New SOTA Rig

The new Elecraft KX2 arrived last week.  So far it looks like just the thing for SOTA activations.  A battery pack was not ordered for it, so one was constructed from 3 x 18650 2500mAh cells with a protective polyfuse.  A 3 cell protection module is on order from Ebay to complete the battery pack.

An action camera case from Target ($6) is just the right size to house the radio, mic and a few small bits and pieces.

Looking forward to taking it out to the mountains.  Its quite a bit lighter than the FT-817 at 380 grams without batteries.  The display is big and easy to read compared to the squinty 817 screen.  The radio case has a few gaps here and there around connectors and joins, so it will need to be protected from the elements carefully.


So far, the radio performs nicely, the controls are well laid out and fairly intuitive.

The microphone for KX2 is pretty expensive at nearly $100 Aus.  Mine had a something rattling in it so I opened it up to have a look.  The rattling turned out to be a blob of solder.  While apart, I noticed that the braid wire from the cable to the internal connector was very tight and might break away if the curly cord is tugged.   There are some reasonable gaps between the PTT pressel and the shell sides, and it wobbles sideways a bit.  The mic. lets the radio down a bit in my opinion.

As its hard to avoid things getting wet with SOTA, so I wired up another smaller microphone.  This mic is well sealed with a gasket between the shell halves and the PTT switch completely sealed from moisture ingress.  The PTT switch strikes a rubber membrane with the switch is on the other side.  Being a smaller mic., it will pack better as well.    The schematic from this page was followed, although my mic. had a 2k resistor and 0.33 uF cap in parallel.   The level from this mic is much higher than the original, so a 10k resistor was placed in parallel on the cord side of the mic wiring.

20160911_101618 20160911_101823






The audio from the small mic seems OK, although I did add a piece of fabric behind the mic aperture behind the case to reduce popping.

The battery pack was built with 3 x 18650 2500mAh cells.  In this case tagged 18650 cells were used.   I have had good service from Samsung 18650 cells from Ebay.  There are many dodgy cells out there though.

The 3 cell protection pcb for the cells was obtained from Ebay for $4.00 delivered.  The pcb limits the charge and discharge current and voltage to safe levels for the cells.  After the cells were connected in series, double sided rubber tape was put over the exposed cell ends.  The protection pcb was stuck to one end of the pack to the rubber tape and wired up.  Silicone wire connects the power from the pcb to the DC connector.  The silicone wire is very flexible and wont melt.  Some Nitto tape holds the cells together until the heatshrink will cover the pack.  In the mean time the pack is going to get some charge and discharge cycles with the cell voltage monitored to make sure the cells stay in balance.

Note that if you make one yourself, you are doing so at your own risk.  Utmost care has to be taken to ensure no possibilities of a short circuit can occur in the wiring, during assembly and in the completed pack.  A short circuit inside the radio could cause extreme damage to the radio, not to mention a fire risk.  Photos below show the pack before heat shrink applied.







Just to check that the protection PCB was working, I put a dead short on the output and as expected, nothing much happened.  For another test, a potentiometer was put between the battery negative and the junction of the second and third cells.  The slider of the potentiometer was connected to the PCB input for the junction of first and second cells.  This allows a wide voltage simulation of the input to the PCB for testing how it behaves when a cell goes high (above 4.2V) or low (below 3V).

With the pack charging, the pot was slowly rotated from 4.0V to 4.3V while watching the meter on the slider.  As expected, as soon as the voltage went higher than 4.2V, the charging terminated.  Also, when then voltage went below 3V, the charging terminated.

At least I know if the cells go out of balance as the pack will not charge.  The charger used with the pack is a Hyperion RC charger.

Posted in radio communications, SOTA | Tagged , | 18 Comments

Castle Hill VK4/NH-136 Last Minute Activation 1 Point

Castle Hill is a small hill close to the Townsville city centre in North Queensland.  It was about 5:30pm when the opportunity presented itself for a quick activation.  I had the FT-817, an end fed for 40/20/10m and the RHM8B telescopic loaded vertical.  As there wasn’t much time before sunset, we parked the car at the bottom of the short stepped path to the top, walked up the steps and set up the FT-817 with the RHM8B on 20m against the railing.

Surprisingly, there were some reasonable signals coming in from VK3, so answered a general CQ and made the first contact.  Shortly afterwards after spotting, I worked Peter, VK3PF and Tony, VK3CAT.  Both stations had reasonable signals, well clear of the low noise level.  Not bad considering the antenna and the 2000 or so km distance.

After working another non-SOTA station, the summit was qualified for 1 point and we started to notice that the mozzies had arrived.

A few photos were taken of the sunset before we left.

Operating from the lookout

Operating from the lookout

Posted in radio communications, SOTA | 2 Comments

Mt Fuji JA-SO/001

Our plan was to set off from the 5th station car park at (2300 metres) around 2pm and hike the Yoshida Trail to the 8th station hut (3400m) before dark.  We would then sleep in the hut until 2am and then set off for the summit (3776m) to catch the sunrise at 4:30am.  Our group consisted of wife Sarah, daughter Meagan and her boyfriend Koyu.  My Japan callsign allocated was JP3PBQ.

I had a backpack with 3 litres of water, some clothes, lunches, dinner, breakfast, torches and of course, SOTA radio equipment.  The SOTA gear consisted of an FT817, Lipo batteries, 20/15/10m End Fed Half Wave antenna, log book, hand held and usual SOTA bits and pieces.  I didn’t really want to carry all that stuff, as the MTRV2 would have been much lighter, but it was not approved by the Japan radio authorities.  Koyu had more stuff than I did, not sure what his pack weighed, but it must have been heavy.20160702_165524

The car park was very busy and we had to queue for cars to leave the car park to provide spaces for us to enter.  The delays meant that we finally departed the car park for the hike at 3pm, a bit later than planned.  The temperature was in the high 20s at 5th station.IMG_1203

20160702_171832Its a pretty demanding hike and not made any easier on this day by the strong winds that was whipping up gravel and dust and blasting us with it.  We had a late lunch at 6th station and admired the views.  After lunch it was a long slog to 8th station with many rests in between.  You could feel the thinning air at 7th station making the going a bit slower.IMG_1199

We finally arrived at 8th Station hut at 8:30pm in the dark where we had some dinner and were shown the 90cm or so width allocated to us to sleep in.  It was very “cosy” and I don’t think any of us were able to sleep.
At 2am the lights came on and we all had some breakfast and continued the slog to the summit.  As we left the hut, the wind speed was 28m/s or 100km/hr at the summit.  This combined with -1 degrees was a chill factor of -20 degrees.  On the way up you could hear bullets of wind coming and hikers would crouch down and hang on to rocks.  A few were blown over.  It was an amazing sight to look back down and see the snaking line of hikers with head torches in the dark.

We arrived at the summit at about 3:45am to a howling gale and freezing temperatures. There is a small building with steel plate walls, which provided a little shelter while we waited for the sunrise.   The clouds eventually parted and we were treated to a stunning view of the sun and scenery below.  Sarah took some great photos.IMG_1294


At about 6:30 local time, I ventured in a clockwise direction from the top of the Yoshida trail to get to the activation zone.  This part was very exposed and care had to be taken when wind gusts came through.  I found a spot against a stone wall and tried the 2m hand held.  It was not possible to spot on SOTAwatch as no cell phone coverage for some reason. Erecting the squid pole was out of the question due to the winds.    After about 30 minutes of calling, I decided it was becoming unsafe with the wind so aborted and went back to meet the others.

IMG_1333The trip back was uneventful although the winds were still strong and we were regularly pelted with gravel and dust.   We arrived back at fifth station about 1pm.

So, not a successful radio activation, but as they say, its all about the journey!



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HF1 QRP Transceiver Project

(This project is on hold indefinitely)

This project is based around the recent HF1 QRP transceiver by Ashhar Farhan, VU2ESE. The transceiver is an interesting SSB design with wide tuning range from 0-30MHz and should cover several amateur bands.  The schematic for the transceiver can be found on the Minima mail list in this post with a PDF attachment.
After a front end 0-30MHz filter, the  transceiver uses a 45 MHz first IF and a 10 MHz second IF.  The famous bi directional amplifiers are used in the bi directional SSB sections of the radio.
The first cut will be built as modules to test it out in sections.  If successful, a much smaller version will be made for SOTA use.

The mixers will be swapped with Mini Circuits SBL-1s as I have a few in the junk box.
The main LO and second LO will use an Si5351a oscillator so the second 55MHz oscillator unit will not be required.

The Si5351a, controller and display will be taken from the earlier QRP 40m rig.

First part is to build up the bi-directional amplifiers as modules.  The boards are SMD and designed on Eagle.  They came out fairly well, although the laminator sort of jammed during the toner transfer and the board had to be coaxed through.



The boards were sprayed with lacquer before reflowing the components.  This turned out to be a slight mistake as the flux spread out with the melted lacquer under heat. Anyway, they are fine electrically, just had to be brushed up a bit.

The controller / oscillator board is finished now.  The Si5351 has three clock oscillator outputs.  CLK1 is planned to be used as the main VFO from 45-73 MHz.  CLK2 is planned to be used for the second mixer at 55 MHz, although there is some conjecture as to whether this will provide acceptable performance due to clock output crosstalk.  CLK3 is planned to be used for the BFO at 10 MHz.  The controller will switch it between upper and lower sideband.  If the crosstalk becomes a problem, the 55 MHz output will be replaced by a separate crystal oscillator.  The next job is to check the clock output crosstalk to see if it will be a problem.


The controller / clock board is single sided with a top ground plane and much the same as used for the 40m QRP rig.  An 8 pin header is for connection to the LCD display.

The cross talk between the 1st oscillator and 2nd oscillator was tested by programming CLK0 with 52 MHz (45+7, simulating a 7MHz receive) and programming CLK2 with the 55 MHz second mixer frequency.  CLK2 was terminated with 50 Ohms for the test.  The results weren’t as bad as I thought they would be.   As can be seen below, the 55MHz cross talk is down 59.5dB.  Of more concern is a spurious at about 62.5 MHz which is just over 50dB down.

Si5351-52-55Some more tests need to be done as this was just a quick look.

For the moment though, I will use the 55 MHz CLK2 output for the second mixer.  Also need to look at the 10 MHz output from CLK1.

Out of interest, the 52 MHz output was moved to CLK1 with the 55MHz still on CLK2.  The cross talk increased considerably to -45dB.  So  1st oscillator will stay on CLK0.

The bidirectional amps work fine with a voltage gain of about 12 or 21.5dB @ 5MHz.


Progress has been a bit slow due to work and other things.  Have been working on a main RF PCB that will accept the bidirectional amps and mixers.  Things aren’t as modular as originally planned for experimentation, although the bidirectional amp boards are socketed, so it will be easy to tap into the input and outputs.

The power amplifier and digital boards are separate.  So far the main RF board is 80 x 103 mm, and everything looks like it will fit in.  This is the layout so far, not much will happen in the next few weeks due to some travel.



Posted in Projects, radio communications, SOTA | Tagged , , , | 9 Comments

TR-PP-11B Hand Held Military Radio

The TR-PP-11B is a French military hand held radio designed in the early ’60s.  I came across one at the MDRC Hamfest this month and couldn’t resist it.  The radio is also known as an ER-62B and a TRC-766.  It’s fully transistorised, although of course, they are early transistors.  It is very nicely constructed, the whole radio block comes out of the case quite easily as it is held into the case with the channel selector shaft and one screw.

The radio covers from 47 to 57 MHz FM with a power out of between 500-800 mW.


TR-PP-11B Transceiver

Radio Module Side 2

Radio Module Side 2

Radio Module Side 1

Radio Module Side 1

The radio block comes apart in two pieces, each radio subsystem is in a module and most of them unplug for ease of servicing.   The channel selector is a mechanical wonder.  Changing a channel turns a turret loaded with 6 crystals.  One crystal is used per channel.  The channel selector also tunes a 6 gang variable capacitor and a permeably tuned antenna loading coil.  The mechanical force to do this comes from the way a channel is changed, the knob must be lifted out, turned and released.  The retracting of the knob aided by a strong spring then pushes on a set screw per channel which rotates the tuning capacitor.

When I powered up the radio, I found that the receiver was not working and the transmitter was drifting about 500kHz low on each of the six channels.  This was sort of expected for the price I paid.

There were some well written articles on the web about the radio, including an alignment guide, although a schematic could not be found.  I contacted the author of alignment guide and he graciously sent me a copy of the schematic from the manual.

Armed with a schematic and aided by the modular construction, two problems were found. The 11.5 MHz IF module was not working.  This was verified by taking it out and powering it up separately and feeding it with an 11.5 MHz signal.

IF module

IF module

Unfortunately, this module has a soldered shield around it which had to be removed.  Powering it up again without the shield revealed that one of the four transistor stages was not functioning.  The transistors are PNP and the modules are negative earth, so things look upside down.  The cause of the fault was a dead AFY47 transistor.

Sporting a new 2N3906

Stage sporting a new 2N3906

The cuplprit

The culprit

The_transistor must have died of old age as it is well isolated from the outside world.  This transistor was replaced with a 2N3906 (as there were a few in the junk box).  When re-assembled, the receiver sprung to life, although the demod was slightly distorted.

This leads to the other problem.  The transmitter and receiver share a common crystal discriminator.  On receive, the discriminator demodulates the FM.  On transmit, the discriminator is used to stabilise a Voltage Controlled Oscillator running on 11.5 MHz.  This VCO is where the modulation is applied.  The output of the VCO feeds the discriminator and an error voltage steers the VCO to 11.5 MHz.  The VCO is then mixed with the single channel crystal oscillator to produce the transmit frequency.

The crystal discriminator is 35 kHz high for some reason.  This means that the VCO is locking high and the TX frequency high.  On receive, the discriminator is slightly off the IF frequency and causing distortion.

The discriminator is a sealed module unfortunately!  The module was removed and then the can was carefully separated by repeated scoring of the solder sealing on the underside of the unit.  After a while, the bulk of the solder was removed and the can prized off.  Everything looked pristine inside the module.



Just to make sure, the discriminator was swept again in 1kHz increments using a generator and DSO to double check that it was still off frequency.  This was confirmed.
After checking all the components for physical damage, the trimmer capacitor was retuned for the correct frequency at almost full mesh.
Maybe the crystal had aged ?  I didn’t check the component values though.

The diodes were replaced with AA143 germanium diodes just in case they were faulty.  It didn’t change the frequency though.

The discriminator lid was then tacked on with solder incase it had to be removed again and the radio re-assembled.
Its working fine now although power output is about 400mW on all channels, it probably needs a full alignment now.

Posted in Projects, radio communications | Tagged , , | 3 Comments

Light weight SOTA Stations

Here are two lightweight SOTA stations recently put together.  The SSB station has been used, although the CW one is still waiting for the right opportunity!  (running out of excuses here).

SSB 40m Station @ 900 grams

SSB 40m Station @ 900 grams

The SSB station uses the home brew 40m transceiver, 3 band End Fed Half Wave antenna and a 3 cell 2200mAh LiPo pack.

It weighs 900 grams including the carry case.  A few more grams could be trimmed off by using Kevlar antenna wire and maybe lighter cables.  The 4.5 metre squid pole is carbon fibre and weighs an extra 200 grams.

Lightweight CW Station @ 600 grams

Lightweight CW Station @ 600 grams

The CW station consists of the KD1JV MTRV2 CW transceiver, 3 band End Fed , Palm /Mini-Paddle, End Fed Half Wave antenna and a 2 cell 1000mAh LiPo pack.  

All up including the carry case, some instructions and a dummy load, it weighs 600 grams.  The same 200 gram squid pole can be used.

The carry cases were obtained from Target and are intended for “action cameras”.

Posted in Hiking, Projects, SOTA | 2 Comments

Mt. Howitt VK3/VT-001

With Autumn weather now set in and some sunny days predicted for the ANZAC day long weekend, it was hard to resist a trip to the Alpine Park.  This was my last opportunity to visit the park before winter.  The plan was to drive up on the Saturday around noon and activate Bryce’s Plain (VK3/VT-004) and then leave early for Mt Howitt (VK3/VT-001) the next morning.  Both are 10 point summits.

Bryce’s Plain is an easy activation although there is a lot of dirt road driving to get there. The summit itself is only a few hundred metres from the Howitt Road.

After leaving home at 11:30am, I arrived at Bryce’s Plain at 3:30pm, a bit earlier than expected.  The trip was via Traralgon and Licola.  The bitumen road ends on the Tamboritha Road at the Wellington River and this section of dirt road until Tamboritha Saddle is very corrugated on the bends.  After the steep climb to Tamboritha Saddle, the road is in overall better condition.

Once at Bryce’s Plain, the car was driven about half way up the road to the summit and parked just in the activation zone.  The gear was then taken a bit further up and a dipole strung up on the squid pole.  The home brew amplifier powered from a 4200mAh LiFe battery was set up with the FT-817.

The summit was quickly qualified on 40m with 3 summit to summits, Paul VK3HN on Pyramid Hill, Gerard VK2IO on Canoelands and Peter VK3PF on MT. Hoddle.   Of note was John, ZL1BYZ on 40m as well.

A switch was made to 20m and the band was open to Europe.  I could hear many stations calling and some it seems were blind calling as they did not hear me reply.  This made it difficult to copy callsigns.  13 DX contacts were logged, when I suddenly realised I was sitting in a polo shirt and light pants, the sun had set and my fingers were numb.  The tent was not up, so I had to leave the radio, find some warmer clothes, gloves and hat and then erect the tent.  The thermometer on the pack was showing 3 degrees.Bryces-Log

Camp spot

Camp spot


Icy tent

The next morning, there was ice over the tent and a thick frost.  The thermometer read -1 degrees.  This made it rather difficult to pack up the tent quickly. The Mt. Howitt car park is about half an hour further up the Howitt Rd.

I started the hike to Mt. Howitt at a later than planned 9:30 am from the car park. The hike distance is 7km each way via Macalister Springs. The walk was uneventful and arrived on the summit at 11:20 am.  The squid pole was attached to a boulder with bungy cords to support the good old end fed loaded half wave on 40.  Summit to summits were Peter VK3PF on Mt Tassie and Hugh VK5NHG on Tothill Range.


Crosscut Saw





Quite a few contacts were made on 40m and later 20m managed ZL and VK6.


Panorama shot from the summit.


Travel times from Narre Warren North excluding stops were:
2:30 to Licola via Traralgon
3:20 to Lost Plain (Near Arbuckle Junction)
4:00 to Bryce’s Plain
4:30 to Howitt Plains car park


Hike elevation distance plot



Posted in Hiking, SOTA | 4 Comments