Last Thursday evening was the 4m (70 MHz) activity contest for March. I missed it!
My antenna is just my 2m big-wheel and coax matched via the auto-ATU in the FT-710. I have no idea how it performs with regard to gain, polarisation, or directivity. This I was hoping to find out! Maybe in April? My next chance looks like April 20th.
Later this spring, I should be able to operate properly on 4m. Up to now, I have only used my homemade transverter.
I intend to erect a 4m halo. Hopefully, I shall be able to work some Es on 4m later. I have not seriously tried 4m TX for many years.
It would also be worth me trying a few 4m activity contests.
PJ4MM has also got a permit to TX on 4m. When the Es season comes, this will be an interesting path from Europe.
As far as I know, this is the first amateur in the northern hemsiphere in Region 2 to get a transmitting permit.
I think VP8 in the southern hemisphere has 4m, so this could be an interesting TEP path.
This evening is the 4m UKAC activity contest. Although I have no 4m antenna, I may take a peek on RX. The contest starts at 1900z.
UPDATE 1923z: As I have no 4m antenna I tried 4m SSB receive with my transverter and a variety of antennas. Best DX was a station in IO82 square.
I know 4m is unlikely to be "open" as much as 10m, 8m or 6m, but there should be several Es openings into Europe. Using my transverter, this should allow me some 4m Es QSOs, especially with FT8.
See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .
Jason (in a comment on an earlier post) may well be correct. I was puzzled why the FT817ND was flagging "HI SWR" when I went to TX on the 4m transverter.
Somewhere way back in the mists of time I did do a mod to my original FT817 to add 5V to the RF line from the rig. Of course, this is not there on the FT817ND, so the relay will not switch over to TX.
At some point before the next Es season, I must do this mod on the FT817ND. I cannot recall what I did, so I shall have to photograph and copy exactly the original mod.
As it stands, I can monitor on 4m, but not TX.
I guess an RF detector could be added to the transverter to switch on the 5V TX. This would avoid the need to doctor the FT817ND inside.
UPDATE 0830z: Anyone know if the 5V TX is present on the RF connector of the unmodified IC-705? If so, I could just use the IC-705 with the 4m transverter instead! Guess I should just try it.
UPDATE 0838z: Tried it with the IC-705 Still high SWR, so guess +5v not there either. Pity.
UPDATE 0852z: Just found this from when the transverter was first designed and made, " I also did the FT817 DC switching mod to put 5V DC on the antenna pins when on TX. It was easy to do, with care, and made the transverter switching so much easier. Don't understand why it was not there as standard for the sake of 1 capacitor and 1 resistor."
UPDATE 1714z: If the mod is within my capability, I shall do the 5V TX mod. I must note that I should use the front BNC for 4m.
Yesterday, I tried my 4m QRP transverter on TX with the FT817ND. It said "HI SWR" on the FT817ND. Not sure what was going on, but it is probably something simple, like a dry joint.
I was very pleased with the results yesterday on 4m FT8 RX with just the 40 MHz antenna.
If the fault really is trivial, I am undecided about the erection of a 4m halo. Such an antenna would give me access to 4m.
Some days ago I asked the RSGB's VHF manager what frequency I should use on 4m for FT8 .
Several days later (after I had already found out) I was given the wrong frequency. It was obvious he didn't know!!
You would have expected the VHF manager of our national radio society to have known.
Basically, I was not very impressed.
At one point I was going to take down my 8m wire dipole over the winter and put up a 4m dipole in its place. I gather 4m activity is quite low outside of the Es season, so I may not bother. I suppose I could give the UKAC activity sessions a go.
Yesterday, I spotted 2 stations on an unresonant 8m wire dipole antenna, so I know the RX in the transverter works. It seems pointless erecting an antenna just for the 4m UKAC sessions.
UPDATE 0752z: It occurs to me that I can test my 4m transverter TX by adding a 10dB attenuator in line with my 8m antenna. I have yet to calculate how much the SWR will be improved, but it will be a lot. Even with 10dB attenuation I am sure I can be picked up 3km away! Once this is done (assuming the TX is working!) I can decide what to do about a 4m antenna. Maybe I should erect a 4m halo below the V2000? For this, I would need help as it involves ladder work. Luckily it is above the flat garage roof, so very little ladder work would be needed. I must look for a source of 4m halos. At one time Moonraker sold them.
UPDATE 0808z: Several sources of 4m halos. The going price seems to be a bit under £45.
UPDATE 1658z: 5 stations spotted today on 4m FT8 with the low wire dipole cut for 8m (totally unsuitable) with the furthermost being GM4CXM (507km). Amazing.
Andrew G6ALB is remaking his 4m personal beacon at the weekend so that I can retest the RX in my transverter. The transverter has not been used for years.
I was hoping for suggestions about where to put my RX for the best chances on FT8 RX. Some say 70.100 whereas others suggest 70.154 MHz USB dial. At the moment I have no 4m antenna so cannot TX.
As the chances of Es are much diminished I guess most propagation will be inter-G. I have no idea what activity levels on 4m are like. If like other VHF bands, I guess my best chance will be the next UKAC activity session in 3 weeks' time.
So, where is the best place to watch for 4m FT8 activity in the UK please?
UPDATE 1018z: I have divided my time between the 2 frequencies I know about, but nothing yet spotted on 4m FT8 RX. I am still waiting for FT8 frequency information. Help!!
UPDATE 1107z: I have been told most 4m FT8 in the whole of Europe including the UK is on 70.154 MHz USB dial, so that is where I shall monitor. Still no spots.
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.
See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .
A local amateur has set up a personal beacon on 4m. He is about 3km away. I have no 4m antenna, so I tried reception with the V2000 vertical omni antenna and the 2m big-wheel omni antenna. Good copy was possible despite the power being only 10mW.
Back in the 1960s at university I worked ZB2VHF on 4m AM with 4W and a ground plane. At this time there were very few countries on the band. In 1971, I went /P in a 4m contest.
Several years ago I made a QRP transverter for 4m that appeared in SPRAT (shown in photo). I have no antennas for the band, but a local has made a personal beacon, that I shall try to copy. It produces 10mW. He has a vertical colinear for the band.
See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .
4m is increasingly popular on modern rigs as the band is now widely available in Europe. When I was first on the band in the late 1960s there were very few countries on.
This transverter may give you some ideas for a winter project. It is well capable of reaching many European countries by SSB in the Es season. I am sure it can be improved.
See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .
It is some years since I have been on 4m. There are now far more countries on the band many within Es range. The last time I was on the band I used a homemade transverter. This design was in GQRP SPRAT.
See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/4m-transverter .
Certainly until last year there was a website dedicated to the 4m (70MHz) amateur band. A casual Google search failed to find it. It may have gone?
It is many years since I operated on the band, but I can imagine it is an interesting allocation, especially in the Es season with so many countries now active and more rigs with 4m coverage. A few watts of SSB (or even FM) to a wire dipole should be enough to work many of the European countries now active on the band in Es openings.
UPDATE 0853z: See Colin's comment. It is still there. www.70mhz.org .
In Es openings, many European countries can be worked with simple antennas and low power. One possibility is my simple transverter.
See https://70mhz.org/ .
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