Hello everybody, I'm Greg from Locarno, HB9FAE.
I'm involved with QRP since 1992, when with a single transistor TX I had a 20 minutes QSO with a German Station on 3.5MHz.
Of course I had to build something better, and I saw the GQ-40 on Sprat magazine.
The project was easy to understand and no exotic parts was needed.
I had the pleasure to meet Sheldon Hands at the HamRadio in Friedrichshafen, a very kind person, and I hope that he is doing fine.
But since a monoband was'nt for me, and since Sheldon did'nt make the GQ-Plus yet, after a little bit of test, a 4 bands Premix-VFO was ready, and a 80-40-30-20 meters TRX saw the light.
At that time, my "big rig" was an FT1000D, and the second (older) one was and is a 4-C Line.
Pratas DXpedition was on the air, it was 1997, and the rig was'nt ready yet, all the frontend and filtering was'nt there, the antenna connected directly to the HPF505 mixer. All the rigs on, waiting for a signal from Pratas on 80m, and by my very big surprise the first RX noticing Pratas was the GQ! Believe me or not, the FT1000D has been sold.
My only mistake has been to make only 4 bands: anyhow it is the most used rig in my shack. It has a very, and I mean very, low noise, like an FM squelched RX. It is a pleasure to operate, pushing out up to 7 watts. I added a digital readout, an electronic keyer, and since my 6MHz ladder IF-Filter is 1000Hz BW, also an Audio Filter about 250Hz @ -3dB.
You should know that QRP is'nt so popular down here in southern Switzerland: one evening at the club I took the QG-MU(ltiband) along, and when the others asked what it is, I said "we gonna have DX contacts with few watts", and by the first call on 20m a JA came back, quite a big deal for us.
No need to say that some faces turned to "?".
Now to the rig itself: I warmly recomend this small rig to everybody, there is no hard stage on it, it is very stable: the only hard point is the power supply. By my first try, the voltage dropped on keydown and the monitor tone was somewhat instable: since the monitor is nothing else that your own sended RF going through the RX section, you have the situation under control all time. But an improved voltage regulator (I can E-Mail a diagram) resolved the problem.
There is no RF-Preamplifier, the filtered signal goes direct to the mixer (I did not go over 14MHz!), a first level Doubly balanced diode mixer will do (the more the best), the IF with MC1350 and the Product detector with NE602, using the internal oscillator, a simple way to build a great RX, with LM380 as an audio stage, definitely "big enough" to fill a noisy room.
The local oscillator is free running, no PLL or else, and this is a good thing. You will find about this advantage by comparing the GQ with another rig with PLL or DDS. I usually make a very simple test: I supply an RF signal from a generator to the RX and set the level to about S9; then I go away with the generator frequency and notice the frequency until NO signal is noticeable anymore. Try it out, you will be disappointed on what your "big rig" makes!
The TX is supplied with RF thorugh the Bandpass filter, that works 2way like the mixer, from a dedicated xtal-osc connected to the key line. The pre-driver is a dual gate mosfet, whom 2nd gate is biased through a potentiometer (Power level) that allows to turn the power down to nothing. It is followed by a driver and a push pull with power mosfets. You can easily run brick-on-the-key without heatsinks. I experienced also some "no antenna" tests without damages. On my rig the power drops a bit on 20m, I do not know about 10m, maybe because I use IRF510 instead of VN66AFD, somewhat better on higher bands.
The PI-filter is all the time in, and in my case I switch the various bands by relais, same for the Passband filter.
Another pro is the keying timing, very fine also on full qsk.
Most of my traffic is QRP and with the GQ: last year I also builded the HF-Powermosfet amplifier appeared on QST: now I can run my GQ at the 60w level (Vdss 40V) and I really do not need any other TRX.
But if you start a construction like this one, plan it for all band you need, maybe with a RF-Preamplifier for higher bands, so that you won't regret it tomorrow, like I do!
Take care to have a wide enough RIT/XITcircuit, for DX Pile-ups you will need it.
I will be glad to share my GQ experience with anyone who would like to contact me.
73 de greg HB9FAE
P.S.: Sheldon if you read this, pse drop me a line, just to know how are you doing! |
