Some of you may be following the adventures of Peter Parker (VK3YE) and his latest version of a Beach Mobile QRP rig. Peter has been quite prolific over the past years and his various designs have been published in several magazines. He also has a great series of YouTube videos on his web site. It was one of these video's where he walks us through the circuit of the rig he has called the Beach 40, that started me on my adventure into QRP. I captured that video and sifted through it pausing as he completed drawing each stage and print screened them to JPG files so I could draw a complete circuit diagram. I only made one mistake that that came back to haunt me when I tried to get the receiver section working. I contacted Peter and told him I was thinking of desiging a circuit board so I could use it as a club project for my local radio club. He sent me contact detail of a fellow in the USA who had also drawn the circuit from the video so we could compare our circuit diagrams and discuss the project. Peter also kept me to my promise by emailing me some time later when he had not seen any progress on the corcuit board idea.
I have eventually finished building and testing a Beach 40 built on a circuit board, this was about the middle of Sepetember 2013. First I had it working as a transmitter only for a couple of weeks, talking to Trevor (VK5ATQ) cross band on 2 Metre. Once I had sorted out a problem with the receiver I listened to a couple of nets, could even hear the guys in the USA. Trevor who is the President of the VK QRP club, is also working on a Beach 40 but he needs a bit more encouragment to "get on with it". Once I started to search the Internet for information on QRP rigs and the technology I joined the UK and Australian QRP clubs, a good source of information and even parts from their Club Shops. Each of the clubs have good little newsletters and all the issues of the G-QRP club newsletter Sprat, is available on a CD ROM.
Made my first DX contact (well to central Victoria - Lansborough) on the QRP rig putting out an estimated one Watt on the 10th of October 2013, about a year after I had first started on this project. VK3VBC gave me a 5 by 5 report and was able to copy all I said without much trouble once I worked out I was over modulating the little beast. It has more than enough Mic gain when using an Electret microphone insert fitted to an old CB microphone case. He was calling CQ DX and I decided to give it a go.
The antenna I am using is quite poor, 8.5 M of Aluminium tube (the remains of a Moonraker Marine antenna lengthend) mounted on a verandah post and driven through a bit of 75 Ohm Quad shield and from an old Kenwood AT-230 ATU. Just tuned for max noise. The output from the rig is not enough to use the SGC-237 tuner that usually sits on this antenna. I have arranged a relay on the verandah post to switch the antenna from the SGC AATU to the 75 Ohm coax so I can use it as a receive antenna with BoatAnchor receivers. I have also designed a five channel distribution Amplifier to use with this configuration so I can tune several BoatAnchors to different bands at the same time. I have not etched that board yet but if it is a success I will put details on this web site soon. My usual HF antenna, a G5RV is on the ground while I arrange higher poles to support the ends. The centre is ten metres in the air but the ends are only about 7 metres and the wire now gets in the way of my three band HF beam I have just put up and a number of trees in the yard.
I have used a 7.2 MHz ceramic resonator and varicap tuning with a 10 turn pot. I experimented with all sorts of diodes, including real vericaps, and the best were higher wattage Zeners and BIG rectifiers. The one in the prototype is a P600-G-400V available from Rockby Electronics in Melbourne for almost nothing for a lot of them. This have given me a tuning range of 7.036 to 7.148 MHz without any trimmers etc. I would like it to tune a bit higher in the 40 Metre band so I tried two of these diodes in series and the VXO now tunes from 7.060 to 7.200 MHz, perfect. My next PCB design has provision for a trimmer capacitor just in case I wish to pull this range down a bit lower in the band.
The second photo above shows the addition of a N3ZI Digital Dial kit. These can be purchased from Hendricks QRP Kits. I have three of the 2012 versions of this kit that used all through-hole compoments and an LCD display, the latest version uses SMT components and a LED display.
The third photo shows the latest modification to the prototype, a four pole relay fitted so the microphone pre-amp can be switched to provide more audio gain on receive. This os to prove the concept of adding more audio gain on the next version to be built.
I am almost ready to assemble another Beach 40 board with extra audio gain on receive. This will be my about my 12th version of this project but I have only built two versions of the boards I have designed so far. The second board may never be finished by me, it was just an exercise in making sure I had the component outlines correct for the parts I that are available. Several people have put thier hands up to finish this one and I will suggest they use a four pole PTT relay or four pole toggle switch and user the microphone preamplifier for extra audio gain on receiver. Worth a try.
As I am looking at using this project as a club project for the North East Radio Club I am plannig a three board version.
1. A VXO plus frequency counter board using a counter circuit from RadCom first published in 2006 and updated in 2008.
2. A Receiver only board with a Dual Gate Fet or a J-Fet RF Amplifier and using the Spectrum Communications 10mm coils as a band pass filter in the front end.
3. A Transmitter section only board.
The idea of this approach is to encourage F calls to get involved. They can build it as a receiver and perhaps this may encourage them to upgrade so they can then add the transmitter. The three boards are the same size and the VXO and Tx boards each have a two pole relay to do PTT. To make switching simpler each board has its own balanced modulator/demodulator.
Visit the GQRP Club web site and see what resources are available to members. They even have at last count, representitives in eleven countries that makes paying you subsciptions very easy.
DownUnder we have the VK QRP Club, also often referred to as the CW Operators' Club, and it has a news letter appropriatley called Lo-Key. At last count there are members from eleven other countries other than VK land.
The process I use to make the circuit boards at home is from Jim's VK5JST/VK5TR EndsOdds web site. This web site has many worth while projects and tips for Hams, once you have visited it once you will go back often. I produce the ground plain on the component side of the double sided PCB by covering the side I do not want etched with clear Contact Sheet, the stuff often used to cover school books. Make sure you press it down very firmly onto the copper clad making sure there is no air bubbles as the warm etchin solution may expand bubbles and let the etch in where you do not want it.
My PDF file of Jims method for making PCBs
PDF file - Introduction to the Squid Pole Antenna for use with QRP rigs in the field
Some Squid Pole Antenna interfaces from the members of NERC
Peters description of the Beach 40
The circuit of the original Beach 40
More home made and kit built items
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Written by and Copyright, Phil. Storr © Last updated 11th December 2014