A C-Pole Antenna for QRPxpeditions

I've finished yet one more version of my Crappie Pole antenna, this one based on KF2YN's ground independent vertical antenna (or C-Pole). See here and April 2004 QST, page 37, for more information. After trimming it a little it measures 1:1 at 14.060 MHz rising to 2.5:1 at 14.35MHz and 1.2:1 at 14.0MHz.

I found the choke balun to be key to making this antenna work. With no choke the SWR was over 14:1 at 14.060MHz and with a 10 ferrite bead choke the SWR was still 2.8:1 at 14.060MHz. What I'm using now is 15 turns of RG8X single layer wound on a 4" plastic coffee can.

This antenna is about 18' tall, self supporting without guys and has only a 4' x 5' footprint. It breaks down to a bundle 5' long. Physically it looks like a tall skinny goal post. Add a birdie and two racquets and it should fit well into a typical camping weekend.

View a video of me setting up this antenna at http://www.youtube.com/watch?v=nYn-GnwcSoE

Today I made several nice contacts using my K1 at 5 watts and this antenna including W8CQU in Ohio (599), WA3SLN in Pennsylvania (449), W0WCA in Colorado (449), KI0II in Colorado (549) and N4ESS in Florida (579).

This antenna is going with us when we go camping this summer. Thank you KF2YN.

Update: On June 23 I worked EA6UN on the Balearic Islands off the coast of Spain in the western Mediterranean Sea. That's over 4600 miles on my five watts and this antenna. I found Jurek calling CQ on 14.050 MHz with no responses. He came right back to me and gave a 579 report.

read more "A C-Pole Antenna for QRPxpeditions"

ESSB: Transmitted Audio Quality on Single Side Band.

Transmitted Audio Quality: If you are a serious SSB operator like I am then you will pay close attention to the transmitted audo quality of your signal. Two black boxes that you basically use for HiFi SSB are the 8 Band EQ and the EQplus produced by Julius Jones, W2IHY. I have found that these two gadgets produce a transmitted audio that is as close as broadcast audio quality as I can get on SSB and Julius did a great job. I get consistently excellent reports on my transmitted audio quality and have also found that with signals that I receive and find with exceptional audio quality that the station on the other side is running the same pair of black boxes.

The equipment used for transmitted audio at my station. [ Visit http://www.nu9n.com/intro.html on details about eSSB]

Following is a photo montage of some of the audio processing equipment and microphone that I use for ESSB:

read more "ESSB: Transmitted Audio Quality on Single Side Band."

Yaesu FT-920 HF Transceiver.

HF + 50 MHz ALL MODE TRANSCEIVER

Yaesu's engineers had dedicated themselves to the enhancement of Signal-To-Noise ratio in designing the FT-920. Since recovered audio is the most important consideration at both ends of the communication circuit, the FT-920 is particularly optimized for noise reduction, wide dynamic range consistent with excellent sensitivity, audio tailored to the operators own voice pattern, and ease of operation. The result is an efficient transceiver design without a peer in its price class.

High-Tech Receiver Front End
The FT-920's receiver front end, adapted from the FT-1000D and FT-1000MP legacies, utilizes an up-conversion technique, with a 68.9 MHz first IF being produced by the four-FET doubly-balanced first mixer. Following the first mixer, a four-pole "roofing" filter protects the following stages.

This front-end architecture results in excellent image- and intermodulation-rejection characteristics for the receiver system.

New-Design MOS FET Power Amplifier
Utilizing rugged MRF255 FETs in the final amplifier, the FT-920 produces 100 Watts of clean output power from 1.8 MHz through 54 MHz! Built into an aluminum die-cast unibody chassis, the FT-920's thermal dissipation capability is unnmatched in its class.

High Speed DSP
The audio Digital Signal Processing (DSP) system of the FT-920 runs at a blazing 333 MIPS (Million Instructions Per Second), providing highly-effective filtering and noise reduction with a minimum amount of distortion or "artifacts" that can degrade reception. Noise reduction, bandpass filtering, and auto-notch filters are provided, in addition to a microphone equalizer to boost talk power and enhance audio quality.

Oustanding Digital Mode Features
Easy interfacing to digital modes is yours with the fT-920, and its flexibility for digital operation is beyond compare.Both AFSK and FSK connetinos may be accomplished, and the AFSK line is isolated from the microphone jhack, so you never have to worry about a "live mike" while you're on PSK31. PTT, fixed-level audio output, and squelch status lines are also available.

And for connection to a tape recorder, a convenient "AF OUT" RCA-type connector simplifies audio interconnection, independently from the TNC connections used for digital transceive operation.

CW Operating Flexibility
For CW experts, the FT-920 includes a CW Spot control, for precise alignment of your frequency to that of the station you're working. You also get a CW Tuning Meter, CW-Reverse sideband selection, a CW Pitch control, and a CW Message Memory electronic keyer, with storage and recall access from the front panel.

Advanced Multi-Function Display
The FT-920's Omni-Glow™ display includes a specially-engineered wide-angle lens, to ensure clarity of viewing over a very wide range of angles. The high speed digital metering includes a "peak-hold" feature, to allow easy monitoring of peak signal, power, or SWR values. You also get monitoring of the input DC voltage, speech processor compression level, DSP relative bandwidth, Clarifier offset, and a host of other information including tuning meters for both CW and FM modes.

PA3BFM reviews the Yaesu FT-920

Processed SSB Audio

Those who know me and my transmitted SSB signals know that I care allot about the transmit quality of my signal. I am not one of those local DX'ers who run tons of QRO power and don't care about the quality of their transmitted audio (you know the ones with excessive power, terrible audio, over compression and splattering!).

The constant compliments I receive over the air on the quality of my transmitted audio are a testimony to the efforts put into the front end audio processing.

With the 3 main rigs that I run on HF, FT-2000, TS-870S and the FT-920, I have paid special attention to ensure that the SSB signal is transmitted either in enhanced or extended SSB. But thanks must also be given to many friends on air and off air who are professional broadcasters as well as professional audio engineers who have given me lots of advice in order for me to achieve my ESSB goals.

For the FT-920 it is run in enhanced SSB mode and I use a combination of the KAM RT-1 - Ribbon Tone Dynamic Microphone into a Behringer FEX800 Enhancement/Effects Processor + FEQ800 Equalizer and a Behringer "Shark" DSP-110 Gate/Compressor/Preamplifier:

Here are some videos of what HiFi or ESSB can sound like:

read more "Yaesu FT-920 HF Transceiver."

Yaesu FL-2100B HF Linear Amplifier

This is the station Linear Amplifier, it is a Yaesu FL-2100B which operates in Class B grounded grid configuration using a pair of 572B tubes. Max. input power is 1,200 watts PEP.

Additional box fan used for ventilation of heat placed on top of the FL-2100B:

SPECIFICATIONS
Configuration	Class AB2, grounded grid
Frequency coverage	160m - 10m including WARC bands
Plate input power	1200W PEP SSB, 1000W CW, 400W AM/FM/FSK
Plate voltage	2400V (no load)
Drive requirements	100W PEP for full output
Input impedance	50 ohms unbalanced
Output impedance	50 - 75 ohms unbalanced
3rd order distortion products	31dB or better at 1kW PEP
Tube complement	2 x 572B/T160
Cooling system	Forced air
Power requirements	AC 100/110/117/200/220/234V 50/60Hz
Current consumption (100-117V)	18A
Current consumption (200-234V)	9A
Dimensions	157H x 345W x 326D
Weight	Approx 20kg

read more "Yaesu FL-2100B HF Linear Amplifier"

K1 build.

40m Pre-Mix Oscillator Signal Spectrum and Plot
Pin 4 J6 Filter board



20m Pre-Mix Oscillator Signal Spectrum and Plot
Pin 4 J6 Filter board

Adjust the pre-mix filter using an oscilloscope and pin 6 on J6 filter board.
(nice thing is same pin both bands) You realy need 4 hands to video this so apologies poor video.


A signal at last!

read more "K1 build."

An SW-4 Mystery

A friend of mine noticed that my National SW-4 shown at http://www.prismnet.com/~nielw/nat_list/sw4.htm uses what looks like standard SW3 type audios as opposed to the National "Duo Coupler" mentioned in the SW-4 ad. Other National radios show a production process that used parts that were available. Close inspection and comparisons between National receivers of the same model can show undocumented differences in details. Are this audios replacement parts or do they reflect a production change to take advantage of existing stock?

As I looked at these audios I saw something else. Close inspection of my SW-4 bakelite chassis showed three large plugged holes and several plugged small bolt holes. Parts mounting and the quality of the work makes it appear that all of this chassis rework was done before most of the parts were mounted. Why all of the extra plugged holes? Was the chassis originally drilled for another product and then reworked? Was the chassis made from a piece of bakelite that already had a few holes in it? Did a worker make several errors that had to be fixed before the chassis could be used?

There are a few SW-4s still around. I wonder, do they show similar changes and reworks? Were these sorts of production techniques common or is this really a set that was carefully reworked at some point after it left the factory?

read more "An SW-4 Mystery"

K1 build RF part II

90% of TX side done now, just got the PA transistors and the transformers to solder in (just in place mechanically for now) and then that should be it as far as melting solder is concerned. There was one missing 473 (0.047uF) cap (C50) I have substituted in something from my own supplies that should work until Elecraft send a replacement.

The alignment for RX doesn't always seem to work for TX and the manual and notes say that the K1 uses the same filters for RX and TX and the uPC in it does a calculation and the ALC sets output power to less than 0.1watts

Anyway should be done soon. I am off to the Dunstable Downs rally tomorrow. Hope to be able to finish the build over the bank holiday.

read more "K1 build RF part II"

K1 build. Up to RF board Part I

Just finished the build of the K1 up to the end of the RF Board Part 1.

Short video of the finished article.


The current draw with the back light is 64mA.

RX side all done and aligned. I used three signal sources, an FT817, a USB Si570 and a Colpitts Crystal oscillator using 2N3904 and 7.040MHz and 14.060 MHz so should be pretty true but the frequency can be amended through the menus. But once amended for 40m automatically the signal frequency for 20m was correct.

I have done the alignment with a side tone at 600Hz feeding the signals into a PC and used adjusted with an audio scope, built with stereo audio and the side tone is working fine and both hand and paddle key work fine. I have left keyer at 16wpm for now.

I might have to adjust the menu for S meter readings that suit later as I have left the level at L50 which is the default. I was listening to a cw contest and some of the local stations were definitely S9 and appeared so but the weaker ones did not seem to move the S meter. AGC is audio derived so an s9+40 signal causes a 'blip' and the AGC attacks hard the AGC decays pretty slowly. Turn it off and no S meter.

About to get the TX side started.

read more "K1 build. Up to RF board Part I"

A 20 Meter Crappie Pole Vertical

This past weekend we had nice weather here in southern Minnesota....mostly sunny and temperatures around 70. I spent some time working on a new portable antenna and then using it on the air.

I was looking for something simpler than my 20 Meter Crappie Pole Vee dipole. I decided to try a quarter wavelength vertical. The March 2010 issue of QST has a good article on ground systems for vertical HF antennas. Based on that I concluded that a 1/4 wave length vertical with only 4 elevated resonant radials should perform fairly well. What I ended up with is a 16 1/2' crappie pole on top of a 4' base section. The crappie pole itself is non-conductive fiberglass. It serves only as a support for the vertical wire. The guys at the top of the base section are 14 gauge stranded copper wire. These are trimmed to resonate on 14.05 MHz and serve as antenna radials sloping from 4' at the base of the vertical to about 1' were they are each tied off with adjustable lines.

On Saturday while using this antenna and my K1 I worked WA0FJT in Independence, MO on 14.050. There was some QSB but our 5 watt CW signals were usually 589 both ways. I got on the air again on Sunday afternoon and worked WB4YXD (New Mexico), N4HUS (Arizona), W2LG (Florida) and KB2DHG (New York). All came back to my CQs on a fairly quiet/vacant band. Via email I even received a reception report from W1CTT (Maine).

The antenna seems to be fairly effective but the elevated 16' radials could be a problem, especially in a full campground or picnic area. I'll look some more for a 20 meter self supporting antenna that fits better into an average campsite

read more "A 20 Meter Crappie Pole Vertical"

SDR list

For those wanting to see a pretty comprehensive list of SDR options as they stand today then this link is seriously worth following:
http://f4dan.free.fr/sdr_eng.html

read more "SDR list"

ARCI 72 part challange - realised error

Morning after... over the shreddies and visual check I realised as I had swapped FET from BS170 to 2N7000 having run out of one TO92 version (see http://www.jaycar.com.au/images_uploaded/2N7000.PDF for the two TO92 pin configurations) obvious error... I had connected one of the FET switches for mute backwards at the LPF input (shared with RX as forms half the BPF), anyway on TX instead of the FET passing RF to the LPF instead I was feeding the RF directly into the RX chain (abt 4W). Oops! I hit the key for a second and seeing no RF out and a brief squeak/squeal from AF stopped and heard no RX afterwards. Damage done but no magic smoke!. The IRF510 PA still seems to work so I have a TX :-) anyway might explain why it doesn't work ho hum! The 8 pin DIL PIC 16F629 (like old 509) was hosed as a result as the switch before the AF stage sent the RF into the PIC pin instead!

Normally a sensible builder would have reverse diodes etc in line and plenty of decoupling caps, voltage regulator, used npn transistor to switch the FET's and added an extra stage on the LPF as only 30dB down but omitted all this stuff to manage the part count! I realised I could have saved 3 as didn't need the xtal filter input transformer and couple caps used to decouple DC I had doubled up in two places (BFO and VFO into mixers).

Had this been a DC RX then 72 parts easy.... still learnt I could build a half decent <600Hz IF filter with two crystals not 4 or 5 :-)

Going to be interesting to see how the others actually managed it.

read more "ARCI 72 part challange - realised error"

ARCI QRP 72 part challange - Going to miss it.

I am trying to get the project rebuilt/boxed after reworking the PTO. Unfortunately tonight after 3 hours trying I cannot get the cw RX/TX mute to function as it did and the TX has some nasty spurs so I've bust it somehow, and as not boxed up yet got to face reality I am not going to make the deadline to get this to FDIM so will not be entering. It is my own fault I mixed the Dayton and Friedrichshafen dates up so lost 5 weeks. Frustrated, angry and embarrassed all in one...

My one IC wasn't anywhere in the RF part I used PIC keyer that also controlled the RX mute (FET on the AF).

Anyway, when the w/e is over I'll write it up.

My final part counts were:

TX
13
Basically a VXO FET oscillator using an IRF510 followed buy a 3 pole LPF. Some pulling possible using a small trimmer cap. Built for 80m.

RX
57
BPF, that shared the TX LPF, FET mute of the front end and the AF section. DBM mixer, M5 Brass bolt PTO, 2 8MHz crystal c580Hz filter, 8MHz BFO (J310), RF amp/product detector (J310), AF amp (3 NPN).

PIC
2
PIC + one resistor. I would have added a side tone too but needed one more component!

72 total.

The whole lot could do with a bit more decoupling and as planned on battery use no main voltage regulation except one zener in PTO. I build every module on a separate PCB, manhatten/ugly style.

read more "ARCI QRP 72 part challange - Going to miss it."

What SDR kits are out there?

I was asked this at a rally demo recently:

>> I was talking to you at the Loch Erne (Enniskillen)Rally on the 11th April past.
I would like to know:
What SDR kits are out there to build
What would you recommend to start with and which one to work up too.
Where can I get them from and how much are they ?

> Any thing else that you think that I may need to know about kits and what software to use would be great.

The answer is going to take a while to formulate with all the information but this post will be a place holder for it.

I will fill out the sections below.

The initial starting places to look for information on building SDR kits could be:

http://www.wb5rvz.com/sdr/ Robby has written extensive notes on the construction of all sorts of SDR kits.

http://www.kb9yig.com is Tony Parks website he is 'Mr Softrock SDR' as the kits are his. You can order directly from him but there can be some delays as he does the kitting personally.

There is an Elecktor SDR project, don't know much about it.

The Genesis SDR project is a bit more advanced that a softrock and for those who do not like surface mount the projects are good. http://www.genesisradio.com.au/

I have a kit in the design phase.

There are plenty of others out there I just either don't know them or haven't mentioned them,

All these so far use the concept of a PC sound card and software to decode the signals and the bandwidth is between 48khZ and 192kHz which is fine for most uses.

Expect to pay anything from £20 - £200 for an SDR kit. Any SDR TX options should NOT be considered by a beginner unless you have the RX side working first.

No matter what the RF hardware you need to run software for SDR. Don't expect to run it on that old 386DX DOS based system you use for VHF logging It will not work. You will need a good sound card and any reasonably modern PC should do well. The larger the monitor and the higher resolotion the easier you will find 'looking' for the signals. I use in shack an old Pentium 3GHz laptop or a Dual Core AMD 2.8GHZ laptop, 24bit 96kHz external USB sound card and twin 17" monitors. All together would cost less than an FT940 would. I do demos at rallies with an ASUS eeePC 4G which cost me £125 from Toy'r'us and the sound card in it is brilliant 24 bit and 96khz no problem and a 17" monitor.

Another option that Pat Hawker G3VA talked about maybe 10 or more years ago is to use direct digital conversion and digital up conversion to sample and convert RF directly to data and visa versa... the constructions are not really for anyone but the seriously experienced and surface mount components rule the day, go to http://openhpsdr.org/ and you will find some more details. They use FPGA chips to do most of the digital signal processing. Some of the newest FGPA chips have huge capabilities but cost £10K (HPSDR doesn't use the expensive end ones!) and those are what the military and broadcast radio and TV use.

Non kit options:

RFSpace: SDR-IQ, SDR IP, SDR-14

Flex Radio don't know much about them... very expensive!

Software:

Lots of options but a major one anyone has to make is are you going to try to run SDR with Linux or Windows.

Loads say they want Linux as it is open source and all that but and I make zero excuses for saying this but 99.99% of them never code a damned thing and much of what they say is hot air. The choice is really down to what you run your shack with, most use Windows and some of the more user friendly beginner software is Windows based. Not to say the Linux stuff isn't but it tends to be written for specific functionality not overall usablility.

No excuses for recommending it, as I am supporting Simon Brown HB9DRV (He wrote Ham Radio Deluxe) SDR-RADIO (http://www.sdr-radio.com) which he has now released v1.0 of. It doesn't have TX support and a few other things just yet but it will and if you know HDR and DM780 it will integrate with those nicely.

Other options are: (Again all Windows and no source code available)

ROCKY http://www.dxatlas.com/Rocky/

M0KGK http://www.m0kgk.co.uk/sdr/index.php

WinRAD http://www.winrad.org/

A homebrew siggen I would advise anyone to try to look at building to look at image rejection is this

... I'll add to this as time goes on....

read more "What SDR kits are out there?"

ARCI QRP 72 part challange - Update

Further to my tests ages ago with PTO... http://rf.circuitlab.org/2012/01/pto-vfo.html

Here I am again with the same test rig but with a different construction technique. Again I post the information here incase others are interested in trying out a PTO.

I have fused a number of M5 nylon nuts together, super glued them and wound red electrical tape about them. Into this I can turn a M5 brass bolt. It is much more stable than the previous constructions. Anyway onto this I close wound about 45 turns (I didn't count them at this stage) of 28SWG enamelled wire.

Final construction of the coil and screw will involve moving this to the PCB and not being panel mounted. A second nylon bolt will hold the far end of the assembly 'true' with the brass bolt.

Then using the same setup as before I retested.

I can now get the PTO to operate between 4.673MHz and 4.3MHz which is perfect for an 8MHZ IF and 80m rig.



Anyway as this is a buffered PTO, needed a little lift in LO signal for the DBM but it added a couple more components to the count so will see how my rig turns out.

I'm not going to use any component that is not generally available and every one must be possible to obtain from the 'usual' suppliers.

Hope mine is going over to Dayton with a UK attendee.
My TX uses just 13 components, crystal controlled and there is about 4-5khz ability to shift frequency using two extra components. That was the easy bit.
My RX... I am still tweaking it a bit so the count is not up to date but overall I am inside 72.
The rig should have a keyer (so an AVR or PIC is my one IC!) but if I don't get the code finished, it won't.

Some images of various bits follow, it is my intention to build this manhatten/ugly style so no fancy PCB required.

The minimal component count crystal filter. "So how did I select the components to use"... no fancy calculus... I looked in the junk box and then through what 1% caps do I have > 300pf and found three 560pF, three 390pf and three 680pf. So I plugged for the 560pf and built this crystal filter.

Then just to check how it performed I used my trusty MiniVNA in transmission mode and took a look.

Nice sharp filter. Note I added the FT37-43 transformers after I measured it at c24ohms so used trial and error and made 12T:8T transformers so the input and output are both 50 ohms.
In this image the transmission appears to be down 20db (it isn't!)

The TX side is dead simple to keep the part count right down. I went for an IRF510 which adds some legs rather than a 2N3866 et al but this means /P use may be a little reduced.

The variable capacitor, series inductor and crystal are missing from this image but everything else is on the board. RF out is the white lead to left, key (basically short to ground) is the purple lead on right. The LPF is very simple just one half of a normal LPF to keep the part count down and I played about with values to get this to a reasonable level but seems to work, it is a single T50-2 and two 1000pf polystyrene caps as the oscillator is crystal controlled I did not see any spurs. I might grab an image of the spectrum plot and the LPF transmission graph and post them too.

Oh BTW don't copy the TX layout the above will not work, was an early version I took a photo of.

I went for a simple double balanced mixer. The two 0.1uF caps and 56 ohm resistor on bottom left is the AF output and they act as a RC filter. BFO in is top right, RF top left.

*** more to follow....

read more "ARCI QRP 72 part challange - Update"

More TZ-20 Amplifier

Work continues....

read more "More TZ-20 Amplifier"

SDR/QRP talk at Cambridge and District ARC

Just been asked to give a SDR/QRP talk at Cambridge and District ARC.
As I am working in Cambridge again I expect to be local again for a while so this looks possible. No idea about dates yet.

I suspect a talk/demo might be best.

I'll have some of the Softrocks built with me and a handful of other qrp kits and builds.

read more "SDR/QRP talk at Cambridge and District ARC"

K1 Build

Some photos here
http://m1kta.ham-radio-op.net/m1kta/builds/K1/

read more "K1 Build"