Canare BCP-C4F 75 Ohm BNC Connectors Box of 86 connectors. $65 shipped CONUS
You can email me for payment info. tom @ (this domain )
If you’re reading this- they’re still for sale.
My winter build is underway. A few weeks in and I have it mostly framed up. 88 inch wingspan, 30cc motor and probably 13 to 15 pounds. Cutting and shaping all the wood is pure Zen relaxation.
Thanks for all the comments and questions. I’m happy some people are reading this!!. You can email me email@example.com This site/blog is done in WordPress and hosted by Godaddy.
This is a new antenna I invented. At the lower frequencies it acts like a fat monopole, and at higher frequencies it’s a tapered slot antenna. it shows a very nice SWR below 2:1 from 150MHz to 10GHz. Of course I didn’t invent either type, but I’m positive I’m the first to combine them into one antenna.
Below are pics of a 12DBi helical. I made the helix support from laser cut lexan. The first 1/4 turn feed transition was the critical part in tuning.
Below are more variations of the tapered slot / fat mono. The one in large blue foam is an extended low frequency model. With the larger ground plane and copper tape “top-hat” it’s now usable to 70MHz.
For my Ham Radio HF station I made my 4:1 top mounted balun for my Off-Center-Fed Windam antenna. The core is a 240-77 ferrite, wound with teflon wire. Should be good to 1000 watts.
I was thinking about installing a 3S lipo in my Taranis. The optimistic thought was besides longer run time, maybe there could possibly be a teeny tiny increase in output power resulting from a sloppy regulator that allowed more voltage to the RF board.
BAAAAAAA!!! Wrong answer Hans!
On the bench with a lab-grade 10A variable power supply showed different. I ran this test 3 different times with different bandwidth settings, and different antenna orientations, and it’s repeatable and constant. The RF circuit seems to be more efficient when the radio DC power is at a lower voltage. Running at 12VDC shows almost 0.5 dB decrease in RF output power as opposed to 7.2VDC. Maybe it means nothing, maybe it’s just my radio… what’s half a db between friends, I found later that at 12volts, there is about twice as much ripple and noise (.06v) on the rf board voltage compared to 9volt input. One of the universal truths in radio design…Poor power supply=poor RF.
The next issue is notable. You see 3 different color traces in the plot below. The Orange trace shows a baseline output plot from the Taranis with no audio playing. The Yellow is a plot while audio wave files like – low rates, high rates, gear up, ect were playing constantly at full volume. The Aqua trace is the RF output while music is played at full volume. There seems to be about a 1.5dB decrease in power while loud audio is playing. Again, I aint sayin’ nuthin… Just thinking about power supply current shortcomings. I’m going to re-do this test after I record some constant-tone wave files.
Lastly below, for edumatainment purposes, and not just for X9D owners, I did a plot of antenna polarity coupling to show the importance of never pointing your antennas at each other. Think of the co-pol as both antennas pointing straight up, then laying ONE down 45 degrees sideways, then 90 degrees sideways, then finally pointing each antenna end-to-end. You’re losing 13dB by doing that. That means your 100 mW signal is now 5 mW, and you STILL have to calculate the distance path loss to that faaarrr away model. It’s brown short time.
I was working at the bench and heard a crunch under my bigass workboot. I accidently stepped on a receiver that must have fallen off the bench and cracked the cover off. Oh well good opportunity to check out the innards. Looks like it survived just fine.
A combination of bad soldering joints, and my opening the case too much and disturbing wires resulted in failure of the aileron pot wires. The pics show overwicking of solder on the red wire (indicated by the kink), which made it very inflexible. Upon opening the dust cover, I also found the brown wire detached. Last pic shows the repair.
Just to set this straight… This is the greatest radio since Marconi asked “Can you hear me now?” Since the beautiful Hedy Lamarr said “Jam THIS!” This is an RC transmitter that has every switch and function user assignable, almost unlimited mixes, and plays music while some sexy fembot announces receiver signal strength, lipo voltage, and GPS coordinates !!! The audio hum was hardly there. I had to hold the radio within 12″ to hear it. It didn’t even bug me, but everyone was talking about it. It’s like you live somewhere for years and one day your wife points out the stain on the ceiling… Jeeez thanks! Well I had the tools and figured what the hell. I have the “B” model, and it already had the “Scott’s Special Speaker Mod”
I didn’t fall off the turnip truck yesterday….. That happened weeks ago, and as a paid RF noise chaser I had some clues. The hum changed on how you held the radio. It also changed with antenna position. When I opened the radio, the hum was VERY variable according to which wires and ribbons were moved. That led me to believe there is/was a lot of RFI noise inductive coupled into the whole wire harness. Usually I find that the noise is from DC/DC switching converters. Next in line is the processor clock. That’s what I found on the Taranis. The inter-board ribbons were pretty hot with EMI from 160MHz to 600MHz. The CPU clock frequency RFI has sub-harmonics like a big ugly comb generator response. These harmonics get into the DC bias lines, and pollute all the op-amps and audio amp chips. Even though they’re in the micro volt level, they get amplified up with the audio signals you want.
Since I don’t have a schematic, I didn’t want to do a lot of probing and testing to find where to install filter caps and inline induction. That would cost millions of dollars and government forms would have to be filled out. A simple, quick way of reducing the transfer of RFI between system boards seemed like an easy try. Noise is born on the processor mainboard, and I want to strangle it on it’s way to other boards.
For some fun I display a sample from the “big box o’ ferrites” EMI arsenal. Rings, clamp-ons, beads, plates, tape. Actually the plates are an idea I had in mind to epoxy on the bottom of the boards, and/or to fit and position between the boards when the case is closed. The smallest beads could work, but I’d have to disassemble the ribbon connectors to get them on. I decided on the ferrite tape. I fount the hottest ribbons and gave them a few wraps of ferrite. The probe is so sensitive that I could isolate the two noisiest wires from the ribbon and just wrap those. The ferrite tape seemed to absorb a good amount of RFI, and the noise reduction from one end to the other was about 15dB The audio hum was so reduced that I had to hold the radio at my ear to even acknowledge it.
Please click on the pics for the full view. I show the EMI response before and after, some pics of how I wrapped the ferrite tape around the ribbon cable, and a pic of my DIY near-field EMI probe. The description and diagram of the probe and be found here. http://www.compliance-club.com/archive/old_archive/010327.html
After a couple days of test, I finalized and improved . The tighter the ferrite tape is against the wires- the better. I re-wrapped them and tied it up with waxed lacing string.
Even though the tape mfg claims surface resistivity in the MegOhm range I also put a square of foam over the board so it wouldn’t rub against it when the case is closed.
I found out this also reduced the headphone hum.
Here’s the ferrite tape fitting. The upper ribbon cable gets two pieces of 2″ long tape wrapped around all wires. The lower ribbon in the pic- separate the last two wires from the ribbon, and wrap them with a piece of tape lengthwise.
Here are some links to ferrite tape manufacturers / distributors.
This EMI / noise mitigation was fueled by beer and rushed to press. Next time I do a mod I’ll have the video camera and whiteboard set up
IF you’re not a Taranis owner, check it out here- http://www.alofthobbies.com/frsky-taranis-x8r-combo.html
I overloaded a circuit and popped a breaker, nothing that I hadn’t done dozens of times, but this time it took out my imax lipo charger. Well, half took it out. The display went strobe-like and was unreadable and I wondered if it was the display itself, or the ARM processor. I had a smaller display I kept for my Arduino projects and gave it a shot before tossing the the charger in the trash. Success.. Now just to mod the case to hold the smalled LCD screen.
And for all the complainers, haters, nincompoops, pissypants….