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.



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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.

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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

Trail Friendly Flowerpot Antenna for Six

During the recent SOTA six and ten metre challenge, the six metre flowerpot antenna worked well.  The only thing was that it was bulky with the PVC pipe choke section.

As an experiment, I made another one, but this time used RG-174 coax and wound the choke section just as a 60mm diameter coax coil held together with cable ties.

Surprisingly, it matched well between 50 and 52MHz when the coil section was 5.5 turns with an average diameter of 60mm.  The turns had to be tightly bound together, but it seems stable and can be mechanically deformed somewhat without any noticeable difference in performance.

Six metre coax antenna

Six metre coax antenna

The original flowerpot antenna weighed 255 grams.  This one weighs 80 grams and is more compact.  Its an ongoing experiment, but so far seems to work well.

The coax section with shield is 1310 mm and the section without the coax is a further 1415 mm long.  These are the same dimensions as the original RG-58 flowerpot antenna.  This time I just used hookup wire for the end section.  The feed is 5 metres long.

Choke - 5.5 turns 60mm diameter

Choke – 5.5 turns 60mm diameter

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Mt Hotham SOTA Gathering

It all started with Brian, VK3MCD organising a SOTA gathering up on Mt Hotham VK3/VE-006 at a ski lodge.

Mt. Hotham is surrounded by 10 point summits, some easy to get to and many not so easy, so we jumped at a chance to spend a couple of days there.

Sarah and I did not leave Melbourne until 4:30pm on Friday and finally arrived at 10:15pm after a 5 hour drive plus a dinner stop at Bairnsdale.    We chose the route through Bairnsdale and Omeo so as to avoid freeway congestion on the Friday afternoon.  The drive up was better than expected, although we were driving in thick fog once we rose to higher altitudes between Omeo and Mt Hotham.


The balcony antenna


Foggy start



We awoke to a stunning scene of low cloud below us and bright sun.

On Saturday morning, we joined Brian VK3MCD, Peter VK3PF and Alan VK3FABT on a 4WD trip to VK3/VE-018, Basalt Knob-VK3/VE-039 and Mt. Blue Rag.  Most summits could be activated on 144MHz FM with a hand held due to all the other activators in the vicinity.  Brian’s Landcruiser made easy work of the rough tracks past Mt. Blue Rag.  The morning was mostly foggy, limiting the views.  40m was a bit average for propagation, especially locally.  Activity on the summits was fast and furious with lots of summit to summit contacts with the other activators.  It did get a bit confusing at times though.


Sarah on Mt. Loch

In the afternoon, we hiked over to Mt. Loch, VK3/VE-005 with Adam VK3AGD.  The walk is about 7km return and it was getting quite warm.  We had fantastic views from the summit and could see Andrew, VK1AD and Adan, V1FJAW in the distance on the track.



Hotham Happy Hour


Station on Hotham

The day was topped off with a happy hour on top of Mt Hotham VK3/VE-006.


Hotham Happy Hour

Several stations were set up on HF and there were countless exchanges on 144MHz FM.  It was hard to keep track of who was on and where they were.

The weather conditions were again perfect with no wind and bright skies.

After returning to the lodge we enjoyed a terrific meal organised by  Kathy.

After a late start on Sunday, we went towards Omeo and activated VK3/VG-030. Unfortunately, we were greeted by a fallen tree at the start of the track off the Omeo Road and had to walk to the summit, which was activated solely on 144MHz FM.  We had walked a short distance down the hill on the way back, when Sarah asked me if I had my phone.  Sure, I had my phone, but no GPS, so it was a walk back to the summit where the GPS was patiently waiting.

The weekend was 54 points in total for me, but some of the others would have done a lot better than that, especially those that stayed over on Sunday.

In all, we had about 20 attend for the weekend and some stayed on an extra day.

Operators included Brian-VK3MCD, Ron-VK3AFW, Andrew-VK1AD, Andrew-VK1MBE, Adan-VK1FJAW, Peter-VK3PF, Alan-VK3FABT, Rob-VK2QR, Alan-VK3ARH, Tony-VK3CAT, Ken-VK3KIM, Compton-VK2HRX (I hope I haven’t missed anyone!)

Special thanks to Brian and Kathy for organising the weekend!


Relaxing with the view


Hotham Station



The Twins?




Hazy mountains

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Dingo Ridge VK3/VC-028

Dingo Ridge was the first SOTA summit that I activated along with Peter, VK3ZPF.  That time we took a longish route along some closed off 4WD tracks.
Peter had since found another easier track to Dingo Ridge and more recently Tony, VK3CAT had been that route.
It was nice morning, so I decided to go for a short hike for a bit of exercise and some SOTA as a bonus.
The Prince’s Freeway was taken from Narre Warren to the Garfield North exit.  The Garfield North Rd. goes north where the Pettigrew Rd. is taken to the left.  This road finishes at a farm driveway.  There is a track to the left that takes you straight to the Dingo Ridge activation zone.  The track is about 2km long and moderately steep, climbing about 225 metres in altitude.  At the start of the track there is a sign stating that that no vehicles are permitted and that it is private property.  There were a few horse riders on the track as well.


Track start


At the top

At the top, the “flowerpot” 6m antenna was attached about 4 metres up the squidpole and the 40/20/10m end fed antenna attached to the top of the pole.  The station was on air at 11:26 local.
The summit was qualified on 6m and some DX was heard but not worked.  10m was wide open to VK2 and VK5.  Paul, VK5PAS was a consistent 5×9+.

Many contacts were made on 10m until about 12:50pm local when it was time to go.elevationtrackIt would have been great to stay a bit longer, but had work to do at home.






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