XBM80-2

 

Yesterday, I posted the 10m Lesser Chirpy. This was based on the 80m XBM80-2 QRP CW transceiver which is shown here. 

You would be hard pressed to make this transceiver much simpler! Do not be afraid to experiment - I am sure you can do better. 

S1 provides offset between RX and TX by shifting the crystal frequency, how much will depend on C1. You could always make C1 adjustable so the offset is what you want.

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

CDARC 80m net

As an experiment I tried to join the CDARC (Cambridge club) 80m net this morning with my 2.5W and the earth-electrode antenna. Although I had no problem hearing people, I could not be heard. My noise level is very low on this antenna, but I needed more power to overcome noise others were probably suffering. 

The SWR is too high for the auto-ATU on my FT991A. It just says "High VSWR" and gives up. On the FT817ND it works fine.

80m FT8 RX with the earth-electrode "antenna" in the ground

Since connecting up the 80m FT8 RX yesterday, 1122 stations in 5 continents have been spotted on RX using the earth-electrode "antenna" as the map shows. 

Yesterday, 16 stations spotted my QRP TX too. It certainly works!! 

80m QRP FT8 (Sunday)

For a total change, I am trying 2.5W FT8 to the earth-electrode "antenna" in the ground on 80m.  So far, nobody has spotted me and just 1 G spotted on 80m FT8 RX - G6KUI (136km).

UPDATE 1600z:  G6TEL (233km) has spotted me well on TX and 17 stations spotted here on RX.

UPDATE 1751z: 221 stations spotted on RX with the furthermost R7GW (3240km). On TX spotted by 5 stations with the furthermost being F5PGT (480km). The earth-electrode "antenna" obviously has an SWR just over 3:1 so the FT991A auto ATU will not tune, but the FT817ND is OK still. This odd "antenna" still works fine on 80m. As I have said before, the XYL and neighbours do not even know it is there!

UPDATE 1922z: 433 stations spotted so far on 80m FT8 RX and 15 stations have spotted me on 80m FT8 TX with the furthermost EA1N (1076km) in northern Spain.

UPDATE 2120z:  596 stations spotted on RX in 3 continents. 18 stations have spotted me on TX.

UPDATE 2235z: 660 stations spotted on RX. Now RX only for the overnight period. 

80m FT8 overnight

 With 967 stations spotted overnight on 80m FT8 RX, it was quite rewarding on the earth-electrode "antenna" in the ground. Best DX spotted was NR5R (8276km) near the Mexican border in Texas, usa.

80m FT8 RX

For a total change, I am on 80m FT8 RX with the earth-electrode "antenna" in the ground. So far this evening, 71 stations across Europe have been spotted.

UPDATE 2038z: 231 stations spotted. Apart from 2 in North Africa, all are in Europe, I think.  I shall leave the RX on overnight to see what is spotted.

How simple can you go and communicate?

Some years ago I wanted to see how few parts are needed to make a viable transceiver that really worked. The result was the FETer transceiver for 80m. This appeared in GQRP "SPRAT" magazine and copies were made. G3XIZ worked as far as Switzerland with his!

See https://sites.google.com/site/g3xbmqrp3/hf/feter-80m-qrpp-cw-transceiver

Ultra-simple RX

Some years ago, I wanted to see just how simple a receiver could be made with a decent performance. Later, this was converted into a full transceiver.  For so few parts, it is remarkable.

See https://sites.google.com/site/g3xbmqrp3/hf/regen

80m WSPR with the ferrite rod antenna

In all, 46 stations were spotted on 80m WSPR using the ferrite rod antenna. Just one station spotted my 2.5W. There was far more 80m WSPR activity than I expected.  See table below:

80m WSPR spots with
the ferrite rod antenna

80m ferrite rod TX antenna

After removing the tape, I was able to resonate W5OLF's ferrite on the 80m FT8 frequency. On RX it is copying lots of stations (45 so far) with best a Russian at 3300km.

No spots yet on TX (1W) but I shall keep trying. Both the ferrite and fixed capacitor are cold suggesting the ferrite is well below saturation. The ferrite is just sitting on the shack bench oriented for best NVIS pickup. See photo.

UPDATE 1902z: 211 stations spotted on 80m FT8 RX with the ferrite rod on the shack bench. No TX spots. Power increased to 2.5W. Still NVIS orientation.

UPDATE 1912z:  Changed orientation of antenna to vertical. Still no TX spots. Remember that FT8 is about 10dB less sensitive than WSPR.  Surprised that not a single spot yet received.

UPDATE 2012z:  264 stations spotted on 80m FT8 RX, but no spots on TX (2.5W) so far.

UPDATE 2023z: Switched to 80m WSPR at the same power although I am unsure how much WSPR there is these days on 80m. SWR is excellent.

UPDATE 2100: I am puzzled. I reset the WSJT-X program and copied a DL station on 80m WSPR RX, but this failed to upload to the WSPR database. I am pretty sure that my internet is working. On another site all seemed well. No TX spots on WSPR. HB9AFZ (900km) was a strong -14dB S/N on WSPR just now. Also copied were a couple of German stations. None of these stations appeared, so I am wondering if the fault is at the WSPRnet end?

UPDATE 2124z: Fault found!  I had my callsign with a space behind the last character. When this was removed the RX spots appeared. Still no TX spots, but I am pleasantly surprised by the number of WSPR stations active on 80m.

UPDATE 2230z: Just gone back to horizontal orientation on the shelf above the rig. No TX spots. I shall leave things running overnight. Rechecked the match is best. As I have received not a single TX spot all evening with the antenna vertical and horizontal, I am wondering if my signal is just too weak to be copied in the noise smog that many stations suffer from? If there are any automatic RX stations spotting through the night when noise tends to be lower, I might get the odd spot.

80m ferrite rod TX antenna

Jay, W5OLF has very kindly loaned me a ferrite rod TX antenna that he had been using with 100mW WSPR as a TX antenna in Texas.

Sadly, on a couple of rigs this seems to peak too high in the band. From past experience adding a large capacity across the 50 ohm winding transforms to a much smaller capacitance across the secondary winding. So, I would have expected the resonance point to have shifted LF. I tried a 220pF across the 50 ohm winding but I could not detect an LF shift! The last thing I want to do is alter the antenna itself. At the moment I am puzzled. Maybe the capacitance needs to be much larger. I shall try this next.

If made resonant, I was going to try this on 80m WSPR and FT8.

Some years ago I was surprised how effective a ferrite rod could be on QRP TX.

See https://sites.google.com/site/g3xbmqrp3/antennas/ferrite_tx

UPDATE 1105z: I tried 790pF across the 50 ohm winding and the resonance showed no visible change. I suspect Jay has configured this as a vertical Marconi and not as a conventional ferrite loop. The antenna is encased in heat shrink, so I am unsure of his configuration. Both he and I had assumed a "plug and play" situation!

80m FT8 overnight

What strikes me is how similar results were to 160m FT8 recently. As before, I am still using the earth-electrode "antenna" in the ground. Overall, 769 stations spotted since yesterday afternoon.

80m FT8 RX here overnight

UPDATE 1322z: After remaining on 80m FT8 I was surprised to see a recent CQ (10W) was spotted by 6 stations with best DX spot being by LA7DFA (1311km). Earlier, I called a G station and enjoyed a solid 80m FT8 QSO. I am pleasantly surprised how well the earth-electrode "antenna" in the ground is performing on 80m FT8.

80m FT8 with the earth-electrode "antenna" in the ground

Just for a change I am trying 80m FT8.

At this frequency some may argue that as much energy is radiated by the wire running along the garden fence as is radiated by the "loop in the ground". I cannot be sure.

Anyway, it certainly works. I had to use my FT991A auto-ATU to get a low SWR and I am still limiting power to 10W so my PSU is well within its ratings (20A max).

So far this afternoon, my CQs have been spotted across Europe and I have spotted 77 stations on FT8 RX with best DX R4IK (3218km).

UPDATE 1938z: So far this evening plenty of EU stations spotting my 10W. On 80m FT8 RX 298 stations spotted so far.

Stations spotting my 10W FT8 TX so far

UPDATE 2047z: Now 359 stations spotted today on 80m FT8 RX.

80m FT8 RX so far today

80m chirps?

Southgate News has a report from the IARU about odd chirps that have recently appeared on 80m.

See http://southgatearc.org/news/2019/october/mysterious-chirps-in-80m-band.htm

XBM80-2 transceiver

This was a very simple 80m CW transceiver that I designed and built many years ago, apparently in 2010.

Like all my designs please take this as a starting point as you may very well be able to do much better. As you can see this was just experimental. At the time it was fun. These days, such experimental work is probably beyond me since the 2013 stroke.

See https://sites.google.com/site/g3xbmqrp3/hf/80m_xbm80

80m QRP - the XBM80-2 transceiver

About 7 years ago I designed this ultra-simple QRP transceiver for 80m. It managed some local QSOs. These days, following my stroke, designing and building things is hard.

There is a YouTube video too shown here.

See https://sites.google.com/site/g3xbmqrp3/hf/80m_xbm80

80m FT8 RX

Overnight, I remained on 80m FT8 RX. Basically very similar to the previous night with best DX a Brazilian PY2XU (9584km).

Once again on the earth-electrode "antenna" in the ground was used.  I guess the next band to try with this "antenna" is 40m FT8, although I very much doubt it will be any good up there! Mind you, I thought it would be useless on 80m!

80m FT8 RX this evening

Already in the last 30 minutes alone, stations all over Europe are again being spotted using the earth-electrode "antenna" in the ground. At present the best DX spotted is A45XR (5794km) in the Middle East.

UPDATE 2218z: The first North American spotted on 80m FT8 RX this evening was K1CP (4997km).

80m FT8 RX overnight

Last evening and overnight, I went on 80m FT8 RX using the FT817 with my earth-electrode "antenna" in the ground expecting, at best, mediocre results. The "antenna" was not even well matched and I made no attempt to improve this. To my surprise, it worked remarkably well.  Best DX spotted was PY2KP (9578km).

Stations spotted last night on 80m FT8 with 
the earth-electrode "antenna" in the ground.

UPDATE 1435z: I remained on 80m FT8 RX all day today. I see that 9 stations in 5 countries have been spotted in just the last 30 minutes!

80m FT8 RX with the earth-electrode "antenna" in the ground

This is an experiment as I do not expect great things of this antenna at so high a frequency. Indeed the match is not as good as on 160m and I have made no attempt to optimise this. On the screen I am seeing lots of EU stations, and these are now appearing on PSKreporter.

Best DX so far tonight is RL9L (4017km) after just 15 minutes!

UPDATE 2104z: At the moment 80m FT8 RX is behaving much like 160m FT8 with all over Europe being spotted. As yet, no DX spotted outside Europe apart from the Canary Islands.

UPDATE 2215z: N4DB (6131km) spotted at 2149z. This is the first North American station spotted on 80m FT8 RX this evening.