4m

This is a band that is gaining in popularity. It is very good when there is Es, but it is also good for inter-G working. I am sure that with reasonable power and FT8 the whole of the British Isles would be in range. The new Yaesu FTX-1F is supposed to include this in European versions.  I would expect 6W and a dipole to reach widely on FT8 especially.

A while back I designed and build a 4m transverter that is on my website. It is only low power but managed to work well. It was in  GQRP SPRAT some years ago.

4m transverter

Looking through some old photos I chanced on this one of my 4m transverter. 

There’s no way I could do this now with my poor fine motor skills.

See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .

Fine motor skills - basically now crap

 

This morning, I came across this memory on Facebook showing a 4m transverter I designed and made some years ago. It was published in SPRAT, the magazine of the GQRP club. 

There is absolutely no way I could do this now!  My fine motor skills are basically shot and soldering anything is unbelievably hard.

Not one to be beaten, I do experiments that I can still do that do not involve building as much as possible.

2200m activity

 Apart from an unsuccessful test last year with my CW beacon, I have not tried TX this LF band. As my only suitable antenna is my earth-electrode "antenna" in the ground, I am rather hampered with my poor health. It is this or nothing.

Some years ago, I made a video of my LF transverter.

At some point I must repeat my test with my 2200m CW beacon.

Fixing my 630m transverter

My very old transverter used a 28.060 MHz local oscillator. I obviously went to 3.2 MHz in my newer design to reduce start-up drift. 

My antenna current meter is still missing. It is somewhere in the shack, probably in a drawer somewhere.

My first step is to see if I can detect my 3.2 MHz oscillator on the newer transverter.

By some means, I want to be on 630m WSPR TX this evening!

4m Homebrew transverter

 

I came across this photo yesterday. 

See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .

630m transverter

This was designed some years ago, but has appeared in QST and the RSGB book "LF Today". 

I wanted a simple way of getting on this MF band and this was the result. Several have since been successfully built. 

It produces about 10W into 50 ohms, but the ERP will be considerably lower depending on the antenna used. In my case, my "antenna" was just an earth-electrode "antenna" in the ground with the electrodes about 12m apart with the wire back to the shack along the fence not very high. I tried the wire on the ground and it made little difference. My theory is this forms a loop in the ground. The actual loop diameter will get larger as frequency is reduced. Such an antenna has been used for far field amateur TX tests (successfully) at well below 10 kHz.

Most nights my measured 10mW ERP was spotted in Norway on WSPR. It used the FT817ND in split mode TXing on 80m but receiving directly on 630m.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/630m-472khz-transverter .

First steps

Looking back, I noticed this photo that shows my first setup on 600m. Later we got an allocation at 630m.

4m transverter

The photo shows my homebrew QRP 4m transverter. Late last year it was resurrected and copied some Es despite not having a 4m antenna. 

See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .

137kHz (2200m)

It is a very long time since I was on this LF band. 

On TX, I have used my earth-electrode "antenna" in the ground and a loop in the garden made with 0.2mm diameter multi-strand wire.  Thicker wire would have been better.

On TX I used a QRSS beacon or a transverter, both home designed. I have been copied overseas. My transverter is shown on my video channel and on my main website.

For RX only, the antenna can be very small e.g. an e-field probe, also described on my main website.

23cm transverter has arrived

This came today from Bulgaria complete with a small test 2el antenna. Once I work out what leads I need, I shall try some tests with some locals.

There was, thankfully, no duty to pay.

As you can see in the photo, it is very small for 2W PEP.

23cm transverter

According to my tracker, this arrived in the UK on October 24th. It has still to be delivered. It is now November 3rd.

4m transverter

Some years ago I needed a way of getting on 4m. This transverter was the result. I have no idea where it is now! Possibly it is in a shack drawer or in the loft. I really ought to try and find it and give it another go, perhaps with a wire dipole. Several have been made since it appeared in GQRP SPRAT. It is also in my G3XBM Project Scrapbook and on my website.

See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter

According to the webpage I listened for a local station's personal QRP 4m beacon. I cannot recall using the transverter. Maybe it was with something else.

UPDATE 1345z: I have found the transverter! It was in the shack at the back of a drawer.  Assuming it still works, I must try it out. First I have to erect an antenna for 4m.

UPDATE 1409z:  In preparation for trying the band again, I started looking for information. At one time, the place to go was the 4m website, but I get the impression this is no longer well maintained. Instead I turned to the RSGB's 4m page.

UPDATE 1428z:   I have connected the transverter to the FT817ND and the 10m antenna. At the moment I am on 70.100 MHz USB dial FT8 RX. I hope the crystal is still on frequency. I must check this. Noise goes up when the antenna is connected - a hopeful sign. Nothing copied.

UPDATE 1504z: I am puzzled what is the best frequency to try for 4m FT8 RX. Some say 70.100 MHz whereas some say 70.154 MHz. Which has the best chance of spotting anyone please? The 42 MHz crystal is oscillating and on 42.000 MHz . Currently I am monitoring 70.154 MHz USB dial.

4m and Es

Within a few weeks (certainly in May) we will be back in the sporadic-E (Es) season in the northern hemisphere. 4m is now allocated in several European countries and my transverter is certainly capable of working across Europe on SSB. It is certainly capable of improvement, so do not be afraid to experiment.

See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .

4m - 11 years ago!!

This QRP 4m transverter appeared as a Facebook memory today. It was designed and made in 2011. It is hard to think it was that long ago.

See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .

137kHz transverter

 

This photo, taken about 10 years ago, shows my 137kHz TX transverter. I still have it...... somewhere.

See  https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/2200m-137khz-transverter .

472kHz transverter fault

Years ago, finding a fault would have been easy. Now, even in small steps, it is exhausting and hard. 

I think the issue is that the oscillator has stopped for some reason: I can detect nothing at 3.2MHz on a nearby RX.  I shall look again at the weekend as now I am so so tired! Just a few minutes is so taxing now. 

This may be as simple as a dry joint. I guess the first thing to try is retouching all the solder joints in the oscillator. It is most likely to be this. I had a diode probe, but I have not seen it for years! I guess I should check the DC volts around the oscillator before doing this.

In the end, the aim is to TX again on 630m QRP. Before the fault arose my measured ERP was just under 10mW. This regularly was spotted on WSPR in Norway.

Canadian 472kHz transverter

Allen VY1KX has kindly sent me a photo of the 472kHz transverter he has built. I built my original on copper clad board to ensure a good ground plane. I recommend this as it makes grounding easy. Allen's transverter is in the photo. 

See https://sites.google.com/site/g3xbmqrp3/mflf/472khz_tvtr

4m transverter

One of my Facebook memories today was this photo of my QRP 4m transverter designed and made in 2011. I have not been on 4m for a very long time.

The band is being covered on far more commercial transceivers now and there are far more countries on the band. It is ideal for summer Es.

See https://sites.google.com/site/g3xbmqrp3/vuhf/4m_tvtr

No 472kHz TX this season

For the first time in many years, I have not been on 472kHz WSPR TX this year. 

Although the real reason is laziness, I blame it on not replacing the wire used on my earth-electrode "antenna" in the ground. 

Although my transverter puts out about 12W into 50 ohms, my measured ERP is about 5-10mW only. Despite this, I was copied up in Norway most nights last season on WSPR.

Others who have built the transverter have had transatlantic WSPR spots on 472kHz (630m). This is one of the most simple ways of getting on 472kHz TX. My "antenna" might not be the greatest, but it does work and the neighbours, and XYL,  don't even know it is there! 

I have also used the earth-electrode "antenna" on 160m, 80m and 60m with success. It should also work on 2200m TX although I have not tried this.