Getting harder?

In all the years I have been involved in amateur radio (it started in 1961!) my main interest has been QRP (low power). 

In recent years the local noise level especially in urban areas has gone up, mainly because we have more gadgets and chargers. These often use switched mode power supplies which can produce a lot of noise. Taken together these can increase the noise floor. The result is weak signals can be buried in the noise.

Sadly, this means QRP operation can be harder. 

The problem is not so much the low power but the noise floor at the receiving end. If you have an electrically quiet QTH, you can still dig these signals out. Such sites are becoming rarer.

Probably there is a power below which it gets much harder.  At very low power it is easy to be clobbered by a stronger station as well. 

Thinking of the future, I suspect 5W QRP will be a good choice.

Ultra-simple transceiver

Many years ago I set out to see just how simple a viable transceiver could be made. It was published in GQRP SPRAT. It certainly works! Others built it and have worked some remarkable DX. It is also on my website.

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

QRP operation

Ever since I started in amateur radio I have enjoyed QRP.  DXCC was worked with 10W SSB on 10m with a low dipole in the 1980s.  

These days with FT8 basic QSOs are even easier. In my experience 5W FT8 or less and simple antennas are all that is needed to work the world. Of course 1000W and a big beam would make things easier, but where is the fun?

There is a whole array of QRP radios available either as kits or ready built. I guess the choice now is greater than ever.

Pititico 1 transistor transceiver

You may be interested in this (and other) videos on the Pititico transceiver on DX Explorer. 

As there is no amplification of the audio on RX I imagine it is not very sensitive so probably safer to call stations you can hear. Putting out a call you might squash another station already there that you cannot hear!

Does QRP SSB really work?

DXCC with 10W SSB was worked here on 10m back in the 1980s, so DX is rarely chased these days. Interesting to see this video comparing 5W to 45W on 40m SSB. There is a difference, but loads of contacts at 5W.

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.