What’s this?

Whilst rummaging through drawers in my shack trying to find a power supply for an unused PC, I came across this TX. I have no recollection of making it, but it looks like an OXO QRP CW transmitter. It must date from the 1990s or early 2000s. 

Pititico ultra simple transceiver

As far as I can tell this ultra-simple transceiver has a passive receiver. It was designed initially by PY2OHH and this version appeared in this Canadian club magazine. Others have made versions for other bands. 

Clearly with such an insensitive receiver, it is better to call others calling CQ as you may not hear others on the frequency. The RX sensitivity will depend how good the headphones are.

See https://www.calameo.com/read/0076654746ade7e23a716 .

See also https://hackaday.com/2024/07/12/tiny-transceiver-gets-it-done-with-one-transistor/ .

Someone else trying my designs

 It is always good to see others trying their hand at my designs. DX Explorer has a video of him breadboarding my 2 transistor 80m transceiver. My designs are always a starting point. Pretty sure you will be able to improve them!

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/80m-xbm80-2 .

QRP radios

There’s a wide choice these days in QRP radios unlike years ago . I expect this is, in part, due to the popularity of SOTA and POTA activations where small size and weight are important. One example is the transceiver shown in the photo.

QRP portable

This photo was taken many years ago in my mother’s garden. Also, judging by what hair I have, which was still black, I would guess this in the 1980s. As I recall, I was using the 2m 200mW PEP MX2 with a 1W 10m homebrewed transverter all powered with a 12V 1A sealed lead acid battery pack. As I recall, I got all over the world with this set-up. The antenna was a base loaded whip on the grass.

One transistor transceiver

My attention was brought to this design yesterday. 

My immediate thoughts were than the TX would be fine, but the RX very deaf. For local QSOs and experiments fine, but it could not be seriously used as the RX would not be able to hear who is on the channel. If the other station TXed first, you would know the channel was clear.

See https://semara.org/tech-talk-a-one-transistor-marvel-transceiver/ .

CDARC talk on my website

I think this file is now shared. If you have problems getting it, please discuss with me. I created it in (free) Open Office and saved it in Powerpoint. 

Open Office is totally free and every bit as good as Microsoft equivalents in my view.

There is a link on this page below.

See https://sites.google.com/view/g3xbm4/home/other-amateur-radio/cdarc-talk-march-2023 .

Extreme QRP?

In my emails today was the Elecraft Newsletter. 

One of the articles was about "extreme QRP". This looks interesting I thought, only find out it was about 1W. To my mind extreme QRP is microwatts, not watts. I would have been more impressed if this person had got spots with 100uW rather than 1W!!

From my own tests years ago, well below 1W can get spots.

I know of at least one person who has been spotted across the planet with 20mW on 30m.

10m QRP transceiver

It is hard to think this is 10 years old! It seems like only yesterday. Maybe you can get some ideas from it. It was called the "Lesser Chirpy" as the original version chirped badly.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/10m-lesser-chirpy .

How simple can you make a transceiver?

Many years ago, I built the XBM80-2 80m CW transceiver. It never got cased, but shows how simple a transceiver can be! Somewhere recently I was told that it is a good idea to keep DC from hitting the crystal earpiece. If this is the case, it is probably worth adding a DC blocking capacitor between the audio transistor and earpiece. I have no idea if this is an old wive's tale or fact.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/80m-xbm80-2 .

Different challenges

Next year, assuming I am still around (!), I should have some new QRP challenges. I hope to be active on 23cm and on 4m. Both are quite different, but should be fun.

The joy of QRP

In our hobby we all have different interests, and that is only right: it would be a sad world if we were all the same. Some like ATV, others chasing DX, others just talking with old friends on 80m. I cannot say how you get fun. Neither would it be correct.

My own "thing" is QRP (low power). Now, I freely admit that at times more ERP helps. However, especially on bands like 10m in the better solar years, the world can be worked with low power and simple antennas. This is even more true with modern modes like FT8.

Perhaps my G3XBM website may give you some ideas. Whatever, the next few years could be the time to give QRP a go. You might be surprised.

Classic QRP transceivers

Nothing compares with working hundreds or thousands of miles on an ultra-simple QRP transceiver that you made yourself. 

The challenge is often trying to make the simplest rig that actually works. Often it is receiver that is the weakest link. With modern rigs, mW signals can often be dug out of the noise.

One classic is the Pixie and its predecessor the Micro80. Pixie kits can often be bought from China at stupid prices. These work and allow real QSOs, but they are let down by the RX. The challenge is to get a rig where the RX is up to the job. Often I do not call CQ in case a weak signal I cannot hear is already there. With QRP, calling others is often a better approach.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/8040m-pixie-and-micro80-transceivers .

Operating outside

This photo shows me operating from the car some years ago (2012?). From this location on the coast in Devon I have worked the USA with 10m QRP SSB and AM QRP on several occasions. 

10m WSPR QRP TX

At the moment I am on 10m WSPR TX with 500mW. So far just local spots from G4KPX (14km).

UPDATE 1143z:  Still just spots from G4KPX.

UPDATE 2145z:   QRT now. Just 2 Gs spotted me all day.

Best ever QSO?

My best ever QSO was probably in 2007 when I had a 1W CW QSO on 6m (50MHz) with a station in the USA by E layer propagation. It was a very good 6m opening. My antenna was just the V2000 vertical omni. The other station was well equipped, but we had a solid QSO and I have the QSL card to prove it.

ICOM IC-703

This is the radio that preceded the IC-705. I sold mine many years ago to a friend in Cambridge and regret it. If you are after a basic HF/6m 10W radio, then you would be hard pressed to do better. It is the same size as the IC-706 range, but hard to find these days. One advantage is the auto-ATU, which matched my long wire on all bands from 80m to 10m. It would probably have done 6m too!

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/commercial-rigs/icom-ic-703 .

What is the best QRP transceiver ever?

Many of us enjoy the challenge of getting the most from the least. Some define this as the fewest number of parts or the lowest cost.

What do you reckon is/was the best QRP radio design ever? Tell us all what you think and why, and leave some links if possible.

Most designs are compromises. Ideally, I am looking for a rig that really holds its own on TX and RX. As an example, the Pixie and Micro80 had dreadful receivers. I am wondering if anyone has come up with a rig with a decent receiver?

Facebook memory from 2012

This appeared as a Facebook memory for today. It was 9 years ago. 

10m QRP WSPR TX (Wednesday)

As the 10m antenna was free, I put my W5OLF stand-alone WSPR beacon on using 500mW. So far, just a local spot from G4KPX (14km).