Seductive serendipity / Verleidende serendipiteit

June 1st, 2016

First EU decode of VK9WI balloon!

Receiving really weak signals on shortwave remains a challenge and is far from trivial,
especially in noisy Europe.

This year I was one of the few -and sometimes the only- northern hemisphere
station able to receive some balloons, floating above/on the southern hemisphere.

To my astonishment I decoded PS-65, aka VK9WI, this night !

2016-06-01 00:30 VK9WI 10.140257 -25 1 CD07 0.5 PA3FYM2 JO22nf 17608 76

Looking into the database this is the first (and only) European decode since its launch!

Below a map of stations who received VK9WI in the last 24 hours (click to enlarge).

The receiver used is homebrew (description here) and antenna is a 100m long ‘bent’ open Beverage.


April 11th, 2016

Junkbox 10 and 27 MHz GPSDO for Es’hail2

A priori: Click on images to enlarge in new tabs.

Es’hailSat-2 launch is scheduled for 12 October this year. Look here.
It is planned to carry a first geostationary payload for amateur use in history!

However . . . the AMSAT contribution to this payload is (kept?) vague and
it’s a mystery to me what AMSAT hardware actually will be shot into space.

Es’hail2 is a commercial (broadcast) satellite. So . . . they have plenty of
Ku –> X band transponders and almost certainly also Ka –> K band transponders.

Uplinks for Ku –> X transponders are in the 12-14 GHz range, downlinks around 10 – 12 GHz.

So, it could be well that the AMSAT 3cm allocation (10.45 – 10.50 GHz) ‘bleeds through’
a lower transponder edge. This may suggest that the only ‘additional AMSAT payload’
may be a 2.4 GHz receiver with antenna. Baseband output (let’s say 10 MHz wide)  of the
2.4 GHz receiver may be upconverted to around 12 GHz, simulating a ‘normal’ earth uplink
which is linked down around 10.5 GHz. How to deal with AGC issues is not trivial.

The 10.5 GHz downlink is divided into two portions: 250 kHz narrow band and 8 MHz
‘wide’ band for DATV use or other amateur broadband application.

Anyway . . . the scheduled 250 kHz ‘narrow band’ transponder from grounds perspective is:

1. Uplink is centered around 2400.175 MHz. Polarisation RHCP and EIRP ca. 31 dBW.
2. Downlink is centered around 10489.675 MHz. Polarisation is LV and G/T ca. 13 dB/K

Thumbs up for the people who did the lobby, VERY fine job!

My quick & dirty idea for a 10.489 GHz downconverter involves a satellite PLL LNB.
These PLL LNB’s are cheap and own reasonable noise figures (NF) around 10.5 GHz,
which is somewhat below their target band around 10.7 – 11.7 GHz.

Although HDTV requires more stability, PLL’s inside these LNB’s are not stable enough
for narrow band (e.g. SSB) operation. However, there are solutions in order to significantly
improve LO-stability in these LNB’s to comply with narrow band usage.

One of these methods involves injection locking the PLL-reference signal into
the LNB. Most LNB’s use a 27 MHz (crystal) reference. So, the trick is to ‘overrule’
the built in oscillator with a more stable 27.000000 MHz signal.

Contrast to other AMSAT satellites, Es’hail2 will not contain doppler due to its
geostationary slot. Normally you would transmit a signal on the uplink frequency and
listen to the downlink with a separate receiver in order to determine doppler offsets
because the satellite is moving.

Now the satellite hangs at a given geostationary location (26° E) so it’s merely a
giant repeater with some delay and a gigantic repeater offset. ‘Shift’ is -8089.5 MHz (!)

This means when you’ve adequate frequency precision on earth, one transceiver suffices!

Because most uplink contraptions will be build with a block upconverter (aka BUC),
locking the upconverter LO to a frequency standard is pretty straight forward.

The downlink converter, i.e. the PLL LNB, has to be locked to the same frequency standard.

My idea is to build a ‘box’ with all necessary equipment inside, i.e.:

1. 432/144 MHz –> 2400 MHz upconverter (ca. 10 – 20W ‘at the feed’)
2. 10.489 GHz –> ? MHz downconverter
3. GPS disciplined oscillators (GPSDO) for 10 and 27 MHz.
4. Power supplies, switching stuff etc.

This box has to be placed near/under the (dual band, i.e. 2.4 GHz LHCP, 10.5 GHz VP) dish feed.
(Note: to achieve RHCP you need to build a LHCP dish feed!)

10 MHz GPSDO’s have been extensively published (Google on it). The idea is to lock
the LNB 27 MHz reference oscillator to a 10 MHz GPSDO. Most LNB’s own LO’s at 9750 MHz.

This means that there is a 9750/27 = 361.1111 multiplication factor. Assuming the IF transceiver is
stable enough, to have e.g. 10 Hz frequency accuracy at 10.5 GHz, the LNB LO needs a precision
around 1E-9. This means the 27 MHz reference signal needs 1E-9 / 361 = ~ 1E-12 (!)

Whether I can reach 1E-12 precision with junkbox parts has to be found out.
The proof of the pudding is in the eating, so I scraped my junkbox and started building.

Below my initial circuit sketch is depicted.

The circuit above is a schoolbook PLL example. A GPS receiver provides a locked 10 kHz reference
to an XOR phase detector, followed by a loop filter controlling the 10 MHz TCXO phase/frequency.
TCXO output is levelled to TTL and divided by 100 (HC390) and 10 (4017) to deliver 10 kHz.

Of course two HC390′s could be used, but my junkbox revealed only one piece. The 4017 carry
output (pin12) is used to deliver a 50% duty cycle 10 kHz square wave.

Et voila . . . the loop is closed and (hopefully ; -) locked.

Next idea is to build a 27 MHz VCXO. Its output has to be levelled to TTL and subsequently
divided by 27 (= 16 + 8 + 2 + 1) to obtain 1 MHz. Division by 27 is done with a binary counter.
In the initial circuit sketch a 4024 was selected. However, I discovered my junkbox had more
4040′s than 4024′s. A 4020 or HC590 also works.

Although the resulting 1 MHz duty cycle will be (27-16)/27 = 40%, my initial approach
is to ‘stretch’ this to 50% by means of a D-flipflop which is clocked on the positive edge.

Side effect is that the 1 MHz signal is divided by 2 to deliver 500 kHz.
Therefore the 1 MHz signal point from the 10 MHz GPSDO passes through an identical D-flipflop.

Both 500 kHz signals are fed into an XOR phase detector, followed by a loop filter to provide
the necessary control voltage to discipline the 27 MHz crystal oscillator.

When 27 MHz VCXO lock yields nice results, discarding the two D-flipflops (74HC74)
adheres to a more minimalistic and junkbox approach ; -) Perhaps something to try later . . .

The PLL loop filter took quite some fiddling. The used TCXO can be slightly adjusted and its
VCO gain K (Hz/V) is relatively low. While experimenting, this meant l o o o ng locking times.
With patience I managed to get the loopfilter response and damping factor such that it seems ok.

I haven’t measured the 10 MHz signal on a spectrum analyser, so I haven’t the faintest clue on
phase noise and spurs. But.. what I certainly know, there is a spur around 10.140.000 Hz . . .
Very likely this spur is derived from the 10 kHz reference and super imposed on the 10 MHz signal.

From the left picture above it can be clearly seen that the 10 MHz TCXO is crying for discipline
after a cold start with no GPS fix. After the 10 kHz reference is locked to GPS the TCXO is disciplined.

The right picture above shows a cold start with a valid GPS almanac.

Next, build the 27 MHz oscillator and lock it to the GPSDO. More to come !


March 20th, 2016

Bulgarian yoghurt on 23cm

In 1992 I built a 23cm transverter consisting of two units:

1. UEK3 clone (we had the PCB layouts then ; -), i.e. 1152 MHz LO with 1296 –> 144 MHz RX converter
using a MGF1302 GaAs fet preamp and CF300 mixer.

2. DJ9HO (sk) ‘UHF Unterlage’ or DD9DU style 144 –> 1296 MHz TX converter (output 500 mW @23cm).

Below pictures of my homebrew units are depicted (click on images to enlarge in new tabs)

UEK3 23cm RX converter (by PA3FYM)       23cm DD9DU ‘UHF Unterlage’ TX converter (by PA3FYM)

This transverter served and worked well for some years with a Mitsubishi M57762 module, delivering ca. 17W out on 23cm.

However, when I moved to Groningen in 1997 the transverter landed in a box and remained there for almost 20 years.

Recently I was philosophizing about a long term project: building a 23cm EME station.
I held the transverter in my hands and thought . . . isn’t there something more state of the art, after ca. 25 years passed by?

Let’s face it  . . . over the past 20 years the world changed. GSM, DCS1800, UMTS and now LTE/4G is common practice.
These applications introduced new lines of RF technologies ‘around 1 GHz’, and here I’m standing with old skool gear in my hands?

In December 2014 Arie PAoEZ (sk) told me he bought a ‘Bulgarian 23cm transverter’.
When he told me I didn’t took much notice because I was more concerned about his health.

Around two months ago my friend Hans PE1CKK confessed he bought the same Bulgarian 23cm transverter and told me:
“Remco, quit the old stuff we used to build long times ago. It’s a nuisance, just buy this Bulgarian transverter and focus your
efforts and attention on other stuff.” <– period.

Google led me to the 23cm transverter from LZ5HP. Just one box with everything in it!
RF output on 23cm is around 2W. LO is generated by a PLL locked oscillatorwith several LO frequencies
and . . .  repeater TX shift (-28 or -6 MHz) !

After pleasant emails with Hristiyan LZ5HP I payed 164€ via Paypal and
received the 23cm transverter after three days by mail (with track & trace).

Below a close up picture of the transverter is depicted (click on image to enlarge in a new tab <- worthwhile! ; -)

LZ5HP ( 144 <–> 1296 MHz transverter.

The transverter is versatile and works fine. After five (5) minutes you’re QRV on 23 !

At this moment of writing the current transverter version is v2.3.
It has the possibility of injecting an external 10 MHz reference signal instead of the internal 26 MHz TCXO.
I have tested this with my 10 MHz Rubidium standard and it works flawlessly.


October 27th, 2015

Junkbox 30m WSPR receiver

WSPR (pronounced as ‘whisper’) stands for Weak Signal Propagation Report and
is invented by Nobel laureate Joe Taylor K1JT.

WSPR algorithms are able to look ca. 30 dB deep into the noise. The result is that with
very simple and low power equipment world wide communication is possible.

Having built a standalone WSPR beacon with an Arduino and AD9850, I thought
it was time to build a simple 30m WSPR receiver.

The following isn’t Nobel prize worthy nor state of the art, but can be considered as an example of how
lots of fun is realized with a minimalistic approach and simple components.

Minimalistic approach.
Google found some simple 30m receivers. However, as fas as I could ascertain the ’30m root design’
is from Onno PA2OHH using a subharmonic mixer, also known as the Polyakov or ‘Russian’ mixer.

A mixer is actually nothing more (or less) than switching a given signal, in this case the received 10 MHz signal,
at a certain rate. This rate is called the ‘local oscillator’ (LO). The (mathematical) result in an ideal world
is that the LO signal is nulled out and two side bands mirrored around the (disappeared) LO signal appear.

Although being not super ideal, the elegance of the Polyakov mixer is that switching occurs at
both the ‘positive’ and ‘negative’ peak of the LO (sine) signal, thus having two ‘switch opportunities’
during one sine period.

In practice this means the LO frequency can be halved, which is advantageous in a direct conversion receiver approach.

I happened to have two 5.0688 MHz block oscillators in my junkbox and went for a similar approach as Joachim PA1GSJ
but did not include the 10.140 MHz ‘band pass’ crystal as I didn’t found one in my junkbox.

It is stated that subharmonic mixers do not work properly with square wave forms because
there are no clear ‘switching points’ for the diodes. As I hadn’t a 5.0688 MHz ‘filter’ crystal available,
reshaping the square wave of the block oscillator was done with one RC-network.
The result is a ‘triangularish’ wave form with supposedly enough discernable thresholds for the diodes.

The receiver was build with junkbox material and the circuit diagram and prototype are depicted below
(click on images to enlarge in a new tab).

Figure 1. Circuit diagram                            Figure 2. One hour later ; -)

Circuit description.
The circuit diagram in fig. 1 is straight forward.
L1 provides some selectivity and a ‘Josti Kit’ microphone amplifier boosts the received
10 MHz signal, which it is fed to the Polyakov mixer, consisting of two anti parallel diodes.

I did not use a potmeter to ‘equalize’ the diodes. The output of the mixer is fed through a RC filter (2k15/2n7),
selecting the audio spectrum (f-3dB = 1/(2πRC). This is fed into another Josti Kit amplifier with
another RC low pass filter. The resulting audio level is more than enough for standard (internal) PC soundcards.

The exact LO frequency was determined with a GPS locked signal generator by determining
the zero beat frequency. With the oscillator block used this appeared to be 10.135.538 Hz.
Apparently this block oscillates somewhat lower than 5.0688 MHz, namely around 5.0678 MHz.

Inserting -47 dBm 10.140200 MHz into the receiver yielded, after tuning the input circuit (60 pF trimmer)
and 4k7 LO potmeter, a nice sine wave with ca. 1.6 Vpp on my oscilloscope, see below (click to enlarge).

Update: After my UK trip (read below) and while fiddling and trying to improve the receiver,
i.e. maximizing the audio level relative to the injected 10.140200 MHz (Pref = -47 dBm),
I discovered that the waveform of the LO signal is more important than I initially thought.

Increasing the 100 pF capacitor to 220 pF in the LO RC-network resulted in a ‘cleaner’ LO waveform
but with lower amplitude. This is not surprising as f-3dB of the RC-network is now around 2.2 MHz, thus
‘damping’ the 5 MHz signal significantly. An alternative could be two RC-networks, but I was too lazy for that ; -)

Replacing the mixer diodes (initially 1N4148, BAW62 etc etc) with low barrier diodes like BAT86′s resulted in a
‘smoother’ adjustment of the LO level with a sharper maximum in the audio response.
The audio level increased around 10% to ca. 1.8 Vpp.

I tried a common base amplifier behind the mixer as it is said that a Polyakov mixer needs low Z termination.
Besides I had less less audio (of course), I didn’t experience less receiver noise.
On top of this, the minimum discernable signal (MDS) was higher compared to the original setup.

I also tried KE3IJ’s ‘double’ Polyakov mixer. It indeed results in more audio, but during that
evening it was an ‘AM hallelujah’ with the BBC world service competing with other broadcasters who
would be stronger than the desired WSPR signals.

So, I went back to two antiparallel diodes trusting they are ‘balanced’ enough.

Receiving WSPR signals.
By default WSPR software looks into the 1400 – 1600 Hz part of the audio spectrum.
The user has to tune his SSB receiver to the ‘USB dial frequency’, which is 1500 Hz
lower than the actual transmitted 4-MFSK WSPR signal. On 30m 10.140.100 – 10.140.300 Hz
is allocated for WSPR. Thus the ‘USB dial frequency’ normally is 10.140.2 – 1.5 = 10.1387 MHz.

However, this receiver has no ‘USB dial’, it uses a single frequency LO, which happens to be
lower than 10.1387 MHz, in my case 10.135538 MHz. This ‘USB dial’ difference is 3162 Hz.

In WSPR 2.xx the I/Q-option (for SDRs) can be (mis)used to compensate for this frequency difference.
Just fill in 3162 as ‘Fiq’ in the appropriate settings window.

How does it work?
Summarizing: the receiver works flabbergastingly well!
Especially considering its simplicity and the fact you receive both sidebands.
I experienced no AM ‘bleed through’ and it takes around 5 minutes before the LO is stable.

During a short holiday near Rye (England, JO00JW) I tested this receiver using only 5m of thin wire
as antenna, fed through a window of our camper. The received unique 30m spots can be viewed here.
Perhaps you are among them? It should be noted that the RX environment was very quiet.
MUCH better than here in Holland with lots of PLC equipment and LED lights polluting the radio spectrum!

This experiment also demonstrates that a clean radio spectrum is of significant importance
and not specifically receiver/conversion gain. As long as you can hear antenna noise it’s OK.
If you hear more than antenna noise, like computers, plasma screens, LED lights, PLC etc. more expensive
(and better?) receivers have no added value.

I was pleasantly surprised repeatedly receiving my own 30m WSPR signals from Holland!
Output there is around 150 mW and the antenna is a 3m long curtain rail (with curtains ; -)

During the evening and night lots of US stations were logged with good signals, despite the small RX antenna.
The fact that I was located near the sea certainly may have helped.

Below some pictures of the setup in and around the camper (click to enlarge in new tabs).



July 5th, 2014

El Cheapo AFSK (e.g. RTTY) USB interface (for FT-8×7)

Being licensed for >27 years, my first steps into RTTY were during my 7QNL DXpedition in Malawi in May/June 2014.
According to ClubLog ‘digital’ modes from Malawi were (relatively) scarce, so I was obliged to give it a try.

It appeared that the built in sound card of my laptop did not work properly (with Windows 7?).
Fortunately I took a cheap USB sound dongle with me, which worked. The results were (imho) flabbergastingly good.
Signals with (very) low SNRs decoded properly.

I used the 300 Hz CW-filter in ‘DIG’ (i.e. ‘LSB’) mode on my FT-857, resulting in a ca. 1450 Hz mark pitch.
(It took me one day to discover that my dial frequency had to be tuned 1450 Hz up, anyway ….
I was on the right side of the pile up ;  -)

At home I received a few requests from my QSL manager to verify some QSOs people claimed,
as they could not find themselves in the online (Club)log.

Fortunately I recorded received audio of the whole operation for pile up research purposes.

Soon I discovered the disadvantage of not recording the audio of my own transmissions.

Before the DXpedition I thought about an ‘audio fork’, but limited time forced me towards other priorities.
Fortunately some audio of my CW transmissions ‘leaked’ into Audacity. While listening to my phone
transmissions it remained silent. This was also the case for my RTTY transmissions.

During such DXpeditions there are always some cases of doubt, due to pile up magnitudes, pile up spreads,
erroneous databases, my own typing errors, false copied calls, QRM, LIDs, etc.

There was a specific ‘RTTY case’ where I could not distinguish if I worked ‘station A’ or ‘station B’ as they
simultaneously showed up in my recorded audio (and were ‘almost simultaneously’ decoded by mmTTY
but with a slight offset in pitches).
Moreover.. the two stations had the same prefix and shared the first letter of their suffixes (iirc).

I logged ‘station A’ (which came back with CFM) but ‘station B’ claimed the QSO. Of course it was possible I made a typing error?
After intensive post processing/filtering of the recorded audio I still was not able to distinguish between ‘station A’ or ‘station B’.

The result was that ‘station A’ remained in the log and I had to disappoint ‘station B’.
If I had recorded my transmitted RTTY-AFSK, for 100% sure I was able to distinguish between station A and B (afterwards).

The aforementioned experience brought me to instant measures.

The 7QNL RTTY interface consisted of a bare USB sound dongle (U$ 0.99 incl. shipping on Ebay ; -) interfaced with
two 3.5mm stereo jacks into the dongle, and with a mini-DIN into my FT-857.

As the price of two 3.5mm jacks exceeds the price the USB sound dongle I now directly soldered the audio cable in/at the dongle.

RX- and TX-audio is levelled with two series resistors (12k7 each, your mileage may vary) and
in- and outputs were connected through a ~47k resistor so that transmitted audio runs into the recording port during TX.

Needless to say, this works for audio generated by an external device (such as a computer/laptop).
Theoretically it should work for ‘phone’ too, when e.g. the computer is used for sound processing purposes.
I have not figured this out (in N1MM) but perhaps somebody else may give this a try?

Next … is connecting the TX-mic to the interface (with a 3.5mm jack), and mute it (with a FET) while receiving.

Note: the contrapsion is used in mono (one sound channel, see solder drop on the green audio output (i.e. TX audio) connector).
Note2: Ground (GND) of the audio cable is connected to the metal casing of the USB connector.

Here and here two RTTY QSO’s. Replay them with e.g. mmTTY or fldigi.

Below pictures of the resulting interface (click on the images to enlarge in a new window).

May 14th, 2014

Dutch CQWW 160m record Single Op

One picture says it all (click on image to enlarge in a new tab)

April 4th, 2014

Remote Beverage antenna switch for 7QNL

In the previous post I elaborated on the design of Beverage transformers.

When using several Beverages ‘out in the field’, sometimes several hundreds of meters
away, they have to be switched inside the shack.

A popular method is to use LED bar drivers (i.e. an array of comparators) in ‘single dot mode’.
The Bavarian Contest Club (BCC) published a design in CQ Contest in 1997 using the LM3914.

Although this design is very straight forward and built by many, imho it lacks one of the
most important features which is important ‘out in the field’: powering the switch box from the shack
with a phantom power supply.

I changed the design so that the switch box is powered and switched inside the shack through the RX-coax.

A W7IUV-preamp is included to compensate likely cable losses, as I will use thin (light weight) RX-coax in 7Q.

The circuit diagram is depicted below, your mileage may (of course) vary (click to enlarge in a new tab):

The idea is to use the range 12 – 24V to switch the Bevs, as I will have 50V in my PA.
Proper voltages to select specific Beverages are adjusted with the potmeters (1 – 2k each),
also to compensate possible voltage drops due to RX-coax lengths.

Below a picture of my Bev switch box (click on image to enlarge in a new tab).
Yes.. I use RCA connectors, it’s light weight .. and only <10 MHz for 1.5 cm ; -)
Note: in this picture I erroneously soldered the zener to the RX-coax.
It has to be connected to the other end of the choke of course.

March 25th, 2014

Beverage transformers for 7QNL

To fight very likely QRN in Africa for 80, 40 and 30m (open) Beverages are envisaged.
Targeted length is 2λ @80m. I plan to roll out four (open) Beverages to obtain 8 ‘directions’.

A Beverage antenna is actually a transmission line above ground. Its impedance
depends on the wire diameter and wire height above ground.

With heights around 1 – 2m and wire diameters of 1 – 2mm the impedance amounts ~500Ω.
When using 50Ω feedline the transformation ratio has to be 10, but 9 is also ok.
It’s not that critical. For 75Ω feedline transformation ratio is around 6.7.

What is more critical is that the received EMF is not dissipated in the transformer itself!

A general rule of thumb is that the reactance of the windings has to be 5x the connected
impedance. I always use 10x, thus XlBev = ~5000Ω, XlRX = ~500Ω for the lowest
frequency, i.e. 3.5 MHz.

I had some binocular cores lying around, with a measured Al = ~0.8 μH.
Stacking three of these cores results in an Al of ~2.4 μH. Rumours tell that stacking
cores improves S/N as relatively ‘more’ copper is ‘shielded’ inside the (binocular) cores.

Since Xl = ωL = 2πfL -> L = Xl/2πf = 5000/(2π*3.5E6) = 227 μH

Further, μH = Al*N² -> N = √227/2.4 = 9.7  ->  9 turns will do for the
secondary (Bev) side, 3 turns for the primary (RX) side.

For 75Ω feedlines 10 turns secondary (Bev side) and 4 turns primary (RX side) suffices.

I used this transformer in conjunction with a 100m long West Beverage during the 2014
CQ160 CW contest, and it delivered me quite a few Caribbean stations/multipliers, which
were barely/not audible on my reversible NW/SE and NE/SW 200m long Bevs.

However, my ‘biggest discovery’ was during the PACC 2014 contest where this
‘West Beverage’ was left open at the far end. It received amazingly well on 40m, and
outperformed the TX-deltaloop (of course) and ’160/80m’ reversible Beverages
in more than a few cases. During the contest it became my default 40m RX-antenna.
Nice contact was with ZL1BVB on 40m. Listen here.

Pictures of the transformers are depicted below (click on images to enlarge in a new tab).

The ‘West’ Beverage (feed point)  itself is shown below (click on images to enlarge in a new tab).


March 16th, 2014

CW ‘Plan B’ (CAT) for 7QNL

For my planned DXpedition to Malawi (7QNL, May/June 2014) I made an Artisan (Win)Keyer
to be used in conjunction with N1MM-logger. This contrapsion works very well (at home/on the bench).

However, when abroad, what happens if the Arduino ‘resets’/stops/<fill in another issue> ?

Of course the Arduino IDE is present on my laptops, and issues may be ‘programmed away
on the fly’.

But…  what if the hardware (e.g. on the Arduino board itself) malfunctions?

OK, take/bring another Arduino (of course). But what if this one fails too (for whatever (same) reason)?

A priori, ‘Plan B’ is mandatory. Actually, ‘plan B’ nowadays equals ‘plan A’ in Madagascar (5R8NL) 2007:
Use the same (serial) port for both CAT (‘frequency administration’) and (CW) keying the transceiver,
in conjunction with a separate (hardware Boolean OR’ed) keyer (I have envisaged)

In 2007 (5R) a default laptop owned a ‘decent’ RS232 interface, and I designed a RS232-compatible
CAT + CW interface (using two transistors as levellers and inverters) for my rig. It performed well.

Nowadays USB rules.

A few months ago I ordered some ‘FT232RL’ USB-interfaces (from Ebay) to program Arduino Pico’s.
The FT232RL chipset is interfaced to my rig in an utterly simple manner: just connect the wires.
No MAX232′s, no inverters, no levellers, no optocouplers, no PCB designs, etc..

Repeat, connect the proper (RX/TX/DTR) wires …  (provided your rig has TTL-inputs/-outputs).

For whatever reason I cannot not get ‘CTS’ (= ‘PTT’) working (perhaps one of the 3.3 / 5V pads have to
be shortened on the USB-FT232RL interface board?) and DTR keys the rig, and when I send the software
‘PTT command’ in N1MM-logger to my rig everything works well, also sequencing (the amplifier) <– most important!

DTR of the FT232RL chip is configured as ‘CW’ in N1MM-logger, and is ‘interfaced’ through a diode (BAT86).

That’s all (for ‘Plan B’) from 7QNL/ PA3FYM

Below a picture of ‘Plan B’ (no…, no casing –> casing = weight. Cable tie is  … handy ; -)
(click on image to enlarge in a new tab)

November 29th, 2013

CQWW CW 160m 2013

During 23/24 November I participated in the CQWW CW contest on 160m.

Look here for a report.