV of the legendary antenna were best of friends. Add to that list Art Collins, of Collins Radio; Bill Hallagen, founder of Hallicrafters, and others, and it is easy to appreciate the wisdom and experience that Mr. Ed brings to these conversations.)

It seems that Ed was also a longtime friend with Walt Maxwell (W2DU) – maker of the famous “true current balun” Walt was an engineer with RCA at the RCA Space Lab. There, while he had access to his employer’s very well equipped RF testing facility, he begin to experiment on a new antenna matching unit.

Ed told of his visits with Walt at the RCA Antenna Lab and test range in March 1970. W2DU, for whatever reason, never had any commercial aspirations for bringing his “new” tuner to the market so as time passed his design notes lay filed away.

But Ed was quick to recognize the classic simplicity and value of W2DU’s simple tuner and if Walt wasn’t going to build them then Ed resolved that he would.

So using two rugged 28uH roller inductors and a massive 3.5 kV variable capacitor Ed constructed his prototype W4MMQ Balanced Matching Unit. He labeled it serial number 1. (You can read Ed’s construction notes elsewhere on this blog).
That unit is still in service today, says Ed. “AD4RO (William B. Greer) has it. It’s on the air every morning up in Johnson City Tennessee”.

It is important to remember that these are balanced line tuners. There is no provision for a coaxial output. Because they tune a balanced line, there are two identical roller inductors mounted side by side. The one of the left is driven by a rugged crank reminiscent of those I’ve seen on AM broadcast transmitters. The second parallel roller inductor, mounted just a couple of inches to the right of the first inductor is driven with a special cogged belt so that one crank on the front panel drivers both inductors.

Ed was able to locate a small parts company in Florida who manufactured the drive belts and sprockets. The third component, from left to right across the heavy aluminum chassis was a 500 pf capacitor. Other than a unique true current balun, which Ed assembled, that’s about all there was to it. Most manufacturers insert a voltage balun on the output side but this has a current balun on the input side

But these tuners were not meant to be decorated with lots of bells and whistles, they were meant to run day in and out, handle high power and whatever antenna mismatch most anyone would ever encounter.

Over the next few years Ed and his friend Gene Rhodes of Deland, Fl manufactured quite a number of these “built like a tank” antenna matching units (please don’t call it a tuner, Ed corrected). And being the kind and generous man that he was, they are all in the homes of other hams. He never kept one for himself.

After about the third refill on coffee (Ed did not drink coffee which may account, in part, for his excellent health and longevity) I expressed an interest in documenting and publishing the construction details and even envisioned that he might lead the Coastal Amateur Radio Society club members in a group construction project.

Ed must have anticipated my interest because he then presented me with the remaining contents of the manila envelop which contained his hand drawn schematic, a typewritten essay and a fist full of photographs of the tuner from all angles.

I’ve published his work elsewhere on this blog for all to enjoy. Some months later I heard Ed mention that he had been contacted by a number of amateur operators from all over the world seeking information about building their own tuner from his notes. I could tell that this pleased Ed very much and I was glad that I’d helped to bring him just a small bit of recognition for his efforts.

The breakfast crowd had long cleared from Scoops. A few people we both knew drifted over to our table to greet Mr. Ed. Unrushed, we both got up and I drove slowly back to Strathy Hall savoring every moment of our conversation and not wanting the visit to end. It was a Friday – my day off from the office. I parked in Ed’s driveway where we continued to sit and talk for the longest time.

Our conversations would frequently drift to discussions of broadcasting and RF engineering which I enjoy most. It was that shared interest in broadcasting, particularly AM broadcasting, that first brought Ed and I together sitting in a booth at Captain Joe’s Restaurant down in Midway, GA in 1980 when he made a cold-call on Coastal Electric offering his company's services to maintain our newly purchased Motorola radio system. Interestedly much of that equipment is still on the air, 29 years later, and we've never signed a subsequent agreement. With Ed it was possible to conduct business solely on a handshake. We never had any problems but we knew that if we did it would be Ed's integrity that would resolve the conflict, not words in a contract.

I don't know of anyone else right now that I would trust to that same extent.

Finally, we wound down and parted company. I returned home feeling enriched and enlightened once more from another memorable conversation with Ed Bigbie.

Ed Bigbie - Silent Key

It was with much sadness today that I learned of the passing of Mr. Ed Bigbie (W4MMQ) of Richmond Hill, GA.

Ed was a very kind and generous man and he was a best friend and mentor to me in the field of amateur radio and electronics for the 29 years that I have known him.

Ed Bigbie received his Amateur License in 1946. He has been a member of ARRL since 1946 and QCWA since 1975. He received his First Class Phone License with Radar Endorsement in 1945 and has been an ARRL Technical Specialist since 1996. Ed was a Senior Member of the Institute of Radio Engineers (IRE) until it merged with The American Institute of Electrical Engineers (AIEE) and became the Institute of Electrical and Electronics Engineers (IEEE). Ed was a Senior member of IEEE and a Senior Member of The Society of Broadcast Engineers (SBE). He was also a charter member of the Association of Communication Technicians (ACT). Ed had been a Registered Professional Engineer (PE) in the State of Georgia since 1965 and authored several articles on antennas, transmission lines and matching units.

You could frequently find him on 3.995 early every morning where he put out a "broadcast quality" signal from two IC-756 PROIII's, a IC-PW1 amplifier and an 811H amplifier.

The W4MMQ Legacy Balanced Antenna Tuner

By E. F. Bigbie, PE

Why a balanced antenna matching unit?

Everyone calls them tuners, including the manufacturers. But they don’t tune, they match. For this article I will call it a tuner; however it is actually an impedance matcher. It is used to cancel reactance, both inductance (+j) and capacitive (-j).

Antenna tuners are much like shovels. It takes more than one kind of shovel to perform a variety of jobs efficiently. For example, a snow shovel isn’t suitable for digging holes in hard ground. A tiling spade could be used to shovel snow, but it wouldn’t be very efficient. Similarly, no antenna tuner circuit can do every antenna-matching job extremely well.

A balanced-load tuner should be designed from the ground up for the job that it is intended to perform. This article describes a circuit that does a superb job of feeding an open-wire transmission line such as ladder line or window line. It cannot be used for unbalanced loads such as coaxial transmission line or for end-fed antennas.

Now that we have so many bands below 30 MHz, an open wire-line center-fed wire antenna systems looks even more attractive than it did when such antennas first came into popular use in the 1930s. Taking advantage of this versatile antenna system requires a box that will interface the 50 ohm unbalanced output of today’s transceivers to the highly variable impedance (Z) of the balanced feed points of multiband antennas.

Many makers of antenna tuners claim their circuits can operate into an unbalanced load or a balanced load such as ladder line. Actually most of the contemporary “matches everything, balanced or unbalanced” antenna-tuner circuits produce a semi-balanced output when used with a balanced load. Although the antenna will radiate in this situation, a semi-balanced output is like having a semi-balanced checking account. It is less than wonderful.

A look at the schematics for the contemporary “matches everything” antenna tuner circuits reveals they are usually unbalanced, high-pass-filter-characteristic, T networks with a voltage balun hooked to their unbalanced outputs. This is a compromise performance when used with a balanced load.

The imbalance in these “balanced” tuners can be easily confirmed with an RF voltmeter or RF ammeter(s). The actual current or voltage at each output terminal is progressively more imbalanced above 7 MHz. At 28 MHz, it is not uncommon to have 50% more current or voltage in one of the legs than in the other leg.

Some may ask, “Why not use the same balanced tuner design that was popular in the 1930s?” As many old-timers know, the 1930s-era balanced tuner consisted of a resonant (or near resonant) center link coupled tank circuit with moveable taps on the secondary. For each band change, the taps had to be moved and reopitmized, the total inductance changed and the tuning capacitor retuned. Changing bands was labor intensive! These tuners were seldom built in enclosures, because near-constant access to the taps and the inductor(s) was a necessity for changing frequency. It was a common practice to build these tuners on a breadboard for maximum accessibility.

In the 1950s, the E.F. Johnson Company marketed its Matchbox series of balanced antenna tuners. These tuners used the same center-link coupling arrangements as the earlier tuners but they eliminated the movable-tap arrangement by using a double differential capacitive voltage divider across the tank inductor. (A differential capacitor is the RF equivalent of a potentiometer dc-voltage divider.) This allowed the operator to increase and decrease the voltage fed to the antenna electrically, without changing taps. The Johnson circuit worked, but the Z-matching range was severely limited. Frequently, the SWR could not be reduced to a satisfactory low level.

The balanced tuner described in this article has two front-panel adjustments, a turns counter that turns two roller inductors that is connected together with two pulleys and a timing belt and a high voltage capacitor. It uses the rarely seen balanced version of the familiar unbalanced L network. Changing bands is a piece of cake with this tuner and the matching range can be made very wide using enough L and C to handle the job

The 1:1 current balun solves the capacitive imbalance problem of the 4:1 voltage baluns used in the output side of conventional tuners. The bottom line: high impedance baluns are a very likely source of grief no matter how carefully they are engineered and constructed.

All of these problems are easily avoided. The solution is simple – don’t put the balun in the highest-impedance part of the circuit. Instead, put the balun in the lowest-impedance party of the circuit (in most cases, the lowest-impedance part of the circuit is the 50 ohm coax input to the antenna tuner), and build a balanced L-network tuner for the balanced output of the low impedance balun.

So, why have we been putting the balun in the wrong part of the circuit for all these years?

Good question.

Building a no-grief 1.8 to 30 MHz 50 ohm balun is easy. You can build a Walt Maxwell W2DU type choke balun. Use 12 inches of 50 ohm Teflon coax cable and 50 ferrite beads, now available in kit form from the Wireman.

The balanced network consists of two 20 or 28 uH roller inductors connected together with a miniature timing belt and two pulleys, a counter dial and 40 to 500 pF 3.5 kV Variable capacitor, and a 50 ohm current balun on the input side.

See the pictures of the outside and inside of the balanced matching unit for the layout of the parts.





I will give all credit for what I have learned about the Balanced Matching Unit to my friend Walt Maxwell, W2DU. Walt is the author of the book Reflections and I recommend the book. It should be in every ham shack.

About the author:
Ed Bigbie received his Amateur License in 1946. He has been a member of ARRL since 1946 and QCWA since 1975. He received his First Class Phone License with Radar Endorsement in 1945 and has been an ARRL Technical Specialist since 1996. Ed was a Senior Member of the Institute of Radio Engineers (IRE) until it merged with The American Institute of Electrical Engineers (AIEE) and became the Institute of Electrical and Electronics Engineers (IEEE). Ed is currently a Senior member of IEEE and a Senior member of The Society of Broadcast Engineers (SBE). He is also a charter member of the Association of Communication Technicians (ACT). Ed has been a Registered Professional Engineer (PE) in the State of Georgia since 1965 and has authored several articles on antennas, transmission lines and matching units. He runs two IC-756PROIII, a IC-PW1 amplifier and an 811H amplifier. You can find him on 3.995 every morning from 4:00 AM to 7:00 AM Eastern time and occasioanlly on CQ100. Listen on 3.995.


Parts for a balanced antenna matching unit

The miniature timing belts and pulleys are available from Small Parts, Inc. 6901 NE Third Ave, P O Box 381737, Miami, FL 33238-1736 Phone (305) 751-0856
Air roller inductor $60.00 each $120.00
High Voltage Variable Capacitor $70.00
Turns Counter $70.00
1:1 Choke Balun Kit $28.00
Binding posts 2 ea. $6.00
Tuning knob with plate $10.00
Cabinet $75.00

Total $409.00

RF Power Issues with the 857D

Readers of this blog know that I love this little radio. It's the first "new" HF radio I've ever owned. I've always had older tube rigs so understandably I've been quite proud to own and operate this little gem of a solid state compact radio.

It has been fun to drill down into the menus and to occasionally discover a few of it's undocumented features. One interesting thing I noticed, early on, were momentary high power "spikes" when using the rig on low power - this may not be an issue when running the rig at 100 Watts output on CW and SSB.

The ARRL and other reviews of this rig didn't show a problem, yet speaking with other users and doing numerous Google searches suggests many FT857 and FT897 transceivers also suffer from this issue. In the case of my transceiver the effect seems most noticeable in the mid HF frequency bands and is present on CW, SSB and AM. For those who use AM, the spike can be horrific and exceeds 100 Watts out when the microphone PTT is first pressed. SSB doesn't fare any better with spikes occurring on the first syllable spoken after a pause. The spikes on SSB exceed 100 Watts when the power level is set to 10 or 20 Watts.

If you are a frequent reader of this blog you know that I lost the finals in my 857D a while back when transmitting thru a solid state amplifier on 2 meters. I have since been searching for a reason as to why that failure may have occured. I'm still afraid to use the amplifier again until I am more assured as to what happened.

A Gooogle search of my problem led me to a most excellent website, Dave's Astronomy Page http://www.astromag.co.uk/ . I don't know Dave and have not asked his permission to republish and otherwise plagiarize his excellent research but I trust he will not be offended that what follows is actually his work.

Dave's concerns over this "power spike" were for the welfare of his linear amplifier.

Running the FT857 "barefoot" doesn't give any indications on the front panel of a problem, and indeed in many cases there isn't an issue with doubling your power for the first 5 milliseconds on transmit. This can be a serious issue when using the FT857 to drive other equipment, such as a linear amplifier. Fortunately, Dave says, his Acom 1000 linear is rated to cope with spikes of up to 100 ms duration, and these are less than that. Users of other types of amplifier may damage their equipment.

Examples of the first CW character being sent are shown below, the power output setting was 20 Watts on the 7 MHz band.

The only cure found so far is to feed a fixed voltage of between -3.0 and -3.5 Volts into the ALC socket of the FT857. Using a fixed ALC voltage still allows the power output to be set correctly from the menu in the FT857, it is also beneficial in taming the SSB spikes without causing problems to normal speech peaks.

Not all bands produce the same results, the spikes were at their worst in the mid HF bands and almost non existent on 2m. Dave says his oscilloscope is not capable of working at 432 MHz, do he doesn't comment on that band.

From experimentation, feeding what appears to be a reasonable voltage level on one band can reduce the power output on another band to near zero. This indicates that setting the voltage could be quite critical. I haven't tried the transceiver at widely differing case temperatures, nor have I tried any other transceivers to see if using the voltage my transceiver works well with also has the same effect on a another 857.

Quoting from Dave's website: The test circuit I used is shown below. Using a 9 volt alkaline battery is not a good choice as the maximum voltage required is only -4 Volts. The output (tip and sleeve) are wired to a 3.5mm jack plug, which is inserted into the ALC input socket on the FT857D. The 1.5 K Ohm series resistor avoids shorting the battery out when inserting the jack plug into the transceiver. For longer term use 3 or 4 AA sized alkaline batteries would be a more sensible source of the voltage. Note the FT857D manual gives an ALC input range between 0 and -4 Volts in the specifications. The optimum ALC voltage feed on my transceiver was -3.1 Volts, this level still allowed full output on 2 meters. A setting of -3.6 volts worked well on HF and 6 metres, but killed the output completely on 2 meters.

A more elegant solution is to generate a negative voltage by the use of an NE555, as shown below (note the 47 uF capacitor across the zener was incorrectly shown in an earlier diagram). A 13.8 volt supply is available from the "linear" socket on the FT857. Be careful when wiring a mini DIN plug as they are quite small and tricky to solder without creating a short. Covering the rear of the pins with hot melt glue after soldering the wires helps keep everything secure and short free - the plastic glue can be peeled off for re-work without difficulty. The photo of the completed box also has a phono socket connected to the TX ground pin of the mini DIN plug to give a feed to my Acom linear.

Dave says he contacted Yaesu for their view on this problem and they apparently have a key click modification that is applied to the current FT857D series, from board 07 onwards.

Anyone wishing to modify their FT857 using the modification below does so at their own risk. While the modification was supplied by Yaesu, it doesn't make it easy to implement. The modification can be downloaded here .

The central part of the underside of the main board in an FT857D is shown below (not modified).

How to decode Yaesu serial numbers

If you need to know exactly when your Yaesu radio was manufactured here is the way to decode Yaesu serial numbers:

Position 1 = year made

Position 2 = month made

C = January
D = February
E = March
F = April
G = May
H = June
I = July
J = August
K = September
L = October
M = November
N = December

Pos 3 &/or 4 = lot number(s)

Pos 5<-8 sequence in that lot

Position 1: last digit of the year in which the radio was produced

Position 2: Determine the position of the letter in the alphabet (C=3,D=4,E=5, etc) and then subtract 2. The result gives the month in which the radio was manufactured. Note that the letters will range from C (January) throughN (December). Thus, a radio with a serial number of 5H221234 would have been manufactured in 2005 (5), during the month of June (H=8, 8 minus 2 = 6, June is the 6th month), was part of lot 22, and was the 1234th radio in that lot.

Monitoring the Gulf Coast Hurricane Net

One of the more interesting aspects of amateur radio for me has always been monitoring the Gulf Coast Hurricane Net when there was a storm threatening the Gulf Coast area. As of Saturday evening, the net is active on the following frequencies:

Central Gulf Coast Hurricane Net
Daytime Tactical: 7.285 Mhz
Nighttime Tactical: 3.873 Mhz

Daytime Health and Welfare: 7.290 Mhz
Nighttime Health and Welfare: 3.935 Mhz

Tracking down the elusive electrical noise in my home

I have finally found the annoying “mystery noise” I’ve been hearing on HF (mostly 75 meters) today. I first begin to hear the noise after I moved my Yaseu 857D from my outdoor (not air conditioned) ham shack to the comforts of a spare room in my home. While it is great to have the space (and air conditioning) I immediately began to hear a crescendo of noises that sounded like “birdies” or raspy “carrier like” noises. In one case the noise appeared every 100 KHz pretty much from the broadcast band to 10 meters!

I first had to determine if the noises were radiated signals or were, instead, internal “birdies” sometimes heard from receivers of poor design The way I did this was to switch the 857 to dummy load and verify I could still hear the noise – I still heard it even though it was somewhat weak.

The next step was to determine if it was an internal “birdie” from the 857 or a radiated signal. By disconnecting the HF antenna all of the noise disappeared so I was pretty sure it was not a birdie.

At this point I became convinced the source of the noise was something electrical inside my home. I powered up the 857 from a couple of AGM batteries and tuned the VFO to a spot where I could hear the noise quite loud. I then went to my power switchbox and tripped the main breaker.

What do you know – the noise went away! In fact, I’ve never heard the band so quiet!

After I turned the main breaker back on it was just a matter of tripping the individual breakers until I found the offending circuit. Turns out the noisy circuit was one feeding one of those “touch lamps” – the kind where you touch the metal lamp base and the bulb steps thru three levels of brightness. Those things are awful noise generators! I unplugged the lamp, put the breaker back on and listened to verify the noise was gone. Thankfully it was. But, then I heard yet a different noise which I quickly tracked down to a horizontal sweep signal from the TV upstairs.

That was easy to fix -- just turn off the TV.

But wait – I was hearing yet another raspy noise on the frequency. This one was a little harder to find but it was definitely man made inasmuch as it appeared on even frequency multiples across the band. I suspected the source to be a switching power supply, perhaps my UPS or maybe even the laptop computer itself. It took a while to pin it down but when I unplugged the laptop charger the noise went away – and resumed when the charger was again connected to the computer. It didn’t matter which end was unplugged, the AC supply end or the DC cable at the computer.

So, now I am finally happy. I have found the offending noise and those I can’t eliminate at least I know what to turn off should I want to listen to the same spot on the dial where these local oscillations are occurring.

In most cases it would not even matter but this morning the touch lamp was just tearing up the Georgia Cracker Net on 3.995 MHz and that is what got me started. I would have probably just written it off as a distant carrier on the band but because I was able to listen to my friend Lyndy’s Brannon’s station via his streaming audio setup I knew it was not affecting the entire net – It had to be something local.