Leo Bodnar GPS Reference Clock – GPSDO

The unit is named a “GPS Referenced Clock“. The outputs can be set in the range 450 Hz to 800 MHz. The frequency of the secondary output is dependent on the primary output frequency.

There is another version available with a single output.

The units do not tell the time, so it is not a clock in this sense; it produces accurate, square-wave “clock” output.

The unit arrived well-packaged along with its GPS antenna and USB lead. I like the plastic case for keeping the bits together. The unit is a neat, small package.

I installed the control software on my Win10 PC and connected the Leo Bodnar GPSDO to the PC via its USB lead. I attached the GPS antenna and placed the patch block on the outside of the Velux skylight. My unit is the version with two outputs. Firmware version: 1.17.

The unit took its power via the USB cable.

The “No GPS Signal” message went away. Actually, I later found that I could place the GPS antenna inside on a shelf and still get satellite lock, so the unit is quite sensitive. I have a fair bit of screening by way of foil-covered insulation reducing signals from outside.

On the software I enabled one output only.

Setting a frequency

I set the “Master” (primary) frequency to 106,500,000 Hz, 106.5 MHz and clicked Find. The software displayed:

4,437,500

N31: 11

N2_HS:11

N2_LS:1152

N1_HS: 8

NC1_LS: 6

NC2_LS: 6

PhShift: 0

BW: 6 (internal PLL bandwidth; 15 is optimum)

F3 Hz: 403 409

Fosc: 5112 (internal PLL parameter)

So the software found a way of setting the unit to the frequency I had chosen: 106.5 MHz.

32 mA drive strength should give 1.6 V peak-to-peak to 50 ohm.

As possible seconday frequencies, the software offered me: 106.5, 319.5 or 159.5 MHz.

Harmonics used as a frequency marker

I put a random rubber duck antenna on the output (possibly 70cm band).

144.08 MHz x 3 = 432.249 MHz

144.027 x 9 = 1296.243 MHz

257.8 x 9 = 2320.200 MHz

255.57 x 9 = 2300.130 MHz

266.69 x 9 = 2400.210 MHz

691.214 x 15 = 10.368.210 MHz

With the 19,368.210 MHz frequency, I received this on my DB6NT transverter from a dish pointing at the rubber duck. The DB6NT+K3 configuration is frequency locked to a Jupiter based GPSDO. Using the K3’s spot function gave me a dial reading of 10,368.210,003 MHz, so within a few Hz.

On the K3, the transverter off-set frequency can only be adjusted to the nearest 10 Hz, so I cannot tune it any more accurately. The LB GPSDO accuracy is probably within 1 Hz at 10 GHz; I just can’t set the K3’s internal transverter band off-set that accurately.

So I am really pleased that I can use harmonics from the LB GPSDO as frequency markers in the higher bands. I wonder whether I might be able to receive a marker in the 24 GHz band?

WordPress.com “white screen of death” on trying to Write or Edit

I hadn’t been able to add to or edit my blog for some time. I tried help chat on the WordPress site & got nowhere. I was running quite an old version of Firefox: 66.0.3. I downloaded the latest version: 89.0.2.

This seems to have fixed the problem with the WordPress editor. I was able to add an article to my blog today and to do some edits.

Perhaps somewhere on the wordpress.com site there are specifications for minimum system configurations?

19/20-June-2021 6m Trophy contest

There was sporadic E again, which was good, as intra-UK contacts were very difficult. I did hear a canadian station on SSB just before the contest. He might have been workable with 25 W, particularly on CW, but I didn’t hear any stations across the Atlantic during the contest.

My best DX was Z3A at 2,230 km.

The pattern of contects was a bit different to last year, 2020. Last year, intra-UK contacts were easier and the sporadic E favoured more distant contacts:

Knucker – decoding narrow DVB-T transmissions

I obtained a Knucker board from the BATC online shop along with a FT2232H USB Mini Module (U1 marked on the board) and a FTM-4762 Serit tuner (U2 marked on the board). With the USB Mini Module item, on the BATC shop site, there is a drop-down box for selecting the USB Mini Module version with the Knucker firmware.

I followed Mike M0MJW’s advice again for assembling the MiniTiouner2 (MT2) board.

I used the same ferrite chokes as I had used in MT2: Wurth 1.8 uH 20% Ferrite Rod Core Inductor, 5A Idc, 6mohm Rdc, WE SD from RS Components.

I pre-set the voltage regulator daughter-board, before mounting it on the mother-board.

I trimmed the back corners of the board (after the picture below was taken) so that the board fitted snugly against the back panel of the box and put a bit of polythene foam padding at the front of the board so that the board pressed firmly against the back.

Rather than use a board-mounted fuse, I opted to put a fuse-holder on the back panel. I put a rocker-switch on the front panel with the indicator LED.

Note: Unlike the MiniTiouner2, no additional resistor is needed on the USB Mini Module daughter-board. The black/blue wire connections are to the front panel LED. With DC supply connected, I checked all the voltage “Test Points” on the board & all looked OK. I added the Serit module and the USB module.

It is the lower F connector which receives the LNB output (apologies, I was incorrect before):

I inserted a few cm of wire into the lower F socket in order to receive the local broadcast ITV DVB-T as a test and connected Knucker to the Portsdown4 via a high-quality USB cable into the Raspberry Pi’s USB3 socket. The Tapton Hill (Crosspool) repeater mast is very close. I set Portsdown4 to 498 MHz, DVB-T, 8MHz wide. PD4 said “Initialising Knucker” for some seconds (so it had found the Knucker) and then “attempting to lock“, then it gave the following screen:

The Knucker/PD4 combination is not designed for wide bandwidth broadcast signals, but it is good to know that they can be used for a test when nothing else is available. The actual decode was somewhat halting in sound and video.

I have decoded 125, 250 and 500 kHz wide signals via QO-100. So long as I use my best quality USB cable and connect the USB cable directly into the Raspberry Pi then all is fine. With a slightly poorer cable or connecting via a USB hub, I got some halting in the decode stream.

On QO-100, Frank DD0CW’s test signal gave a very nice rendition of the Blue Danube and video of his back yard with no halting (250 kHz wide).

GB3KEU received via ADALM-Pluto on Langstone software (connected by ethernet)

Last year I received the GB3KEU beacon for the first time. That time the feed from the Pluto to the Portsdown4/Langstone box was via a USB cable which was a bit restrictive. Today I used an ethernet connection.

This opens up the possibility of putting the Pluto in a box by the antenna and having a pre-amp for receive and a linear amp for transmission on the 6cm band in the same box. So there would be no coax cables carrying RF to and from the antenna box, just an ethernet twisted-pair cable carrying digital packets. All the analog/RF stuff would be in the antenna box.

The video shows the Langstone software reception screen. The signal is weak, but audible, and visible in the waterfall display:

Video of reception

The Pluto is drifting, probably because it is running on its default internal crystal reference. The audio amplifier is picking up some computer noise from the Raspberry Pi 4.

The nominal frequency for GB3KEU is 5760.925 MHz, but that is not the frequency that the Pluto sees.

SAA-2N Vector Network Analyser made by Zeenko

I had been looking for a VNA which would work outdoors and which could optionally be connected to a PC with software for bench work indoors. The VNA is built in a nice metal box with N connector sockets. The label on the back says 50k-3GHz, H/W version V2_2.

It came in a nice protective case & included a calibration kit.

I loaded the VNA-QT software onto my Ubuntu Linux PC. This allowed me to upgrade the firmware on the VNA.

Updating the firmware

The VNA had version 202001117 on it when it arrived. This seemed to be a bit buggy, so I looked for the latest version. I found Unofficial Hardware Variants , “V2.74” from blackmagic 2020-10-13 firmware download worked OK. 106kB loaded.

From github nanovna-v2/NanoVNA-QT, I downloaded NanoVNA_QT_GUI-x86_64.AppImage onto my Ubuntu Linux PC. Windows versions are available. I had to alter the permissions on this to allow it to execute. Executing gave a screen with the banner: VNA View.

Holding down the left-arrow button on the VNA (the button closest to PORT1) and switching on the VNA gave me a white, blank screen, indicating serial upgrade mode.

Wtih the VNA connected to the Linux PC, VNA View then allowed the VNA to be selected in the Device menu and have the new firmware flashed.

SAA2/NanoVNA V2/V2 Plus/V2 Plus4 user group forum

I have discovered today (2-April-2021) that the original developers have a dispute with Hugen/Zeenko. So having found what I took to be officially-supplied firmware for “Unofficial Hardware Variants”, I now see there may be really no support at all. This is a complicated world!

Portsdown + Langstone both using “3D Sound” USB audio dongle

I already had Langstone outputting sound via a “3D Sound” USB dongle. I wanted Portsdown sound to come out of the same dongle.

I referred back to Dave G8GKQ’s advice on the BATC forum.

I connected the Linux PC to the Portsdown‘s RasPi4 by ethernet, booted Portsdown & ran a putty session in a terminal, chose Hostname (or IP address) as 192.168.1.51 (the address I’d specified in Portsdown), port 22 and then clicked Open.

In the putty window I logged in with:

User: pi
Password: raspberry

With the “3Dsound” dongle plugged in to the RasPi4 I checked the available devices by entering arecord -l. This produced the report as follows. Note the reference “Set“:

card1: Set [C-Media USB Headphone Set],device 0:USB Audio [USB Audio]
subdevices: 1/1
Subdevice #0: subdevice #0

I edited the file which specifies the audio output device for Portsdown:

cd ~/rpidatv/scripts
nano lmvlcff.sh

Line 57 was the then clause in a nested if statement:

if [ s? == 0]; then
AUDIO_DEVICE="hw:CARD=headphones,DEV=0"

I edited “headphones” to “Set” (for the “3D Sound” USB dongle) and saved the amended file. I left the Config setting Audio Out = RPiJack. On re-booting Langstone, I got sound through the USB dongle from LongMynd. So then both Langstone and Portsdown output sound via the “3D Sound” USBdongle.

RF power meter: HP363 Chinese board: 1 MHz to 10 GHz

I bought a power meter board over eBay. It has a plug-in display screen board which sits on top of it. It is rated up to 1mW, so needs good attenuators and/or a directional coupler. The soldered connections for the SMA connector needed re-soldering.

I cut a bit of polythene foam to support the floating edge of the display board:

I plugged the display board in:

I couldn’t find a source of ready-made extensions for the SMA buttons on the board, so I improvised by sticking a bit of plywood inside the lid and drilled holes in it for dowel pegs:

I had salvaged a button facia from an old mobile phone. I cut a piece of this for dowel covers & stuck it on with superglue:

It is a bit of a bodge, but it works! C toggles from add to subtract, CL toggles between Power Measurement and Attenuator Setting, OK alters the attenuator setting (adding or subtracting). Menu covers up a blemish on the case.