More 122 GHz success

This "news" is actually not new. It happened in December 2020. I have just received the QSL card from Harry WA0CNS. We have made first ham radio contact on 122GHz between the U.S. states of Missouri and Illinois.

This contact crossed a line-of-sight distance of 7.67km (4.76mile). The atmospheric conditions were not all that great. The relative humidity was still too high:

• temperature 3.6 deg. C

• dew point -5.2 deg. C

• pressure 1005.2 mBar

• humidity 51.1 %

• wind speed 2.4 m/s

Signal from Harry was S9 with QSB to S5. Herbert's signal was much weaker on Harry's side (Herbert uses a 21 dB horn antenna while Harry has a dish).

Contest results

I am not really attending contests to win, more for fun and to test the technology. However, it feels good to receive certificates like this one:

Success with Ham Radio on 122GHz

Harry WA0CNS and myself went outdoors to play with our new 122GHz units (about 500 microW of output power, 19dBi horn antenna on my side) on Saturday, November 7, 2020. We managed to make full contact using CW signals (Morse code) across the distance of 5.2 km (3.2 mile):

This frequency is extremely difficult, signal propagation depends heavily on moisture in the air. In theory, it should work better during winter months. We will keep trying for longer distances!

Some pictures of the stations used:

More details about our attempts on this contact can be found here (click on the link).

73 Herbert

Boys with Toys 2

My last posting was about using my RIGOL Spectrum Analyzer with frequency range up to 1.5GHz to show characteristic of a 10GHz filter. That little test made me wonder if I can use the same Spectrum Analyzer to display a signal in the 10GHz range on that analyzer. Obviously, I have to mix the signal down below 1.5GHz using a transposing signal from another synthesizer.

I have used my 24GHz transverter with 11.88GHz local oscillator, because that signal is conveniently fed to a connector on the transverter's front panel. The same mixer from my previous test (IF range only 0-150MHz) was used for the first test today:

Yes! It really works! My ELCOM on the left side is programmed to 10.805GHz (+13dBm) and the gray transverter on the right side delivers 11.88GHz (+10 dBm). Difference of these two signals is exactly 1.075GHz which is what we see on the analyzer. What we also see is the signal level below -40dBm. Hmm ...

I have tried to "zoom in" and changed the RBW ratio on my RIGOL from 1MHz to 300kHz. Signal still looks nice and clean, just not too strong:

Can we do something about the attenuation? Of course we can. I tried 3 things:

• Find better flexible cables
• Replace flexible cables by Semirigids
• Use different mixer

Luckily, I have bought good sized bundle of these flexible black cables with SMA connectors cheap on eBay. Maybe I could find some better pieces in that bundle? Tried and ... the signal strength improved +30dB:

Wow! This is almost perfect! Maybe Semirigids will make it even better:
 

Hmmm, not too much. Only about 2dB. Surprising, really. These black cables are RG-178 which is OK but not as good as semirigid, at least in theory. Whatever ... let's try another mixer:

Nice! Improvement about 8dB! This mixer has IF range 0-2GHz, but it has apparently been exposed to salty water somewhere. I have bought it cheap on eBay. Lets try better one:

No surprise here, less than 2dB below zero. This mixer behaves as expected. Note that I am feeding it LO signal 11.88GHz about +10dBm and the test signal is 10.8GHz about +13dBm. My RIGOL has internal attenuator of 10dB, so the conversion loss in this case is 13 - (10-2) = about 5dB. That is certainly very acceptable!

My next test will be with a Harmonic Mixer (same thing, but the mixer will generate harmonics from a strong base signal to be able to display higher frequencies, such as 24GHz). But that will be the topic for some other day.

73 Herbert
AF4JF

Boys with Toys

Even at my age of 55, I still feel like a boy when it comes to my electronic (not to mention radio electronic) toys. Especially if my friends keep encouraging me by sending me links to interesting articles on the Internet. Like the document (tnx OK1DXD) where I found following picture:

Nice ... especially after finding dual mixer (two mixers with integrated LO power divider) on eBay:

The seller stated max frequency 18GHz and max IF frequency 150MHz. Well, I overstepped the IF maximum almost 10x and the mixer still worked, so I hope that RF inputs will accept 24GHz.

Now, what to test? Easy pick. I have found a nice waveguide filter on 10567.5MHz:

So, I have located couple of cables, not really suited for 10GHz but at least with SMA connectors, and connected everything together:

Where to get LO signal from? That was easy too - my favorite ELCOM synthesizer provided +13dBm on the frequency of 11GHz:

So far so good ... but will that thing work? I have turned my RIGOL analyzer on and activated the Tracking Generator - and YES, it worked:

Let's try to zoom in to check how steep the filter is:

Pretty good, actually. The passband is flat and only ~40MHz wide. Looks like good filter for general use. With this mixer, I should be able to re-tune it to 10368MHz easily.

Of course, I need to calibrate the "Y" axis. No idea how much attenuation came from the mixer itself. Some definitely was introduced from the measuring cables ... still work to do on my side. I will also try to use the same principle (different Local Oscillator and maybe different mixer) for 24GHz.

73 Herbert

Filters, filters and more filters

Exact, stable frequency is very important in ham radio. Especially if you intend to use digital modes, such as WSJT. I have built a GPS disciplined oscillator to generate 10MHz reference signal and used it in my 1296MHz transverter. It worked nicely ... until the moment when I connected a 40W power amplifier. Wow ... I intend to run 1500W for EME some day, so my GPS should withstand much more than 40W!

What is a solution? A filter, of course. The 23cm band uses 1296MHz while GPS uses 1575MHz. Should be easy to separate.

I have found an eBay seller named "iseeabluewhale" who sends packages signed "GPIO Labs" from Ontario, Canada. This seller offers reasonably cheap filters. One of them is a bandpass for 1575MHz (GPS frequency L1):

 

I have measured the frequency response. Looks quite good, 1296MHz suppressed nearly 60dB:

Time to test the GPSDO with this filter again. I will post the results later.

Second filter that I needed was 432MHz bandpass between my new 10GHz and 24GHz transverters and IF radio. One of them will output IF on- and below 432MHz, the other above 432MHz. Luckily, GPIO Labs make both filters, see the pictures:

Nice filters! It would be nice to find something like that for the 1296MHz frequency. There was one in their eBay listing, but the bandwidth is too narrow for the weak signal portion of the 23cm band:

 

What can we do? Obviously - get a filter elsewhere. Maybe make it ourself! For example using this design from W6PQL. I have made one of these filters (very easy to build) and here is the result:

 

Yes, this filter is quite good. Definitely cheap and easy to make. And the suppression of unwanted signals goes below 80dB!

I have recently used that filter to suppress unwanted spurious signals from ADF4351 synthesizer in the posting below. Quite a game changer there!

73 Herbert
AF4JF

MUD 2016

Microwave Update 2016 will take place in St. Louis this year. Click on this link to find more info.

73 Herbert
AF4JF

Another Synthesizer Issue

I have published my findings with a MICROSOURCE synthesizer here some time ago. That synthesizer is working fine, along with several  other ELCOM LCDFSL-1201 units in my shack. I thought that ELCOM interface is pretty transparent - until I decided to use LCDFSL-1101 programmed for 10.8GHz (10.368 + 432 = 10.8). Well, it isn't.

I have browsed Internet for a while and discovered that many others would like to know how to program that unit. There even is a new controller board for it on a web site in Australia. Hmm .. maybe later, perhaps in winter time. For now, I have found easier solution. Use ELCOM DFS-1101 instead.

The DFS-1101 does not have connector for external reference. There is an internal Xtal used (I believe 100MHz) instead. This unit uses funny frequency calculation: you have to divide the wanted frequency by 5 and add 1024 to the result. In my case (need 10.800GHz):

10 800 / 5 = 2160

2160 + 1024 =  3184 ..... 31 84 00 is the code the interface needs to generate 10.800GHz

I will keep looking for a solution compatible with my LCDFSL-1101 unit. Until found, this cheap DFS-1101 will do the job.

 DFS-1101 unit (left) with my test board with PIC (WW2R design)

Frequency ~ 10.800GHz, voltage 14.7V (before stabilizers), current 646mA.

Unit works with +6V (some ELCOMs require 8V)

My Microwave Activity

I wasn't very active since my last posting on this blog ... in fact, I wasn't active at all. Only made several dozens of QSOs on 160m during winter months. My job keeps me busy and often out of town for weeks without end.

Looks like this is about to change soon. I should be able to return to my hobby and work on all my delayed ham radio projects (along with house maintenance, of course). Here are some of them:

• 24GHz transverter
• New 10GHz station with 3ft antenna and TWT amplifier
• Beacon for 23cm

I have obtained two TWT amplifiers. One for my home QTH, another for my portable station. Pictures will be here on my blog site soon.

73 Herbert

MAD (Microwave Activity Day) on 7/6/2013

The SLAMS group participated on another Microwave Activity Day (MAD) on Saturday July 6th, 2013. I went to my usual location, YMCA parking lot in EM48sq, together with Mel K0PFX and Armand, KD0PXF:

I was set up for 10GHz (dish on the left side), 23cm and 70cm - mostly because this was a first test on few 15el. Comet antenna. It worked well and, even better, this antenna is easy to assemble/disassemble in field. I am going to replace my 12el. Cushcraft with this one and use the Cushcraft at my house for Packet Radio 9600Bd.

Detail of my 23cm gear laid out on a table:

I have experienced the same problem with my transverter - it was overheated even when taken out of the car! Direct sunshine  is able to heat the box to high enough temperature to trip the PA thermal protection. I will have to do something about that before next contest ...

73!

2013 ARRL JUNE VHF QSO PARTY

Once again did some of the SLAMS members participate on a VHF+ contest. I have set up equipment for 144/432/1296/10368GHz in my usual location at YMCA in Westport, EM48sq.

The location actually is identified by following Maidenhead grid designator (according to my GPS): 

EM48SQ58AX

It was one of the hot days, so common in St. Louis. Temperature only 85F, but direct sunshine. I was quite dehydrated in the evening. Even my 23cm transverter didn't like the sunshine and started tripping the temperature protection on me. Covering the box with newspaper fixed the problem, but it gives everybody an idea how hot the day was.

Best achievement for me today was ~200 miles QSO on 432MHz with Zack W9SZ using my 11el. portable Yagi and <5W of RF output from my FT817. I have also worked Zack on 144 and 1296MHz today, but not on 10368MHz.

my usual setup

antennas "from behind"

another view of my setup

That "eggbeater" worked fine

even on my 200 miles QSO

with W9SZ on 144MHz.

This contest always "opens the season". I will post some more pictures from future contests here as usual.

73 Herbert

AF4JF

MICROSOURCE Synthesizer Issue

I have obtained two MICROSOURCE synthesizers some time ago. Label on that device says:

       FREQ:   10.2 - 13.35 GHz

I was told by several other HAMs that this unit is practically identical to ELCOM unit and can be controlled through a device with 12F675 processor, such as described by Dave WW2R here. The only difference is supposed to be the oscillator type - ELCOM uses "DRO" while MICROSOURCE uses "YIG".

I am not a beginner with ELCOM synthesizers. In fact, I already have a 24GHz transverter based on DFS1201, so I thought that using this new MICROSOURCE unit to generate signal for 24GHz beacon would be piece of cake. Well ...

The synthesizer simply refused to cooperate. I tried to program it for various frequencies above 12GHz, but it always generated 12GHz output signal (note that my counter isn't locked to GPS yet):

I spent hours researching Internet and checking my wiring, switching synthesizers .. nothing. I even contacted Dave WW2R by email, but he didn't have "hands-on" experience with this model. After quite some time I finally remembered that Michal OK1VM published something about this synthesizer on his web site, so I have sent him an email.

OK1VM told me that he has some recent experience with this synthesizer. He also mentioned that although the label on the MICROSOURCE unit says otherwise, it ONLY responds to programmed frequencies in the 11.2 - 12.0 GHz range. So, I have modified my programming to 11.88GHz and here was the result:

OK, the synthesizer works. I can't use it for a small 24GHz beacon, but there are many other ways how to utilize these wonderful devices. 

Again, no matter what the label says, both of my MICROCOM units let me set them to a frequency in the 11.2 - 12.0 GHz range ONLY, exactly as DFS1201 from ELCOM.

So, before you decide to buy such a unit (mine came from eBay), be aware that your synthesizer might have the same limitation as mine does.

Thanks to Dave WW2R and Michal OK1VM for their help with solving this mystery!

73 Herbert

SPRINT - last microwave contest of the season

I have attended the SPRINT contest from YMCA parking lot in EM48sq on Saturday, September 29, 2012. This was my last microwave activity of the season, for I have to make series of business trips for the rest of the year.

I have achieved one significant goal today - finally, after nearly a year of trying and trying, I have worked Zack W9SZ on 10GHz CW from his location in EN50rl, over 160 miles away. This is my grid #6 from my YMCA location. Thanks for all the patience, Zack!

More details about today's SLAMS club event are available here.

My station today

Terrain profile

Hepburn chart

Weather conditions

Vapor image

(I believe that this made the difference)

73 Herbert

AF4JF