Tuesday, October 06, 2009

First HB-1A contacts

I made a couple of CW contacts with the HB-1A QRP rig today. It was harder going than I expected, as no-one replied to my CQs, and I couldn't use 20m because the noise level is so high I have to use the MFJ-1026 noise canceler, and that requires a radio that provides a TX switching signal, which the little QRP rigs don't do. So I had to hunt around for people who were not calling CQ DX and also sending at a speed that is comfortable for me.

On 30m I worked Vlada, OK1FLK who was running a 40 year old pair of ex-Army transmitter and receiver and 150W into a long wire. Then I went down to 40m and found Fred, DL3AMB near the European QRP frequency of 7.030MHz. Fred was using an Icom transceiver but only running 2W so this was a two-way QRP contact.

During lunch I set the HB-1A to 10.1387 USB and fed the output to my Samsung NC-10 netbook to see what WSPR beacons I could receive. I returned to find a whole screenful of decoded stations. The HB-1A is certainly sensitive and stable enough to use as an WSPR receiver but of course it has no audio modulator so it can't be used to transmit.

One problem I have found is that the audio starts to clip on any station whose strength exceeds S9 on the HB-1A meter. This distortion is evident using different headphones and earpieces, and even feeding the audio into a computer soundcard so I can look at it using a digimode program as an oscilloscope display. From the comments received so far on the HB-1A Yahoo! group this isn't a common problem so I guess I'm just unlucky. I don't have much in the way of test equipment so I can't troubleshoot the problem, but hopefully it's just a matter of adjustment and someone will tell me what to tweak.


2E0HTS Simon said...

I like the idea of a neat little rig for walking/camping trips and holidays. Your new HB-1A QRP rig looks well worth the cash and now you have had some good results I bet it would be very good out and about.

Enjoy your tinkering in test mode!

goody said...

I'm thinking you could make a circuit to look at the voltage on the paddle contacts and drive a transistor for a TX switching signal.

For the clipping problem, I'm wondering if a 10 dB attenuator in the front end would help. You could use a relay driven by the TX switching signal circuit to switch it out during transmit, or perhaps there's a way to do it with diodes.


Anonymous said...

Hi Julian,

If you press the ATT/IF button once, This [laces the RX in attenuation mode. Maybe this will stop the clipping of S9 signals. If so, this would be a simple fix when necessary. Just a thought ! Best of luck with the new rig.
Maurice G4DVM.