Back to the radio

June 3, 2015 KK6GXG

To keep domestic peace I have not been building on the Beach 40 non-stop as I might otherwise do and there is a side benefit… By taking some time away from the build I can clear out the cobwebs and refocus on the greater project to check my thinking and my work.

I still need to do testing on a few of the sections. However I have all but two sections assembled with only minor followups. I need to figure out the value of the common emitter voltage limiting resistor on the Audio Amp and I need to wined and connect the two bifilar toroids in the RF Amp.

The last two sections to build are the Low Pass Filter and the T/R Switching sections. The bit that I have been burning cycles on is the T/R Switch. I want to do something that consumes the least power overall at-rest, something basic and bulletproof.

My current thinking on the T/R Switching is a pair of relays, one NO and one NC. RX on the NC and TX on the NO. This way everything is normally in the at-rest state and I only need to run one power lead from the TX momentary switch to both power leads on the relays. Since I don’t have the relays in stock I will need to go get a pair. Sounds like a trip to HSC. 🙂

Once I have the relays I will draw up a new schematic for this section and get it posted on the project page.

While not working on the Beach 40, I did do some radio stuff. I picked up some parts for stock from Jameco one day, a bag of varactor diodes, then two days later went back to pick up voltage regulators, a bag each of 5, 9, and 12 volts.

The XYL went with me to a local Radio Shack that is closing down. We picked up a bunch of zener diodes, a pair of bridge rectifiers, and some mechanical connections at 80% off. There wasn’t much left to pick through. I also found a pair of NO SPST relays which got me thinking more about the previously mentioned T/R switching circuit.

I also ordered a few bags of various op amp transistors that are frequently used in radio circuits. Purely a stock order, and I’m pleased to say the parts bins are slowly filling up and I am getting to the point I think I could actually build my next radio without going out and buying any parts. This is a good thing and I’m fairly certain my wife will agree.
Sneak Peak: I’m thinking about a Beach 20…

Also radio, not Beach 40, the beginnings of research on VFOs. I have been looking at a lot of material on VFOs without finding what I am looking for. I want something small physically, low power consumption, as close to all discrete components as possible, all readily available parts, stable, and a wide tuning range. A tall order I think.

20150603_105313 — First pencil sketch, next into the lab book and beyond

A first design only slightly out of specifications is this one I worked up from a test circuit diagram from N6QWs VVC page and the NE/SA602 spec sheet. It will be my VXO-X01 build. 😉

An Experiments page has been set up to keep a log of these kinds of long-term projects. I haven’t created the page for the VFO research yet but that will be up shortly after I update the Beach 40 build page.

One other non-radio, well mostly, is the slow planned migration to Linux. I have been wanting to this for a long time but the last time I tried it wasn’t so well planned. This time I am running both Linux (Ubuntu) and Windows (8.0) side-by-side rather than one virtual. It will be a long protracted process this time but it should result in a much better transition.

That’s it for now. Trying to keep the smoke inside the parts where it belongs until next time,

73,
~Jon KK6GXG

Amature Radio

40 Meter DSB Coming Soon

May 31, 2015 KK6GXG

Busy weekend for me.

Before moving on to Beach 40 progress, I got something else in the mail. A frequency counter module I ordered off eBay for ten bucks. I am thinking about using it in a future radio project as a digital frequency display. Not sure what project, but it beckoned to me and I figured it might work out well.

In a related sidebar, I have been doing some VFO research. I have been looking at several options and one that seems simple and efficient is using varactor diodes to replace the air dielectric capacitors in tuning circuits. I have some ten-turn potentiometers and found a good deal on Motorola 68ρF varactors so I bought a bag of 100.

I found N6QW’s website with some great information including a test circuit for testing the tuning abilities of various diodes and transistors. Definitely more to come on this venture after the DSB project is done.

Now, on with our regularly scheduled program…

In the last post I talked about skipping the Balanced Modulator/Product Detector and moving on to the Audio Amplifier.

I built the Audio Amp and got everything all tied in to the panel mount components.

I still haven’t tested the Audio Amp yet and I am saving that for after I get all of the sections built out.

About the time I finished up the Audio Amp the 200Ω potentiometer I was waiting on showed up. With the parts in hand, I moved on to the BM/PD.

The BM/PD build went well. with no real surprises. The diode ring ended up being laid out in an actual ring configuration with the RF transformer being mounted right in the middle.

The one thing I don’t like about this layout is the really long lead from one side of the diode ring all the way around to the other side of the board to the potentiometer. I don’t know if I can come up with a better layout in a future rendition but for now it should be fine.

One of the first things I started with today was building the interconnect cables out of RG174 coaxial cable and SMA connectors. I considered MMX connectors since they just push on rather than thread on but they are way expensive. I have seen a number of builders use coax interconnects for modularized construction and it makes separation for experimentation much easier.

One cable I made was actually an antenna, a test antenna at least. For testing transmission sections giving them something to radiate out of. By using a receiver near the transmitting device I should be able to copy the transmission. It’s the one on the right if you hadn’t guessed.

Cables, of any kind, are one of those things that can seem fairly easy to do, but when they go bad, they can go epicly bad and it can be hard to detect. The only preventative effort I know of is to take your time, use a light touch, don’t force things, and pay attention to detail.

I made 4 interconnects, 1 antenna, and one single end cable for connecting to the antenna outlet. It took a coupe of hours, but all of them are solid mechanically, and test to be solid electrically.

After getting the cables done, I hooked up the antenna and one of the interconnects but I still haven’t done any of testing beyond the Local Oscillator.

I have a lot of testing to do but I’m almost done with the modules so I wanted to plug away and finish up the modules.

The last thing I worked on before turning off the soldering iron was the three stage RF Amplifier.

The pic is the first stage, a buffer stage. I started the board with a configuration in mind but by the time I got to the third stage I had shifted a few things around.

One thing I wanted to point out is the spacing of the stages. In this pic I have most of the second stage done and the pads for the third stage laid down. The gaps between stages are for the addition, if needed, of shielding between the stages. This amp is fairly low power so I don’t think it will need the shielding, But I wanted to make the option available.

The third stage saw several pads moved and things reconfigured a little. The yellow leads are the RX Amp Bypass (short lead) and Amplified RF (long lead) lines going to the relay circuit which after a lot of thought this evening will be replaced with cable ports and the relay section will be moved off this board entirely onto it’s own module.

The other bit on the RF Amp board that still needs work are the two bifilar toroids that still need to be wound and installed. It sounds like a lot of work still to be done, but it is getting very close to First Contact.

Thats all for this post. May the magic smoke remain contained in all your circuits.

73,
~Jon KK6GXG

Amature Radio

RTFM aka Read The Datasheet

May 28, 2015 KK6GXG

A lot going on these days. Lets start with something educational… No, don’t run away… it’s not that bad.

RTFM or Read The Freaking Manual is directed in this case to datasheets for semiconductors. And this is where we begin our lesson for today.

20150527_113247 — The VXO dismounted from the LO/Buffer for testing

I have been working on the Beach 40 project for a few weeks now and have made some progress but I was having some difficulty with the VXO (variable crystal oscillator) and the LO/Buffer (local oscillator and buffer.) The oscillator section is supposed to generate an RF carrier frequency, in this case close to 7.2 MHz. I wasn’t generating the carrier and I couldn’t figure out why.

I decided to put these sections aside and move on to the next section and ruminate on the problem for a while. The next section in line was the Balanced Mixer / Product Detector but I was missing a component that I was still waiting to arrive, so on to the next stage, the Microphone Amplifier.

20150525_135559 — The Mic Amp has the mic element temporarily direct wired for testing

Laying out the parts physical locations on the circuit board I came to the transistor, one I hadn’t worked with before. So I decided to look up the data sheet and be sure of the pin-out. It wasn’t what I was expecting it to be, and then it hit me, like a Log from BLAMO! My oscillator wasn’t oscillating because I had the pinout wrong on the transistors! I finished the Mic Amp and the part arrived for the BM/PD.

20150527_154019 — The Balanced Mixer/ Product Detector. Ain’t she a beaut!

I moved on to the BM/PD and finished it then looked up the transistors on the LO/Buffer and sure enough, I had them in backwards.

With a little coaxing and cajoling, and construction of a really scaled down crystal oscillator for testing, I got them turned around and everything back in place, well sort of. I missed a jumper and had to go back and solder that back down, but the after that the oscillator was oscillating like a good little oscillator should. Oscillation!

With a little tweaking and and the removal of the Fine Tuning circuit that I still haven’t figured out, I am back on track and only three sections shy of a full transceiver. At present I have the sections built for a QRPpp transmitter a very, very, very, very low power transmitter, somewhere around the microwatt range but I should be able to modulate a voice transmission a foot or so to my DC receiver.

The Mic Amp test is actually a test of the VXO, LO/Buffer, Balanced Mixer, and Mic Amp sections and has me transmitting some AF (audio frequency) along with the carrier through the Balanced Mixer to help locate the signal in the band. Once I locate the signal on a separate receiver it’s time to tune out, or “suppress”, the carrier signal on the BM/PD section. I’ll be doing just that in the next few days. Hopefully I will remember to video the test and post the video.

I already checked out the VXO and LO/Buffer when I checked the frequency. I can check the Mic Amp just by hooking it up to a speaker, which I will. Then the BM/PD gets it’s big on-air check out.

20150527_163139 — CCW from top left: Balanced Mixer/Product Detector, Local Oscillator/Buffer with VXO mounted vertically, tuning capacitor, Mic Amp, and Audio Amp with just the tinned pads on the board

All that’s left to have a working receiver is building the Audio Amplifier which I have already laid out, I just need to solder the parts down and test. After that I need to build the RF Amp to have a transmitter. I will want to also complete the Low Pass Filter before transmitting though. I don’t want to splatter the band or anything.

So the schedule for now looks like a completed Beach 40 transceiver should be on the bench next weekend or there abouts.

That’s all for today.

73,
~Jon KK6GXG

Amature Radio

Radio Kits

May 23, 2015 KK6GXG

When I first started this blog I planned on posting a separate page for each project I did. After some thinking on the matter I decided that scratch-built projects would have a page dedicated to them.

20150518_213658 — L/C Meter IIB from Almost All Digital Electronics AADE.com

The last post was an example of a project while important and interesting, I don’t think it rated a page. I am of course referring to the post on the AADE L/C Meter IIB. Part of the reason I’m not devoting a page to the project is that it is a kit, a great kit, but still a kit.

Don’t get me wrong on this, kits can be a really useful tool. Often times kits can cost less that the parts purchased individually. They can also be useful in overcoming sourcing issues.

20150403_090944 — Scratch-built, from paper to product

For the beginning builder kits are a great way to get your feet wet and try the building process as well as exercising the construction skills needed in scratch-building. A kit can get you on-the-air faster than scratch-built as well. Kits give a potential scratch-builder a chance to see if they actually like building.

Kits also offer a choice for the builder. The kit can be built by just filling up the board following the instructions, or if you are looking at going scratch-built later on, taking the time to trace things out and compare the schematic with the board layout, and understanding what components perform what function along with how and why things are placed as they are goes a long way in improving your understanding of the circuit.

While kits can be a good learning tool or refresher for the builder, they off-load a lot of the mental gymnastics involved in design, sourcing, layout, placement, and proximity matters. Or at least they should, a poorly designed kit can be a real challenge for even the most skilled builders.

I decided to post about kits rather than page them because of this off-loading. While the kit may be of educational value, it is the mental exercise not the physical work that provides the real educational benefit. I don’t think I would be bringing much to the table beyond the instructions that come with the kit.

Breadboard Radio Kits — 4 kits from BreadboardRadio.com waiting to be assembled

So don’t be surprised when you see a project as a post rather than a page. I will start the trend in my next post when I show off the BreadboardRadio.com kits I built before beginning my 40 meter Direct Conversion receiver. I will likely set up a Kits page as an index to kit projects if it looks like I need one.

Stay tuned and 73,
~Jon KK6GXG

Amature Radio

The AADE L/C Meter IIB

May 21, 2015 KK6GXG

If you don’t work with RF electronics the need for an L/C meter may not be readily apparent. If you work with RF, you have likely found capacitors and inductors in the junk pile and played hobb trying to figure out the value, unless of course they were marked.

My first homebrew toroid inductor. Aint she purdy?

If you wind your own inductors or make your own capacitors the need for an L/C meter is a no-brainer. I bought a cheap Chinese manufactured meter and it was no bueno. No redeeming qualities what-so-ever.

Within the Amateure Radio world AADE (Almost All Digital Electronics) and the L/C Meter IIB has earned an almost legendary reputation for being just the piece of equipment the homebrew ameture needs.

Being a homebrew ameture and a recycler of electronic components, I decided to buy the L/C Meter IIB kit and build it. The kit itself is very straight forward. Assembly is well documented and easy to follow.

I have been generating a lot of solder smoke lately so I may have an advantage here in assembly speed but I went from shipping box to functioning test equipment in about 4 hours.

Starting with full parts inventory I went right into construction. The parts list is only one sheet and it is very detailed. After checking in all of the parts and tagging them to the parts sheet I fired up the soldering iron and started melting metal. Filling the printed circuit board didn’t take long at all.

The only hiccough was technician error. I got all of the components soldered in, mounted the board in the back of the case, mounted the LCD, and plugged in the battery. When I turned on the power switch I got nothing. I knew from reading the instructions ~~fancy that~~ that a common oversight is that the contrast pot should be turned fully clockwise. When I went to check the pot I noticed something missing, I forgot to install the IC’s in the sockets. Doh!

20150518_215451 — A great product that supports a US, family owned and operated business AADE L/C Meter IIB

After installing the IC’s I checked the pot and Voilà! A working L/C meter.

At $100 a kit that looks as simple as this one does you may be tempted to buy a cheaper factory assembled meter. I would strongly advise against it. A comparable factory manufactured meter will set you back at least twice what the L/C Meter IIB will, probably more.

I purchased a cheap meter for $38, paid $6 for shipping and another $8 to return it. Sure, it looks nice but it is complete garbage.

And if you need something else to push you over the fence on this purchasing decision, buying from AADE supports a family run US business that takes pride in the work they do. Now that’s a bargain at any price.

Solder smoke is filling the air as I continue work on the 40 meter Beach 40 DSB transceiver so check the build page for updates. I will be making an update tomorrow!

73 for now,
~Jon KK6GXG

Amature Radio

Work On The Beach 40 Begins

May 17, 2015 KK6GXG

Back to building! I finalized the drawings for my implementation of VK3YE’s Beach 40 DSB Transceiver. I created a project page for it here. I also finished the the “final” version of the diagram, at least until I get the physical build under way. I will be updating the diagram on the project page but not here so if you are interested in this project, check out the build page.

VK3YE-Beach-40-KK6GXG — Here is the full diagram I completed today. Click for full size image

While I am heating up the soldering iron tonight, another important part of this project is the documentation. Not only am I going to be updating the project page as the build progresses I will also be keeping a lab journal.

This is something new for me. I have never been skilled at keeping lab notes. This is something I need to work on now that I am getting more involved in RF electronics as an experimenter.

That’s it for now. More to come.

73,
~Jon KK6GXG

Amature Radio

Marker Generator and more

May 13, 2015 KK6GXG

Picking up where I left off in the last post, I got the drill bits and finished the 40 meter Helically Wound Vertical antenna. I will get a project page up soon.

Now when I say “finished”, what I mean is the antenna is useable. I still need to seal and cover it but I wanted to get it all tuned up first. As far a receiving goes, the vertical is out performing the dipole strung in the house just sitting on the floor leaning up against the wall next the operating station, so it’s looking good.

I need to finish the tuning with a transmitter on it. Since the only transmitter I have for 40 meters is a CW 250mW transmitter I am holding off on that.

In the mean time I put together a Marker Signal Generator. The design takes an 8 MHz crystal and divides the signal down several time ending up with the desired 1 kHz signal with many harmonics to mark out a tuning dial in 1 kHz increments.

It was fun to build and I leaned a little about some ICs I had never used and some of the basics of working with multiple devices in a single package.

When I came to function, I was very disappointed. The oscillator was anything but stable and we very dependant on an extremely stable input voltage. The onboard diode voltage regulations stunk so I tuned down the power supply from 12 volts to the 5 the ICs need.

At this point I was finally able to calm down the oscillator and get close to 1 kHz I was hoping for. A millivolt up or down and the frequency was out. Not a particularly useable device as it sits but it does give me some ideas for using out of band crystals to generate a signal.

As always, this is the whole point, to experiment and learn about RF design by doing, not just reading and modeling on a computer.

The big news, and the reason I missed a post last week is that I have been doing some research on finding my next big build project. The winning design was the Beach 40 by VK3YE. I have been scouring the web looking for a simple phone (voice) transmitter. I was hoping for SSB (Single SideBand) but the Beach 40 DSB (Double SideBand Suppressed Carrier) is simple and straightforward as is.

Being me, I had to make some modifications to the design and tweak a few things. One of the great things about this design s that it uses discrete components rather than ICs.

At one point Peter (VK3YE) recommends changing the audio amplifier to one that uses the LM386 chip rather than discrete components because the output is rather low. Since one of the main reasons I chose this project was to keep to available discrete components I went out in search of a different audio amp.

Enter Arv Evans K7HKL and his Discrete Component AF Amplifier paper. By the way, at least via email, Arv is a really nice guy. Thanks for the help Arv!

Now with the circuits mostly settled and parts enroute, Digi-Key arrived a day early! 🙂 I sat down tonight and began kitting the parts for each of the transceiver subsections beginning with the Super VXO. I am only installing one crystal set right now but the plan is to set it up for several banks of crystals. I also had some ideas as to using the banks for multiple bands as well as sections of a single band, but that’s for later.

I also kitted the Local Oscillator/Buffer and the Balanced Modulator/Product Detector sections. There are a few bits that will need some refinement, mostly inductors, but these will be addressed as needed.

And speaking of inductors, since I sent back that crappy one I am still in need of one. I will be ordering one tomorrow because I wont get far in this build without one. The goal is to have this radio up and running before Field Day June 27-28.

Look for a project page soon.

Till next time, 73,
~Jon KK6GXG

Amature Radio

LC Meter Disappointment

May 5, 2015 KK6GXG

The Newcason XC4070L Handheld LCR Meter I ordered showed up on Monday. Wow, what a disappointment. No stability in measurements whatsoever and I’m not talking bounce between two consecutive numbers. 32 ρF to 64 ρF on a 50 ρF capacitor which by the way I checked with another meter that pegged it at 49 ρF. This puppy is on the express return train.

I did get something good done while testing the meter. I wanted to make a set of alligator clips on banana plugs to easily check through-the-board components. I wanted to make a set of these for some time. Now I have them.

One of the advantages of using these is that it reduces the inductance and capacitance errors that can be introduced by some meter cables and close proximity of hands.

In other pending order news, I have the tap and dies for the antenna. Of course I am waiting on the drills. So there the tap and dies sit, on the group W bench, just waiting on the for the drills.

As soon as I get the drills I should be able to get all of the antenna parts all connected up so I can start tuning and testing. Then I can move on to the ATU.

Thats it for now, 73,
~Jon KK6GXG

Aspirations

Package Pending

May 2, 2015 KK6GXG

I have some tap and dies on order that I need to finish the 40 meter vertical antenna. I also have some parts in transit that I need to get started on the antenna tuner which is the next project on deck. As well as the project parts I ordered a couple of items for stock.

One acquisition I have been needing is an LC meter to test inductors and capacitors.The one I ordered measures inductance (L), capacitance (C), resistance (R), and it also checks transistors. A very handy piece of equipment. I have several meters, digital and analog, nearly all measure resistance and voltage, a couple can check transistors, and one can test capacitance in a very limited range.

Since I am planning on making my own air dielectric capacitors, and a variety of inductors and transformers, having a wide scale LC meter will make this work much easier. It will also be a lot of help at flea markets and garage sales to check out components that I am interested in.

With all of this in transit I have some time to get some administrative stuff done. The main thing is to plan out the next few projects. The basic 40 meter direct conversion receiver is done, the antenna is almost done, and the antenna tuner is next with most of the parts enroute, so it makes sense to build a transmitter for 40 meters, I am leaning towards a CW/SSB transmitter.

One of the reasons I want to build CW/SSB is that it will add several other digital modes as well. Many of the digies can be connected straight throught the audio in/out ports on a computer or a handheld device. Leaving only the need to provide a key or key signal to switch between the receiver and transmitter which could be done manualy or by serial connection to a RT swiching circuit in the radio.

It sounds a lot more complicated that it really is. With a little planning and some experimentation setting up a cable with a couple of connecters on each end will do the job nicely.

I will need to add a couple of circuits to the receiver at some point in the near future as well. An second stage audio amplifier is a must, and a switchable audio filters with bandwidths for CW, SSB, and something in the middle for digi, between first and second stage audio amplification. Neither of these should be all that dificult.

Once I get the 40 meter station all put together I will start work on building another station in another band. By this time I will have figured out a lot of the kinks and bugs and beable to build the second station much more efficiently.

At this point I’m not sure what the next band will be. There are 16 amateur bands currently with the potential of two more that I can gain access to under an experimental license so it is wide open. Each band presents new challenges, ether in technique or materials.

VHF and UHF present strictor tolerances and microwave (UHF-SHF) presents even more challenges. Most bands in HF will be about the same requirements as 40 meter since it is about the miiddle of the HF band. MF presents some challenges in radiators (antennas) because the wavelength is so long. LF presents more challenges in power and radiaors, not to mention the need for that experimental licence.

Fortunatly ist’s all about the fun and learning. As long as I am learning new things, honing skills, and having fun it’s all good.

Until next time, 73
~Jon KK6GXG

Politics, Ramblings

Head in the sand…

April 29, 2015 KK6GXG

The topic of current events arose in conversation this morning. The two major events that came up were the Nepal earthquake with the ongoing humanitarian aid efforts there and the situation in Baltimore.

In Nepal not only is there the topic of the humanitarian aid, but also the political elements involved with the relief communications problems. There is a long story about amateure radio and the Nepal governments apparent conflicts with the emergency preparations that some hams have been working on for years. It may have a connection to many lost lives which may have been saved had they not been blocked by government efforts. I am getting this information from a directly involved party, and I have every reason to believe him, but I know very little about the actual situation from first-hand knowledge. So while my heart goes out to the people of Nepal, it is hard to make educated comments on the political front.

With Baltimore, well, this is a tough subject to broach. As the title of this post says, my head has been in the sand. I know very little of what is actually going on. I did see the video of the mother who when she saw her son rioting and throwing rocks at police went down to the site, found him, and smacked him around. Nice to see a parent taking responsibility for their child by the way. I don’t know how much of or even if that story is true, I only saw one blog post and a video clip.

Where I’m going with this is I haven’t been paying a lot of attention to the media’s reports of what’s going on in the world lately. Mainly because these days the media, all media, has an agenda. They all want to have eyes on their “data.” Their revenue stream depends on viewership, so they must sell there “data” in whatever form to make money. Big Media has a market and a demographic they are selling to, so their perspective is skewed to that demographic. Further complicating things is the political connection of the management and owners of the media outlet further skewing the perspective and agenda.

Just to be perfectly clear, I don’t like or trust Big Media. I bet you already figured that out though. As the quote goes, “Follow the money.” Who has most of the money in the US, media and financial institutions. Who holds the most sway with elected officials, media and financial. Who shapes public opinion, media and financial. Do you think credit companies and banks want you to be debt free? Hell no! They would go broke. Do you think Big Media would be making billions if there was no public conflict? Same thing, hell no!

There are miscreants, there are bad cops, and the behavior of both is reprehensible, but these bad actors are in very small numbers. They are the instigators, knowingly or not, doing a job they are employed to do. Who do you think is at the root of backing and organizing the instigators?… This isn’t just about Baltimore. It is the direction the country is being manipulated. I know almost nothing about the situation in Baltimore. I have heard a lot, but I don’t KNOW very much at all. I refuse to be manipulated into an opinion by someone elses political/financial agenda.

I can only loosely observe trends. There are few verifiable facts being made available, and fewer sources that can be trusted to provide these facts with any modicum of objectivity. Observing trends and trying to sus out which way the wind is blowing is about the best we can hope for. Getting incensed about something because the media says its true only serves to distract us.

When a population is polarized, agitated, and distracted it doesn’t see the real problems it faces, the real instigators. Who is polarizing, agitating, and distracting us? Follow the money.

~FlyBoyJon

Amateur Radio, Emergency Communications, Traffic Handling and more