Configuring Hermes Lite 2 SDR, Quisk, Direwolf and Hamlib

Direwolf starting with hamlib support enabled

After multiple failed attempts to trigger Quisk PTT via CAT on a virtual serial port, I discovered later Direwolf versions include support for Hamlib. This itself was also not straightforward as by default, Direwolf is not compiled with Hamlib support.

Firstly, we need to ensure Hamlib development packages are installed (or alternatively, compile from source ourselves). I took the lazy option, so under Fedora:-

sudo dnf install hamlib-c++-devel

I then recompiled Direwolf to include Hamlib support:-

[snetting@rhlap direwolf]$ make clean
rm -f direwolf decode_aprs text2tt tt2text ll2utm utm2ll aclients atest log2gpx gen_packets ttcalc kissutil cm108 gen_fff tune.h fsk_fast_filter.h *.o *.a direwolf.desktop

[snetting@rhlap direwolf]$ make 

... output snipped, but watch for the following:

\t>\tThis does NOT include support for gpsd.
\t>\tThis includes support for hamlib.     <<<---- HAMLIB!
\t>\tThis does NOT include support for CM108/CM119 PTT.
[snetting@rhlap direwolf]$ sudo make install

Then, direwolf.conf is updated to configure basic settings, the only setting of specific note is the PTT:-


This matches the configuration in Quisk, Config -> Radio -> IP for Hamlib, Port for Hamlib

We then start Direwolf with debug options (-dhk) and a virtual KISS TNC port specified (-p), run kissattach plus modify kiss parameters to avoid a current bug in Direwolf (related to incorrect KISS channels being used):-

direwolf -c ./direwolf.conf -dhk -p &
sudo kissattach /dev/pts/6 dw0
sudo kissparms -c 1 -p dw0

In the lines above, /dev/pts/6 needs to be set to the pseudotty created by the Direwolf (check the output). Where dw0 is mentioned you need to substitute the name of the port defined in /etc/ax25/axports.

Standard Linux ax25 commands should then function normally:-

[snetting@rhlap ~]$ axcall dw0 m0spn
GW4PTS AX.25 Connect v1.11

<<< Data frame from KISS client application, port 0, total length = 18
  000:  c0 00 9a 60 a6 a0 9c 40 e0 9e 90 66 a6 a0 9c 61  ...`...@...f...a
  010:  3f c0                                            ?.
[0L] OH3SPN>M0SPN:(SABM cmd, p=1)

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GridTracker; a JTAlert for Linux?

As a Linux user I’ve never used or understood the advantages of JTAlert. Attempts to explore this have also failed due to JTAlert not playing well in WINE. However, I recently saw comments online suggesting GridTracker is JTAlert for Linux, followed by some heated discussion bouncing between “GridTracker lacks basic functionality” and “GridTracker offers additional functionality”. Curious, I thought I’d check it out.

The feature list of both JTAlert and GridTracker look similar. However, from what I can see, JTAlert is text only whereas GridTracker plots stations and paths visually. Both offer alerts, tracking award status, automatic logging etc.

After downloading I extracted the tar and ran the executable. It was as simple as that, at least under Fedora. My complete software stack can be seen below:-

Quisk (SDR), WSJTX and GridTracker running together.

A closer look at the GridTracker window itself shows the map, current stations, PSK-Reporter band activity, current activity (station calling/being called), general status, QSO live view controls and a number of icons to toggle various display modes.

I can’t run JTAlert to compare the two packages but I must say, first impressions of GridRunner are fantastic. The custom alerts are already proving useful, the automatic logging a huge benefit plus the extra information provided is superb. The only thing I was looking forward to which is currently not working, is the text-to-speech alerts. However this is listed as a known issue in the documentation; Hopefully a future release will make use of the Linux TTS system.

Finally, I thought I’d test the messaging functionality. I chose a call at random and Russ M0DEP was quick to respond. This could have potentially led to a QSO if it wasn’t for conditions (or more likely my antenna) being less than ideal:-

Russ M0DEP kindly responding to my test message

In summary, I can only compare the two packages on paper, and at least on paper I don’t see any significant differences in claimed functionality. However GridTracker has already proven it’s usefulness and will now be in regular use at the OH3SPN shack. I don’t know if JTAlert provides the same range of information (band activity etc) or if it can plot points visually on a map but at least for me, GridTracker fills a gap I didn’t even realise I had.

Shortly after finishing this post, Russ M0DEP and I managed to work each other on 20m FT4. I’d already configured an alert in GridTracker and this demonstrated the functionality perfectly:-

Success! GridTracker alert plus completed QSO ūüôā

Further information on GridTracker (plus downloads) can be found at:-

Further information on JTAlert (plus downloads) can be found at:-

Many thanks to Stephen N0TTL for the GridTracker package and Russ M0DEP for both responding to my message request and having the patience to work a QRP station from OH-land.

A closing comment from Russ M0DEP, regarding GridTracker:-

M√ėDEP Sat 01 Feb 2020 09:47:57 UTC
Yes I love the programme. I have been using it for a longtime now. Its very feature rich if that’s your thing but it does everything I need. I do not use JT alert since using GT but I never really used JT much anyway. So I cannot compare. However I really love the GT GUI and the big maps etc etc.. So when I have visitors to the shack, being able to show people what I do is invaluable.

I’d be interested to hear from other users of both JTAlert and GridTracker; What are your thoughts?

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70W HF Linear Amplifier Project

Whilst very happy with the performance of the Hermes SDR, I’ve been considering a matching HF linear to provide a moderate (6-9dB) increase in output power. I have ideas about operating portable using battery power; ~50W seems a nice balance between power output and current requirements.

There are ready-made chinese amplifiers available via eBay that supposedly offer ~50W out. I remember researching these some time ago and reading actual output power varied significantly with band and supply voltage. One such amplifier can be seen below:-

A pre-built Chinese HF Linear from eBay

There’s two advantages to the above device; no DIY required and (supposedly) a full set of low pass filters fitted internally.

Of course, questionable output power plus the interest in building something have led me down a path that will probably cost more than the above. However, I do still intend to use a Chinese PA; albeit in kit form. This will be mounted on a suitable heatsink and enclosed with switchable low pass filters, power meters (both DC input and RF output), SWR indicator (possibly also SWR protection) plus a low-voltage disconnect to protect batteries when portable.

The module I’ve chosen:-

The chosen Chinese 70W HF Linear (eBay)

The above module is rated at 70W. Tests from others report promising results; for reference see:-

I plan to build this in a matching enclosure to my Hermes SDR, making a convenient modular system; 5W from the Hermes or ~50W with the additional PA.

The Hermes SDR. The linear will be built into an identical case.

I have yet to consider how to implement SWR or low voltage protection. Initial attempts at low voltage protection (using a modification of my ‘over voltage proection’: haven’t proved too successful; using a Zener to switch a transistor results in a sloppy response with too many variables (variable input voltage plus the responses of both the zener and transistor as they start conducting) resulting in a ~1V window where status is uncertain.

1V to an SLA/gel cell can be the difference between empty and damaged. I plan to test using a lower voltage regulator as a reference and a comparator for the digital output; I suspect this is the best way forward. My initial thoughts (and sloppy result) can be seen below:-

The ‘sloppy’ undervolt protection
The window of uncertainty between 10.4V and 11.4V
Top graph is input, bottom graph is Ic (hence relay current)

For RF power meter I intend to use a variation of the following simple schematic:-

Updates will be posted over the next few months.

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Hermes Lite 2 SDR Transceiver

The Hermes-Lite is a low-cost direct down/up conversion software defined amateur radio HF transceiver based on a broadband modem chip and the Hermes SDR project. It is entirely open source and open hardware, including the tools used for design and fabrication files. Over 300 Hermes-Lite 2.0 units have been successfully built.

Late last year I received my Hermes Lite SDR 2 plus N2ADR filter board. However, the enclusure, fan and other accessories did not arrive in time for the xmas holiday.

Now, in early 2020 I’ve finally assembled this amazing little SDR transceiver. The enclosure required a little modification in order to comfortably fit the PCB, but this was a simple job once I had access to the correct tools (thanks, Tampere Hacklab!).

The completed Hermes SDR enclosure

I was initially a little nervous about the complexity of the setup (loopback audio devices, PA bias adjustment, SDR software, interfacing with hamlib etc) but amazingly everything worked on first attempt.

Rather than manually adjust the PA bias I used the simple automatic tool from James Ahlstrom (N2ADR) available here:
Note: Despite being built in Ubuntu, the binary ran perfectly under Fedora 30.

Setting up Quisk was similarly straightforward; I downloaded the latest version, installed dependencies (in my case under Fedora 30, fftw-devel and pulseaudio-devel), added a new radio and configured the band pass filters. A little time was then spent configuring radio control in both wsjtx and Quisk and I was quickly on the air.

Screenshot showing Quisk (background, bottom line showing Temperature, TX Power and SWR) and WSJTX (foreground, in QSO with G6NNS). Full resolution image can be found here:-
Screenshot showing only Quisk; a portion of the 30m band (zoomed), plus band, mode, waterfall etc.

First FT4/8 QSOs using this radio (~6W to an indoor 20m dipole) were:

G6NNS, JO02, 14.081998, FT4, Sent: +04 Rcvd: -11
GB8HNY, IO93, 14.075045, FT8, Sent: +03 Rcvd: -24
PD7RF, JO22, 14.075867, FT8, Sent: +09 Rcvd: -05
PF2JV, JO22, 14.076013, FT8, Sent: -15 Rcvd: -25

Many thanks to the above operators for (unbeknownst to them) assisting with the first on-air tests!

Testing other modes (SSB voice, FreeDV) and everything has also worked as expected. My only current issue is what appears to be a lack of a CW keyer in Quisk (or the Hermes firmware). My paddle only works as a straight key connected to the Hermes front panel.

Closer view of the Hermes Lite 2 SDR front panel

Future plans include a build based on the Hermes but with additional PA and integrated PSU. Watch this space!

Hermes Lite SDR details can be found at
To purchase via group buy, check availability via
Latest Quisk can be found at

A great introduction video by the designer, Steve Haynal KF7O can be found here:

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QRP FT8 Operating Tips

A few tips on making the most out of FT8, especially when operating QRP.

  1. Listen on odds and evens *before* selecting a TX frequency. Just because you can’t hear anyone on the receive cycle doesn’t mean you’re not colliding with other stations on TX. Once a clear space on the waterfall has been found, lock your TX frequency with the ‘Hold Tx Freq’ tick box. This is linked with the following step…
  2. Don’t call a station on their TX frequency; you’ll be just one of many doing so. Call on the slot you found in step 1 above. All stations are decoded on RX regardless of frequency. This also enables you to tail-end a QSO without colliding with the 73 messages.
  3. If the receiving station can’t hear you, repeat step 2 to find another free slot. Just because a slot is quiet for you does not mean it’s quiet at the RX station.
  4. When calling CQ periodically disable TX and instead listen on your TX slot; check a more powerful station isn’t clobbering you, and if so, repeat step 1.
FT8 Waterfall.
A waterfall plot showing TX on an adjacent free slot

Finally, be aware of signal reports. I’m running ~2W with a very inefficient antenna. Commonly my reports will be ~8dB down compared to the report I send. Assuming similar noise floor at both ends (typically around -24dB), I only have a small chance of working someone with a -16dB signal, dropping to near impossible at -18dB or below. However, if I *really* want that contact I’ll hunt around the band in the hope of finding a spot quiet on the receive side. Occasionally this works.

Enjoy the mode and I look forward to working you on the bands.

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OH3SPN FT8 Activity

I’m now active from Tampere, Finland using the call OH3SPN, primarily FT8 on 30/20/17m due to antenna restrictions; FT817 (typically 2.5W out), G4ZLP¬†MinoProSC interface, indoor SPX-100 antenna or short wire connected to LDG Z100 Plus.

I’m very happy to report my first contacts using this call included a scheduled contact with Mark Tanner (M0MTT) and his daughter Sally Dagger (M6LHY).

Typical coverage as shown below:-

Coverage map from
Stations hearing OH3SPN, 18.01.2019 via PSKReporter

M0SPN and OH3SPN logs are available using the links above.

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As of April 2018 I’m now located in Tampere, Finland, Locator: KP11UL.  You may see my call appearing in various logs with an OH prefix whilst I’m awaiting my official Finnish callsign.

I’m currently maintaining both (M0SPN and OH/M0SPN) callsign logs on; see ‘logbook’ link above.

Initial tests on 20m using an FT817 and a 6m loop of wire, hung around an indoor window frame (using an LDG Z100+ auto ATU) can be found below.  By pure chance I seem to be throwing all my RF towards the South West.  Hello England!

The current property isn’t well suited for proper antennas so I may be limited to CW, FT8 and PSK31 for the next few months.

Steve OH/M0SPN

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Over Voltage Protection

I recently re-homed several cheap 13.8V linear PSUs from rallies, ranging from 3 to 10A. My intention is to power smaller items of equipment; TNCs, FT817s and similar. However, after inspection it became apparent that all lacked any form over over voltage protection.
I at least expected a simple crowbar circuit!

Looking at several crowbar schematics online and considering modes of failure, I thought of another option. Instead of shorting the supply on an over-voltage condition, why not simply disable output with a voltage controlled switch? If the supply voltage exceeds a safe limit (for example 14.5V) kill the output.

The problem here is how to do this without a power transistor constantly sinking current.  In the case of a 10A supply this could require a significant heatsink; Somewhat inefficient too!

So, welcome back, my old clunky friend:  the relay.


The quick schematic above (subject to revision!) is controlled by Zener D1 (in this case a 14V Zener).  When the voltage exceeds the avalanche voltage of D1 the base of Q1 starts to climb to 0.6v, becoming forward biased and hence switching on.  This in turn activates the relay, switching the main V OUT off and instead illuminating an ERROR LED.

Both the relay and error LED are both protected from over-voltage (within reason) buy a cheap 12V  regulator.

A graph showing V IN (top) plotted against the two relay outputs can be seen below. ¬†Note the current with just the LEDs (no load) is not equal as the ‘error’ LED is held at 12V.


Click to Zoom

It is shown that the switching point is between 14.7 and 14.8V. ¬†For a supply set at 13.8V I’m happy for this to occur anywhere up to 15V.

Dependent on the equipment connected, you should however be aware that the time taken for a relay to energise may still be enough time for damage to occur.  In many cases, a power transistor or mosfet either passing current or acting as a crowbar may be the preferable option.

Also, these are just my thoughts coupled with a quick simulation in¬†Circuit Lab;¬†this is untested in practice ūüôā

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Hybrid (LSD) NiMH Batteries Compared

Sanyo/Panasonic Eneloop Cells

Receiving a set of NiCad batteries as a 10 year old (for use in a ‘Knight Rider’ RC car – how awesome was that?!) started a lifelong obsession with rechargeable cells.  My interest in batteries started even earlier than this, after being given random lengths of wire, torch bulbs and supposedly dead C cells to ‘play’ with.  Well, it kept me quiet ūüôā

Maha/Powerex Smart Charger

Some 35 years later and I’m still doing much the same, only with NiMH cells and a Maha MH-C9000 intelligent charger/analyser.

Recently, I’ve switched to so called ‘hybrid’ or Low Self Discharge (LSD) cells as whilst the capacities are lower, I find the low self discharge rate to be more beneficial in the long term.

All cells are new and run through a charge (0.5C) and discharge (500mA) cycle, the average capacity of 4 cells recorded. Capacities are expected to marginally improve over several cycles.

Edit: Some have pointed out that I should a) be testing remaining capacity after 6 or 12 months and b) my tests are not the IEC standard.  Firstly, I’m not so interested in specific rates of self discharge (these tests are available elsewhere online).  Secondly, I find the standard IEC test (0.1C charge, 0.2C discharge, from memory) entirely unrealistic for my typical workloads such as amateur radio, DSLR, etc.  My 500mA discharge rate was chosen as a reasonable average figure for my typical use.

AA Hybrid

BrandTypeRated mAhMeasured mAh
SanyoEneloop Pro (black)24002386
SanyoEneloop (white)19001858
EnergizerACCU Recharge Extreme23002075
7 Day ShopGood To Go21502220
VartaRecharge Accu26002570

AAA Hybrid

BrandTypeRated mAhMeasured mAh
SaynoEneloop (white)750726
EnergizerACCU Recharge Extreme800742

This post will be updated as further brands/types are tested.

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Chord DM01 vs Samson Q7

I’ve been very happy with my cheap dynamic mic¬†(a Chord DM01) and have received many complementary reports on my audio. ¬†However, having recently been asked to co-present a podcast I needed to confirm the mic was up to the job; ¬†high fidelity podcasts are a world away¬†from audio squashed into 2600kHz and bounced off the ionosphere.

Chord DM07 on Desk Stand

Chord DM07

Initial tests sounded a little flat and lifeless; ¬†nothing that couldn’t be solved with a little compression and EQ but this started¬†me thinking about better solutions. ¬†My previous ‘go to’ mic has always been the Shure SM58 but I was reluctant to spend the money, especially when recent reviews of other brands claimed better performance for significantly less cost.

So, meet the Samson Q7. ¬†Great reviews almost everywhere you look. ¬†Many users reporting better real world performance than the Sure SM58, some saying it’s now their preferred choice of mic and some even going as far as saying they’ve replaced all their mics with Q7s.

Samson Q7 and Chord DM01

Samson Q7 (top), Chord DM01 (bottom)

Fantastic! Just what I need, at at £25 delivered it seemed a bargain!

First impressions?  Flat, dull and lifeless with booming bass.  Suddenly, my Chord DM01 is sounding like a microphone costing many times the cost.  Perhaps I underestimated the Chord all along?

I tried several tests (both recorded and on the air) including varied positioning.  The Chord performed better in all tests, sounding significantly livelier.

For communications in poor conditions this extra clarity is of utmost importance but even for podcast use, I think the Chord wins hands down.

If you’re curious, I recorded a brief test and review; click the play button below. ¬†This was recorded directly from the mics; no pop shields, EQ or compression was used.

Play Button

Click to Play

Can you recommend a better¬†dynamic microphone? ¬†I’m open to suggestions regardless of brand or model but would prefer to avoid condensers as my shack/studio¬†environment is far from¬†quiet.

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