Saturday, October 31, 2020

#10m FT8 Sat. 31-Okt-2020

 I checked 10m and found the band open already early in the morning. I decided to leave the radio/computer on 10m today. Several from VK are received and I even made QSOs to Indonesia and India.

The 10m band is certainly more open compared to last year. I know it is just a snapshot but last week the 10m band was open every day. Something that didn't happen for a while...

According to the Sunspot Index and Long term Solar Observations (SILSO) site the number of sunspots has been rising since the start of this month. The new suncycle has started.

Wednesday, October 28, 2020

Balun musings (2)

 After my doubtful experiment with the PA0FRI 1:4 airwound balun I decided to make the balun shown at DH1TW's site. Just because I had a mix#61 ferrite core still in my "junkbox". And because I wanted to see if I could measure it with the basic test. I also found two 100 Ohm resistors you need to test the thing.

It is my intention to use a balun between my vertical on top of my tower and the CG3000 autotuner at the feedpoint. I don't expect to get a better signal at least that is not my intention. What I would like to see is a better noise/signal ratio and a better and faster/better SWR match on some bands.

This is the basic balun test:

Basically you need to make a test clip from the outer side of the analyser (earth) and measure points A/B/C. The resistors are half the value of Zout. That will say two 25 Ohm resistors for a 1:1 balun or 100 Ohm two resistors for a 1:4 balun.

If you have a current balun, like the PA0FRI balun, the SWR should be low on all 3 points. 

If you have a voltagebalun like I made the SWR should be high(er) on points A/C and low on point B.

A second test for the  voltage balun is to connect the resistors in parallel and touch bot output terminals, SWR should be very low.


The 1:4 voltage balun closed with 2 resistors of 100 Ohm in series showed a SWR  of 1:1,3 to 1:1,6 just like shown in DH1TW's diagram.

First test with clip to A/B/C:

1,85 MHz A:8,4 - B:1,3 - C:5,7
14.2 MHz A:1,8 - B:1,3 - C:1,8
28,5 MHz A:1,9 - B:1,6 - C:1,8

Second test with clip and parallel R

1,85 MHz 1,6/1,6
14,2 MHz 10,3/7,5
28,5 MHz 10,3/10,3

So what does this tell me? Well, I guess the balun is working! Is it good enough for my use? The second test with the parallel R shows quite a high SWR on higher bands! Only a VNA will show correctly I think. I really think I'll order a nanoVNA in the near future.

Now, those that are experienced building these kind of baluns will tell me that you need a #43 kind of ferrite. And yes they are probabely right. But not between a antenna tuner and a vertical that is. G8JNJ has described some tests he did using a 1:4 ruthroff design balun between autotuner and antenna. According to him such a balun will give unpredictable results due to self resonances. Best is to use a balun on #61 material. Other possebilties are a 1:1 current balun or no balun at all on the output of the tuner. With other words I have to experiment...

Last post about common mode chokes has resulted in many comments. As expected because everyone knows best or can tell something about CM chokes. Though there are not many that actually have (good) results with it in practice. John MW1CFN gave me another diagram/example of a guanella current balun with 2 times a #61 ferrite ring. This is not a choke but a transformer and balancer, it forces equal currents in both sides of the antenna but isn't a simple 1:1 balun doing the same?

Now, I've done a bit of reading about baluns and chokes lately. You can find much about it on the internet these days. A real eye opener was the page of DJ0IP.

I like his view on things as written on the first page of his site:

- IMO, no other area of technology is so vastly misunderstood as Baluns (and RF Chokes). The web is full of all kinds of misleading and/or wrong information on this topic.  
- I am still learning and sharing what I have learned.  A major part of my learning process is building and testing baluns in real antennas, NOT modeling or theorizing as most other "would be" experts seem to enjoy doing!

Slowly I come to the conclusion that a single choke/balun will not cover the entire HF band like I want to have for my multiband vertical which works from 1-30 MHz! I do not know the impedance of the antenna on any frequency at all and so a 1:4 balun will not be safe for me to use. Best is to use a 1:1 current balun or actually multiple baluns with different specs to cover the entire HF.

Tuesday, October 27, 2020

#CQWW DX SSB contest 2020 - breaking the barrier

Event: CQWW DX SSB 2020 
Section: Single Operator Low Power All Band 
Logger: N1MM+ newest version 
Station: Icom IC-7300 100W 
Antenna 1: Multiband Inverted-V 2x20m ladderline fed, apex @12m
Antenna 2: Multiband vertical @16m used on 15m/10m 
Antenna 3: 4 element LFA for 10m @14m

This CQWW contest was the first time I was breaking the 1000 QSO barrier. Never, even not in the cycle maximum, have I made so many QSOs in a contest before. It was great fun and all 6 bands could be used. Never expected but I even made some QSOs with USA/Canada on 10m. Remember we are just past the sunspot minimum, if you believe it! 

It was great fun and due to the excellent propagation it was difficult to choose the right band. So my strategy was to stay as long as I could on the higher bands 10m and 15m before propagation was over. It was astonishing to receive Brazilian stations on 10m with 59+! But also on 20m I received USA/Canadian stations with 59+ like they were locals. I really worked great DX although I missed some as well. I did hear JA stations on 40m and 20m but could not work them, same for a few VK stations. Well, you can't have everything.

Not all QSOs displayed, only per DXCC. Green is 10m. Lightblue is 15m.

Monday, October 26, 2020

Last time ZL on 60m

 Although I was participating in the CQWW SSB DX contest I took one hour off the contest especially to work ZL stations on 60m for the last time Saturday morning. Others did as well, it was very busy on 5362 KHz FT8. First contact again was with ZL4OL. But also had QSOs with ZL1MTO, ZL2CC and ZL2LW. For a short moment I had a try on SSB on 5353 KHz with ZL4OL, he could hear me clearly but I didn't hear him. Too much noise on 60m. I really need a separate receive antenna for that band in te future. Hopefully ZL stations will have the 60m band access back in the near future.

The busy 5362 frequency had a bad side effect. A few did try CW but unfortunately had a lot of QRM from the FT8 "gamers". I feel sorry for them as I didn't notice any CW signals, I only read it on social media afterwards.

Friday, October 23, 2020

Last chance to work New Zealand on 60m

 I noticed my last 60m contact from last week was with ZL4OL. Now, it is no hot news but tomorrow is the last day New Zealand HAM operators can be active on 60m. 


 Unfortunately the New Zealand Defence Force (NZDF) has advised us that they are not willing to approve another renewal of our 5 MHz trial allocation/licence.


Very unfortunate since I know there are some operators that have contact with ZL stations every day. It seems that there is also scientific research been done, but I'm not shure what and who has been doing it. Hope to read or hear about it soon.

If you like to say goodbye on air to our friends in ZL or try for the last time to make a QSO with ZL on 60m you better try it tomorrow (24th of October). There is a 13 hour time difference between NZT and UTC. So if I'm not mistaken they have to cease transmissions on 10:59 UTC. Most contacts from Europe to NZ are made on 5362KHz FT8 between 5-6 UTC.

#CQWW DX SSB contest this weekend

 Unfortunately we had to cancel our multi operator event we do the last couple of years with our PA6AA crew. This due to Covid-19 of course. Luckely we can have fun in the contest individually. Hope to hear some of you in the contest this weekend!

Wednesday, October 21, 2020

JARTS RTTY on vy low power

 I've been active on 40m quite a lot last week. Experimenting with JS8Call, since I want to find out what interesting use it actually has for me. At the end of the week some complaints from neighbours came in. Loosing internet connection, others lost TV and telephone line. Of course, with a large tower in the backyard, you're a suspect. Especially when the internet company service engineer is telling that my transmitter is probabely the cause of all misery. The problem is well known and is related to the sensitive VDSL2 modems/line. Placing HAM band notches from the provider site will solve the problem as it did 4 years ago at my own home.

I decided to do the JARTS RTTY contest with very low power (20W) just to not cause RFI. If everything goes well the problem will be solved this week just before this weekends CQWW SSB contest.

With 20W it takes certainly a longer time to get some stations in the log. But with the excellent setup the IC-7300 offers I was able to pick some DX. Congrats to them for picking up my tiny signal. And yes, I heard quite a lot of other DX but it is really hard without 100W. In the end I worked 154 QSO's and 40 DXCC.

I also decided to do some maintenance to my tower/antennas. I removed the 4/6m yagi for the winter. It will be in the mast again next year. I also installed the 60m band sloper again. In the contest I made some contacts on 20m with the 60m band sloper since it received very well on that band....I was surprised. It did much better as my all band vertical on top of the mast. Especially to the USA in which the direction of the sloper is. I'm now thinking about adding wires to have a multiband sloper.

The "naked" boom ready to store in the garage.

Monday, October 12, 2020

CM choke, RF choke, RF isolator, line isolator, RF current filter

 Years ago Hans PE1BVQ was so kind to give me a common mode filter. It was at the time I had issues with my VDSL2 connection. I tried everything to avoid the coax from radiating and receiving unwanted signals. However, the CM choke didn't solve the problem. It was solved by someone else placing software  with amateurradio frequency notches in our VDSL2 modem.

Personally I never had any good results with CM chokes, not the results showing in this videos:

Of course it is all a matter of how much common mode there actually is present on your coax lines. If you haven't got it the difference will not be so obvious as shown in the video. 

I got 2 common mode chokes, the one from PE1BVQ with a unknown ferrite but probabely it is mix #43 material? The other one is built by me, it uses a 4C65 ferrite. I always left the balun from Hans in my coax line to the vertical but does it really help, I can't say. I tried to test and see any differences in RX and TX but it isn't detectable. I guess I have not enough common mode (lucky me!). 

The question now is, do both common mode chokes work? I haven't got expensive VNA (Vector Network Analyser). I know the nanoVNA is cheap but haven't got that as well. I got a digital multimeter which worked, but went defective just when I wanted to use it for this experiment. So what is left is a cheap 6 euro multimeter. I came across a nice diagram from a CM sensor, it looked easy so I build one. However due to other distractions I didn't read well, I assumed I had to measure current so I choose mA to do the test. Imagine it gave some strange readings, I was confused. Discussed it on a dutch HAM forum and then I saw my fault...I should choose mV. The current is rectified and you measure voltage over the resistor which is in parallel with the meter (not drawn in diagram). Anyway, it gives better readings now.

But what to measure now. What should I measure? I asked again in the dutch HAM forum and PA3DJS was so kind to tell me that you should measure without the choke first to see any difference. When connected both in/output should read almost no difference, but of course lower readings as without the choke. 

Well, this is what I measured in the end:

Input 10W FM on 5365KHz

Without CM choke: 450-455 mV on several places on the coax

With PE1BVQ choke: 230 mV on several places on the coax. Near the choke input (TX side) 3 mV and near the choke output (antenna side) 6 mV

With PE4BAS choke: 240 mV on several places on the coax. Near the choke input (TX side) 94mV and near the choke output (antenna side) 47 mV

Interesting to see that the chokes obviously work. Would be nice the see how much dB they actually surpress. I haven't got the equipment and knowledge for that (yet). I guess most average HAMs don't have that. But the CM sensor is easy to build and a nice experiment to see if a choke actually works.

There are many ways to build a CM choke. Interesting to see so many designs, some working well, some working just good enough. It looks like there isn't a design that is really the best. To have proof that it really works and has enough CM surpression you really need a VNA.

Videos I really like to see, if only it was for the funny accent, are those from TRX bench on this subject. The way Peter tells about the CM choke or 1:1 balun is really understandable, you learn a lot about this subject for shure.

This really was a nice experiment and wish I had more time to experiment with these kind of homemade filters & transformers. No doubt I will learn a lot from it...

Recent article on PA3HHO Pleun's blog:

Sunday, October 11, 2020

JS8Call use

 Once or twice a week a take a look around on JS8Call. Just to check if I got messages or put my QTH on I always try to start a QSO but though enough stations are on the air not many respond. Yesterday I saw someone testing with APRS messaging, I thought to give him a call transmitting the test was received and we started a QSO. It was with G0CQZ Nigel and we had a nice conversation going on. But I have to say that was after trying to have a QSO for over 30 minutes. I know....not everyone has that patience, most are doing other things and just monitor JS8Call. In the past I was a fanatic packet radio user, I wrote and received multiple messages every day with various people. Checking for messages on JS8Call however is most times not neccessary, there are non! Besides that I check other JS8Call frequencies as well but 40m seems to be the most interesting...

So I asked myself what else is a interesting experiment to do with JS8Call?

- Write someone a message

- Write yourself a message to retrieve later (at least you finally have a message then ;-) )

- Relay your own call back to yourself

For the more advanced users:

- Try to relay a message to another continent.

Actually do you know interesting experiments that can be done with JS8Call? I know it is intended for chatting but not many do actually so we should have something to do with this very versatile digimode software.

Please let me know in the comments, or better. Try to send me a message via JS8Call. I can see OH8STN and EI2GYB most of the day so you could store a message there if possible. It would be great to finally receive some messages. I will reply of course.

While writing this post I had a QSO with SP3IEW Arek:

We tested fast and turbo mode as experiment since signals were strong. Great fun and turbo mode is almost as fast a chatting with whatsapp or messenger.

Interesting links:

Wednesday, October 7, 2020

Operating mode comparisation chart including FST4

 DB6LL Hartmut made a very nice comparisation chart which he published on facebook. I got permission to publish it on this blog to inform even more HAMs. Thank you Hartmut!

I still have to try this new digimode. I think it is interesting to actually see digimodes developed that can compete with the sensivity of WSPR. If you look at my previous post what is reachable with simple equipment 5W and a small antenna, with FST4 you can actually make a real QSO worldwide.

7-Feb-2021 Updated chart after discovering an error 

Monday, October 5, 2020

I was wrong....portable WSPR results

 I was wrong assuming I had no spots transmitting one slot after my unsuccessful participation in the POC yesterday. Although I programmed WSPRwatch with the call PE4BAS/P I probabely transmitted PE4BAS only (a glitch in the software?). By coincidence I checked WSPRwatch on my iphone today when I saw my signal was spotted after all...

I had similair results in the past with 5W and the superantenna MP-1 setup. It is always a surprise that such a small antenna does so much magic. The nice thing with this setup is that I don't need a tablet or computer to transmit WSPR. Only the WSPRwatch app on my iphone will do.

When weather is good I certainly want to try this setup at the coast near the sea. Setting up the station to do some WSPR transmissions will only take 5 minutes. Same for breaking down. I could do a complete experiment in just 20 minutes. It takes longer to walk to the water and find a suitable place for the experiment.

Sunday, October 4, 2020

Fox Mike Hotel Portable Ops Challenge review


Go pack...
 This new challenge is kind of a contest and a try out. I planned to participate on/off for 8 hours at sunday in the most difficult section portable SSB.

 The weather was not good, rain and a lot of wind. So instead of going out I stayed at home and setup the radio in the glass house with the Superantenna MP-1 just outside on the grass. A easy and compact setup. I installed VKCL log on my notebook. I've been active from around 9:30 till 11:00 UTC but only heard a few stations on 40m and 20m. Some of them calling in the RSGB contest and some in the TRC contest. But I didn't hear anyone making contacts in the Portable Ops Challenge. After 1,5 hour listening and calling I didn't make a single contact. I decided to try some WSPR with 5W but even that didn't result in any spot. Well I then decided I would exchange the portable for QTH section to see if I could hear/contact stations from the home base. I dismantled the portable station...

The station...

So back at home I tuned over both 40m and 20m, but unfortunately didn't hear anyone calling in the POC. Probabely this is more a American party? There was enough promotion on the internet and in magazines, there is a website and a lot of information but it looks like no one bothers? Or others have given it up as well after not hearing anyone calling?

While thinking about this "contest" and writing about it in this blog something else came to my mind. The complexity of the exchange....

From the POC rules and scoring:

"Contact Exchange CALLSIGN, Station class (Q or P), running contact serial number starting with 1, 4-digit Maidenhead locator."

Superantenna MP-1

It occured to me that this is way too complex. I would like to give the organisation an advice to look at the rules in the UKEICC contests in which the exchange is just the 4 digit maidenhead locator. Why should the opposite station know a serial number? I can see the need for a Q and P since it is part of the scoring, you could use callsign/P if portable to let others know instead of keeping it part of the exchange. However it is still difficult to work stations in other contests with these exchanges, you have to explain your goal and the exchange you need. It costs time other contesters don't want to spend. Another set back is that you can't use FT8 with these kind of exchanges...if we could use FT8 for digimode operation the challenge would be a lot more populair. Using only the 4 digit maidenhead QTH locator as exchange would solve most problems I think...

Personally I think the people that organized this challenge did a good job. It is well thought over and a very noble thought to give portable stations a equal chance in this contest. However most contesters have large antenna arrays and a lot of power, that's the way they play the game. They are not used to pick very weak signals out of the ether and not used to get out with only modest equipment. Even though this is a fun challenge. I wrote about RaDAR in the past, a fun challenge as well but not very populair. So unfortunate that there are some very good ideas around but there are just too many activities every weekend and even through the week that are much more appealing for the average HAM contester.

Thursday, October 1, 2020

Balun musings


 For a while now I'm thinking about a coax wound airbalun to feed my vertical, in between the autotuner and the antenna. The design is made by PA0FRI and therefore sometimes called the PA0FRI balun. The main advantages: It's cheap and easy to make, it cannot become saturated. It is not a balun like the commercial ones you can buy. In fact it is a HF transformer, it transforms from unbalanced to balanced. I studied the website well and decided to make a switchable balun 1:1 and 1:4 ratio since I don't know the impedance of my vertical antenna system. What I overlooked is that the transformation ratio is only working for a real ohmic impedance, besides that it seems the lengths of coax on the balun have a influence on the impedance especially when they are relatively long compared to the wavelength. This is exactly what happened when I tested my prototype balun (I didn't know that before but learned from other wise men). 

I actually was surprised about the measurement results above 18 MHz. But if I had a better look on PA0FRI's page I should expect it. actually PA0FRI build a smaller balun to overcome a problem on the higher frequencies. Not shure though if this is a improvement of my antennasystem if implemented. Only testing it real time will give me a impression of how it is working. However I was not shure if I made the balun right and desoldered the relay to test the balun at 1:1 position, it was a disaster and not what I wanted to see. With 50 Ohm at the antenna side of the balun I couldn't see 50 Ohm on the other side, not on any frequency. I realize I don´t use 50 Ohm but 75 Ohm cable, could that be a problem. But my analyzer only does 50 Ohm measurements so how can I test if the balun is ok? Searching on the internet I came to the conclusion that measuring a balun with a MFJ259 is difficult. Especially if you want to construct a wideband version. The way I tested the balun is a improper way and gives a faulty impression. W8JI gives a very basic balance quality test example (find it in the MFJ259 manual as well!). However it is very basic and tells the balun is working though not what quality it is. A 1:4 balun also shows a phase difference in signal that can only be measured with a scope and signal generator. I don't have that kind of equipment as a simple hobbyist so building a proper balun will be difficult or purely experimental.

  So I'm re-thinking this whole balun concept. I probabely see it all in the wrong way, but something or someone has to open my eyes. 

I might try a compact design like the one DH1TW made. It fits in a small box and is easier to fix high in the tower between the vertical and autotuner. Besides that I still got a FT240-61 ferrite ring in my "junk" box somewhere. However I have to rely on his test results since I have no proper gear to measure it.

Yes I can buy a pre fabricated one at ON7FU. But what is the fun of that....

Another balun, or transformer project has been repaired. Remember my beverage efforts in 2019? Well, I was very enthousiastic about the results when suddenly it came to a stop. I presumed it was the rain that was terminating the fence and suddenly I didn't have good results anymore. Even when it went dry the results were not that good as before. Now I know why. One of the transformers smelled. You know that smell from burned isolation...I finally had some time to look closer and disassembled both transformers. Both were showing burns, you can see it on the wire on the photo, the light parts of the wire have no isolation on it anymore. I can't remember but I probabely transmitted on the beverage coax by accident "blowing up" both transformers. I have repaired both now and have some other experiments in mind to use them. I really have to be careful though to not transmit at all. I've been thinking, if it happens again, I will replace this "coated" transformer wire with thin wire and decent thicker isolation.