2024-03-11

Fault in the 23cm Antenna System.

There seems to be a fault in my temporary 23cm antenna system.

The signal disappears intermittently, and I suspect a fault in the connector for the cable bypassing the rotator. I have ordered better cables and N-connectors, so as soon as possible that cable should be replaced. Another option could be intermittent voltage to the preamplifier from the radio (IC9700), but the cable/connector fault is the most likely.

I will need to get some assistance from some local ham(s), as the antenna should be mounted about 2m higher, still in a temporary position. I cannot do that alone. The risk of damaging the antenna is too high.As the antenna is standing in my backyard and surrounded by houses and trees, every meter in height will help, so it will be interesting to see how much the signals will improve.

At a later stage I epxect to mount the antenna in 8-9m height. That is what I can do here. There will still be trees in the way in some directions, but it should be above houses in most directions.

2024-03-08

Intermistic 1296MHz Yagi Setup.

The past few days I have worked getting a bit of activity going on 1296MHz.

The antenna is a Flexa Yagi model with 16 elements, for mounting behind the reflector.

The mast at the moment os just some military stackable pipes, and I could not handle more than 4m length alone, so that is the height of the antenna right now.

Results are varying. A station about 20km away could not hear my 5W at the antenna. He is in a poor direction, as the signal has to pass through my house, so maybe not too surprising.

We have had a bit of tropo propagation, so the beacon in Kiel, about 200-250km away is quite strong. In that direction the antenna points over free fields, and at the moment the signal from DB0VC is S9. During the day it was audible at all times. 

I do have a preamplifier near the antenna, so reception is quite decent.

At a later stage the antenna can be mounted at about 8m height, but the results are encouraging.

I did try to send a few CQs on 1296.200, but no replies. 

In the SE direction I can hear very strong radar signals, S-meter shows up to s9+30 in the peaks.

Next step will be getting the antenna higher up and see what happens. I will need assistance from some local hams, so it may take a little while.

2024-02-18

A Bit of HF Activity.

 Today I put my first HF QSO of the year in the log. I didn't do much last year either, due to other commitments.

Today I made one of my forst QRP SSB QSOs in years. Some local stations had goe to Greenland and they have been quite active.

When they were reported on 18MHz I tried with just 5W SSB form my IC-705, even though the signal was not very strong. Much to my surprise OX7AKT came back to my call after one or two times, and we made the QSO. It is extra fun to do that with just 5W SSB and a half wave vertical.


2024-02-08

More 8m Activity.

 Since last entry the solar activity dipped a bit and came back up. 

There were a few days without signals decoded, but a few came through.

PJ4MM Several days

ZS6OB and ZS3/V51PJ one day

The setup is still the IC703 and the 10m half wave vertical.

I am still running my 6m monitor, and I get European signals every day.

I need to expand the setup to 10m, and to more VHF (and UHF) bands.

Let the monitoring continue.

Update: ZF1EJ also came through today.


2024-01-31

PJ4MM on 40MHz Again Today.

 Another good day for the 40MHz band.

One more time PJ4MM was coming through with up to 0dB S/N. 

It will be interesting to see how the 8m band monitoring will turn out this spring.

2024-01-30

Monitor on 8m (40.680MHz)?

 I made my first test, listening on 40MHz. There is some experimental work going on on  40.680MHz with weak signal modes.

A local station with indoor antenna reported decoding PJ4MM, so I started testing

So I had my IC-703 connected to the 10m half wave antenna, and set the frequency. Pulse noise up to around S7. The noise blanker (NB) of the 703 seemed to make little difference. I tried to get the NB setting, and set it to the highest level. That reduced the noise, even if it is still not good. No S-meter reading.

Then PJ4MM came up on screen, starting with a S/N of -20dB, and for about 20minutes of the signal was there. Best S/N has been -7dB until now.

Not a bad beginning, given the severe pulse noise. DX heard on 8m.

Right now I am not going noise hunting, it is still winter time, and I have a cold, or the flu. In the spring I may try, and along with that, maybe try to make some phasing out of that noise. After all, it's only a single "channel" I need to cover. 


2024-01-22

10GHz Transverter, Continued.

 In the autumn/fall last year I was out making a receive test of a 10GHz transverter briefly described a few days ago in the previous post. 

When I should have had a signal from the OZ7IGY beacon about 25km away, there was ... nothing.

I started the fault finding with a measurement of the LO module, and it did look pretty good. So Now the down converter should be tested.

I located a signal generator (low cost Chinese circuit with the ADF 5351 synthesizer. As the signal generator has a fixed output, I made a small loop for 10GHz, soldered to a low cost (chassis) SMA connector. Measure on the spectrum analyzer (with built-in frequency counter the signal generator seemed to stay within a few 100 Hz, with a fixed offset of about 10kHz. Good enough for a first test.

Power up the transverter with 12.5V, the IF connected to a Malahit DSP2 SDR set to 144MHz, and let the system warm up a bit. The 12.5V was about what the battery delivered at the test. 
It sounded absolutely dirty, with some irregular jumps in frequency.

Where was the instability? I tried connecting the FT-290 and it was the same. Apparently I could eliminat the possibilty of the Malahit going faulty. Now remains the LO of the transverter or the signal generator.

Next test was, let us see what happens if the supply voltage is increased.

Bingo. at 13.5V the LO apparently jumped to the correct frequency (well, about 3kHz low) and stayed there, the tone sounds good, all the dirt gone from the audio, and the sensitivity looked much better. You may laugh, I don't mind, because I foind the fault.

Connecting back to the Malahit SDR, and it looked good.

The Chinese signal generator, though has a rather noise output. Good enough to test the system, but the phase noise is atrocious, only about 10-20dB below the carrier. I heard that a ham not too far away has made some modifications, and I will look into that.

So what to do when I do go out into the field? I need 13.5V and the battery delivers only 12.5V. Too low for a good function.

I think I will try first with a different battery and a DC/DC converter. I know that the DC needs extra filtering, but it should be usable for the first field tests. Next step: check the TX function.