We like to do a circular walk around the village of Dalham near Newmarket. This is the lane back to the village. Delightful.
5 Mar 2023
Dalham - NOT amateur radio
We like to do a circular walk around the village of Dalham near Newmarket. This is the lane back to the village. Delightful.
Ferrite rod TX antennas
Ferrite rods are commonly used as RX antennas on MW and LW. They are compact and efficient for their intended purpose. Their use as TX antennas is almost non-existent.
As long as the ferrite is suitable for the frequency and as long as the ferrite is not in saturation, they may be used on TX. This implies very low power, but we know on WSPR and possibly FT8, long distances may be spanned with very low power indeed. Certainly great ranges have been covered with milliwatts and microwatts.
Some years ago, I did some TX tests with ferrite rods and the results surprised me.
In absolute terms, I have little idea about their loss compared with, say, a dipole. At 630m and 160m, antenna efficiencies are often -30dBd or worse, so they could be far better than we might expect. They certainly are small! Some people have bundled several rods together. I have not tried this.
This is yet another area in which radio amateurs can carry out useful research. Be careful that the ferrite rod alone is doing the work and you are not coupling into a bigger antenna nearby.
In my view ferrite rods "compress space" within the rod. As such, they could be used as magnetic or loading in E-field antennas.Remeber to keep power very low.
See https://sites.google.com/view/g3xbm4/home/antennas/ferrite-rod-tx-antennas .
8m QRP FT8 (Sunday)
At 0925z, my 8m QRP FT8 was turned on. For a change, I am TXing 2nd. So far, no spots.
UPDATE 1100z: SP5NOF (1406km) and G9PUV (158km) spotted, but nobody has spotted my 8m FT8 QRP. I hope SP5NOF is legal.
UPDATE 1801z: No further spots all day. QRT soon.
Spring? - NOT amateur radio
The birds in our churchyard are getting ready to nest by repairing old nests as the photo shows. Next week could be much colder. They are in for a shock!
10m QRP WSPR TX (Sunday)
At 0925z, my 500mW 10m WSPR was turned on. So far, no spots.
UPDATE 1021z: 13 spots of me from the Canary Is.. Some reports have 22dB in hand, suggesting I could have been copied with just 5mW (or lower) if the RX noise floor was low enough. On previous days, signals have been even stronger at times!
UPDATE 1150z: LA3SP (1049km) has spotted me many times with up to 25dB in hand!! 3 unique stations have spotted me so far today.
Wisdom - NOT amateur radio
Many years ago I read somewhere that there is a great deal of difference between being clever and being wise. My Auntie Kitty was definitely not clever, but she was wise.
This quote was in "The Knowledge" yesterday.
At the 1937 Soviet writers’ congress, Boris Pasternak, author of Doctor Zhivago, faced a terrible dilemma: to speak or not to speak. This was at the height of Stalin’s purges; writers who deviated an iota from the regime’s view risked being “disappeared”. On the final day, more than six feet tall and “incredibly beautiful”, Pasternak went to the lectern. The silence, it was said, could be heard “all the way to Vladivostok”. When he finally spoke, he began with just one word: the number “30”, denoting Shakespeare’s famous sonnet. “When to the sessions of sweet silent thought / I summon up remembrance of things past…” All 2,000 people in the hall rose to their feet and recited the rest of the poem by heart. The sonnet “said everything” – you can’t touch what we hold in our heads.
4 Mar 2023
Sub 9 kHz DX
Some years ago, I was quite keen on amateur radio below 9 kHz. I well remember people saying it was a waste of time and nobody would get beyond the garden fence. How wrong they were!! Some quite remarkable distances have been spanned.
Although for radiated DX below 9 kHz very big antennas are needed for TX, on RX some tiny antennas can work perfectly well such as an E field probe which is tiny. What is needed is very high stability and very narrow bandwidths, usually achieved by locking to a VLF MSK signal or GPS. Some years ago DJ8WX was spotted by locking to a VLF MSK signal (see photo). All this was possible with free software. Sometimes it is necessary for signals to be integrated for hours or even days.
It is some years since I have experimented at real VLF.
8m QRP FT8 (Saturday)
It is now 1625z and I have been on 8m QRP FT8 for about 30 minutes. So far, no spots.
UPDATE 2025z: QRT now. No spots all day.
10m QRP WSPR (Saturday)
When we got back from Peterborough (at about 1550z), I turned on my 500mW WSPR beacon. So far, at 1620z, 5 spots from the Canary Is..
UPDATE 1745z: 6 unique stations have spotted my 500mW WSPR today.
UPDATE 2026z: 11 spots of me today with 9 transatlantics.
Subscribe to:
Posts (Atom)
