Mike KI5YX brought in a 220 J-Pole made with 3/8 in copper pipe (2/3 the length of a 2M J-Pole). The ‘U’ at the bottom was about 13 in tall, and the half wave radiator above was around 26 inches. There used to be a 220 Net on one of the 220 repeaters, but not lately.
The slightly revised meeting format allows a brief Show and Tell from each person prior to the Tech subject program. Mike held up the copper J-Pole and the rest of us had a few comments. A common concern on antennas was the advertised gain figures, often distorted by ISOTROPIC gain; ground reflection gain, or plain lies. Next mtg is on Lincoln’s BDay, Febr. 12th.
Tune in Wed and Fri on the B.A. 146.91 repeater at 7PM for the Conspiracy Net where you can talk on a variety of subjects.
Mike KI5YX: Really? That old? Tom KJ5NMH: Yeah, we weren’t even teenagers yet when this one was new. 1958. Tube finals, a 6146 driver and 6550 final, both laid down horizontal in the aluminum heat sink in back. International doesn’t make crystals any more so I added a freq synthsizer, you can see it under my fingers at the top, and a PL tone generator too. It’s also there, but so small you can’t see it in the picture. Ten (10) channels now. Big problem is there’s no hi/low power switch so it’s a hundred (110 W) and ten Watts out all the time. It’ll smoke your average mobile antenna. I got another one from the 60s that’s all transistor. Put a freq synthesizer in it too, but totally different than this one. Has a two wire serial input to the crystal socket from outside with a digital freq display.
Next mtg is 4th Thurs at Scott’s hamburgers in downtown Bixby. More on how antennas work (input impedances) and what controls gain (G5RV and OCFed not included).
Right as you went in the door at the Henryetta Hamfest Saturday, Jason W5HP had this nice looking Yaesu 950 HF and 6M rig for which he was asking $500, not much more than a new Xiegu G90 that doesn’t have even a quarter as many buttons and knobs and runs only 20W.
Some other interesting items included a gold plated D-104 microphone (they also had a regular chrome D-104). There was also a Yaesu 991A put back in the box marked 1 kilobuck. Wonder if you could get it for less.
They had a whole box of Vibroplex paddles. You could probably buy one and then suggest to friends that you know code really well. (Change the subject really quick after that.)
They had 28 tables and not all of them were in use. With increasing awareness and growing Ham population in the Tulsa area, this one is going to get more popular, and it’s only 42 miles from Bixby.
The Henryetta club website is (Crossroads club) CARCradio dot org.
Larry W5LQF answered the most Jeopardy game questions Thursday night and took home a 1995 Radio Amateur’s Handbook prize. Sam KJ5BJR came in 2nd and won the 1972 edition (which has a bunch of Vacuum Tube specs in the appendix). Questions (or answers) included What’s the ARL callsign, W1AW, and What’s the color code for a (very conservative) 33k resistor, Orange Orange Orange. Note: Sam BJR and XYL Debbie K5DBE brought with them a new 10W H/T and 50W dual band radio they’d won at the TARC Christmas meeting two days before.
Kenny EKW’s Kenwood 7400 2M rig puts out 28W on high and 5W low power. Internal dissipation (Volts x Amps less RF output) changes from 38 Watts to 37 Watts (i. e. It gets just as hot on low power as it does on high.) We measured both input Volts and Amps and RF output Watts of an old Kenwood G-707 dual band to find it uses just over 5 Amps at full 27 Watts out on 2M, and also 5+ Amps putting out 22 Watts on UHF (and also the smae 5 Amps with only 14 Watts out on 462.5625 (that’s FRS Ch 1). No, we’re not going to use it there, just checking. At lower power levels it gets much less efficient, like a 2 Amp draw at 3W out.
Note: This Tx efficiency thing is not just some esoteric bit of information, but real life physics of like, How Many Watt Hours do I need to run my Yaesu 857 at 15 Watts of FT8 mode for six hours at 25% duty cycle in a portable operation (battery powered). Answ: A lot more than 15% of 20A (full power) with those parameters.
Before the digital rigs (mid to late 1980s and 90s) an HF rig in receive mode might use half an Amp or less. The early Kenwood 520 (had 73 transistors) with the tube heaters turned off (there was a switch to do just that) ran only 340 mA in Rx mode. My digital Kenwood 440 with a hundred memories and general coverage receiver takes 1600 mA in receive. That heavily impacts efficiency if you’re thinking POTA this weekend with a LifePo battery, and reducing power output to only 15W of FT8 mode doesn’t save as much as you’d think. Put these specs on paper (FM or 100% duty cycle mode): 100W uses 17.5 A, 50W uses 12 A, 25W takes 9.5 A, and 10W still takes 6.5 Amps. You could subtract the 2.4 A at zero output to get exact Tx efficiency, but you get the idea, a quarter of full output (17.5A) takes over half as much battery power. (Figure your duty cycle, maybe 10 to 20 % and the number of hours you want to work. Note: A brief stint might be accomplished with a much smaller LifePo than those car battery size hundred Ampere hour things bc you can use them down to near zero without severe damage, unlike a lead acid.)
Heisenberg, Schrodinger and Ohm are in a car. They get pulled over. Heisenberg is driving and the cop asks him, “Do you know how fast you were going?”
“No, but I know exactly where I am” Heisenberg replies. The cop says, “You were doing 55 in a 35.” Heisenberg throws up his hands and shouts, “Great! Now I’m lost!”
The cop thinks this is suspicious and orders him to pop open the trunk. He checks it out and says, “Do you know you have a dead cat back here?”
“We do now, darn you!” shouts Schrodinger. The cop moves to arrest them. Ohm resists.
Earl WB5UUW from Broken Arrow, brought in this key component of an All Band Rotary Spark morse code transmitter from the WWI era, a motor driven spark gap. Together with a huge power supply (takes 2 men and a boy to lift), CW key, and aerial wires connected to the two spark posts shown, it’ll run about 10 kW and allow you to make contacts perhaps hundreds of miles distant on a good night. (You caught the part about being an All Band transmitter.)
Parker W1YG recreated a tube type Hartley Oscillator single tube transmitter as used in the 1920s and we had several pics of it at the meeting. Using a sine wave oscillator on a single frequency meant that several guys could get on the air without interfering with each other, a big improvement over wide band spark transmitters.
We also inspected an hourly chart of a 100Ah LifePo battery charging voltage. LifePos both charge and discharge in the range of 13.0 to 13.5 V which should make your 12V rig very happy. Charging is 99% complete at 13.6 V so it’s possible to use a charger meant for lead acid batteries (typically ending at 13.8 to 14V) and not have to buy a separate (and expensive) charger specific to LifePos (which usually have an internal Battery Management System that CUTS OFF if you try to charge them much over 14.4).
Rich ZQG recently bought a Palomar Engineers OCF 4010 antenna and showed the SWR chart for several bands. It wasn’t as good as claimed (usable on Every Band 40 thru 6M) probably because it’s only up 15 ft with one end drooping down to 5 ft the last 20 ft of antenna. More later. Here’s the more: Got it up 8 ft at the ends, but still only 15′ at the 4:1 balun. Tunes real good (low SWR on 40 and 15) and OK on 20 and 10, tunable or even straight through at like, 2.1 SWR or a little more. Chart says it’s supposed to be OK on the WARC bands (30, 17, and 12M) but you really need a tuner there. Six (6M) meters (SWR 2.7) is usable with a tuner.
Matt Damon starred in the movie The Martian, and was rescued partly due to a spaceship returning from Mars using a SlingShot Orbit around Earth to go back and pick him up. We discussed various orbital parameters and requirements, noting the Space Shuttle uses only 2 stages, solid boosters and the shuttle itself with an Enourmous fuel tank (as opposed to the conventional 3 stage rocket) to attain orbital velocity. See you at the next meeting 11 December. (4th Thurs canx bc Thanksgiving)
It takes about 35 Ah of battery power to run a hundred Watt rig for 24 hrs at Field Day. That’s most of the ‘usable’ capacity (50%) of a 100 Ah lead acid battery, but only 35 of those new hundred Ah LifePo batteries, and you can buy those used on EBay for just over $100. (LifePo batts are good for thousands of cycles over 10 years so you’re unlikely to wear out a used one.)
Another nice item to have overnight at FDay is a battery powered light. Again, EBay has some nice rechargeable table lamps for around twenty bucks. They’ll run for hours and charge with a phone charger type cable. (Two for $40. Let the XYL have one in the living room. Oh yeah, and that’s how you sell the idea to her, lights on when the power goes out.)
LifePos aren’t the ones that catch fire and blow up. That’s Lithium Ion like your phone, that living room light above, and Teslas. LifePos may fail, but they usually don’t catch fire and don’t emit clouds of toxic smoke. Also, the 12V one as above remain in the 13 to 13.5 range almost their entire discharge curve, so your rig will put out normal full power unlike with a lead acid that gets into the elevens half way down.
Hey, uh, what’s with that pic above? Is it done, like, with mirrors?
A hundred years ago most Hams had transitioned from Spark transmitters to the new Vacuum Tubes which, through Feedback, were able to generate just a single frequency output thus allowing more than one guy at a time to transmit without having to decipher the slightly different tonal quality of a spark to determine who it was transmitting. (The ‘T’ part of the RST signal reporting system.) Tubes allowed amplification of weak signals, and with the recently invented superheterodyne receiver system, up to and over 100 dB of receiver total gain by changing (heterodyning) the frequency of the signal several times.
Transistors (William Shockley at Bell Labs in 1947) allowed the same kind of amplification advantage without all the heat and high voltages that make tubes work. They didn’t take over right away, portable AM radio receivers in the 1950s, and some functions like the Noise Blanker in the Galaxy V five band transceiver in 1964, but by the early 1970s the Kenwood 520 five band HF transceiver had 73 of them, everything but the 12BY7 driver and two S-2001 final tubes (similar to the thirty five Watt 6146 tube).
Transistors are little, and it’s really hard to make 2 batches of them come out with same specs so the gain of a specific type can vary a lot. Example: hFE gain of a 2N2222 runs from 100 to 300. If the batch comes out really bad they call ’em 2N2221s with a gain of 40 to 120.
Differential amplifiers consist of 2 transistors (facing each other) and are really useful, a favourite circuit used in power supplies comparing half the 12V output to a 6V Zener regulating diode. It’s best when the 2 transistors have similar gains so (now) the differential is part of an Integrated Circuit IC where ALL the transistors come out with the Same Range of Gain (and the differential is thus balanced).
Transistors are still little when they handle lots of Amps, but they put them in different cases to get rid of all the heat. The 2N2222 can only handle milliwatts, or up to Half A Watt if you’re bold. The same chip in a larger (TO-5) case is called a 2N2219 and runs a maximum of 0.8 Watts. The Astron favourite 2N3771 comes in a diamond shape TO-3 case that (when well attached to a big piece of aluminum) can handle well over a hundred Watts. Calculate how an Astron 35 running at max with 21 Volts input and 14 out, divides the heat among only 4 transistors. Seven Volts across the transistors (21 minus 14) times the 35 Amps equals, uh, two hundred plus, exactly 245 Watts. Divided among the 4 transistors it’s 61 Watts or so, well within the 150 Watt rating each. Note: The Astron 35 says it’ll do 15 or 20 Amps continuous. No, it won’t. It doesn’t have a fan. Prop up a little five inch computer fan in back of it and you can do that, like, for repeater use.
We won’t meet again until 2nd Thursday in November, the 13th, so there’s plenty of time to go home and look in the back of our power supplies to see if it’s 2N3771s like on an Astron, or something else. The switcher power supplies use an even more expensive type, but you have to open the case to see what kind they are. (They run at like, 40 kc or more into a ferrite transformer, not just responding to 120 cycle ripple.)
DETAIL: The pic shows right side of an Astron 50. It’s covered, both sides and back, with heat sinks. What’s the Date Code on the 3771 (YrWk). So how old is that 50?
According to some, QST magazine used to use the abbreviation MC for Morse Code until one day the kid they had in the print room dropped one of the page blocks, spilling most of the type on the floor. He got it all back together, but wasn’t a Ham at the time and put those two letters back in upside down and backwards so that it read ‘CW’. The powers that be, not wanting to admit a headquarters mistake, (and good at finding words to fit seemingly unrelated letters) came up with the electronic sounding Continuous Wave (Yeah, everybody knows Morse is not continuous.) and that’s how it’s been since. Trivia Q. What year did they start printing QST. Was it 1907, 1915, 1926, or 1935.
Using a freq counter to measure several newish Chinese H/Ts and one decades old Yaesu VX-5 H/T, they were all 150 to 200 cyles high from 146.52 Simplex. (146.520150) We thus concluded the calibrated freq counter was probably off about 150 to 200 cycles at 2M (one part per million or .0001%) The MFJ SWR Analyzer, itself about a decade old (and not since calibrated) was way off showing all the equipment over 1 kc low. Did you know an MFJ has a built in freq counter?
We got a little history of transistors, invented by Dr William Shockley and others in 1947. Xistor type numbers begin with 2N because there are two (2) junctions. Similarly, diodes start with 1N with only one PN junction. The type 2N2222 not only has a great number but also is a good substitute for many other types. You can use two of them to make a QRP transmitter (look up Tuna Two) on 40M that only runs a couple hundred milliwatts. Type 2N2219 is the same exact thing in a slightly larger (higher power) case. Answ: DeForest invented the Audion amplifying tube in 1907. Superhet radio receiver system started about 1926, and by 1935 superhet receivers were about as good as today.
Mark KJ5JVV brought his five hundred dollar Fluke model 177 meter and verified our previous readings on a 100 Ah LifePo made with our seven dollar Harbor Freight digital meters, having found our place between the arches in the center of town and the Bixby Police antenna (see pic above) and then went across the street to Scott’s hamburgers on the North side of Dawes St, verifying that the LifePo was down to 13.15 Volts as a result of being hooked up to a Yaesu 991 for a day and a half trying to see how long the 100Ah would last (13.15 suggests it’s down to under 30%).
Note: Sentence above will not be entered in the Bulwer – Lytton contest for run on introductory sentences. It’s just practice.
Excluding a 57 yr old analog and a faded red Harbor Freight digital with visibly changing readings, all the meters we had (a Fluke and several Hbr/Frts) had voltage readings spanning just a 0.7 % range with the Fluke reading centered in that range (so we can expect a reading of 14.4 on a fully charged LifePo to be accurate). The 11 mA current measurements ranged 3% with Mark JVV’s Fluke 177 way off, nearly 30% low at 9.21 mA. We surmised the cause was a previous owner greatly exceeding the 400 mA stated max range which damaged the internal shunt (and likely the reason Mark got the great bargain. Hey Mark, when measuring mA with that meter, figure it’s 30% low).
The other measurements, a fifty year old 1k resistor with a gold band (that’d aged up to 1090) and the 122 Volt AC line voltage, all came out within a percent – great considering Harbor Freight says they’re only accurate to 1 pt 2 percent. The Hbr/Frts jumped around on the 120 AC while the Fluke seemed to show an ‘average’ reading that didn’t jump around so much.
ADDENDUM: Kenny KJ5EKW offered his Fluke 117 (which he uses professionally measuring black, white, and green wires) and it verified the 11mA current reading that our used $500 Fluke model 177 had erroneously suggested was 9.21 mA.
Radio Society of Greater Bixby 