20 metre SSB Compact Transceiver

This one follows the design of the DK7IH Cigarette Packet Micro Transceiver.  The changes made to the original design are:
– Plug in front end, transmit driver and PA low pass filters
– FET power amplifier (IRF510) rather than bipolar
– Toroid filters for front end, transmit driver and PA low pass filter
– Discrete crystal SSB filter
– Nokia type LCD display

The construction is mostly SMD on the bottom of the board, with leaded parts on the top side of the board.  I didn’t make a PCB for this one, it is built on pad per hole prototyping board.  Earthing could be a problem, so lots of earth run around the board underneath.  It does look  rather untidy compared to the previous compact transceivers where a PCB was made.  Maybe a PCB later on if it works out ok.
I like the idea of swapping the clock generator outputs to the mixers in software for receive to transmit switching.  It certainly simplifies re-use of the mixers for transmit and receive.

So far the receiver is working fine, with a 0.1 uV minimum discernible signal (MDS).  Still some work to do on software before the transmitter can be tested.  The SSB filter is slightly broader (~ 4kHz wide) than intended although the response shape is good.

The main transceiver and clock generator board is 50mm x 100mm.  With some luck it will fit into a 60mm x 120mm x 35mm enclosure.  It may end up being a hand held type HF radio if things work out.  Of course, it will need a trailing ground if used in this configuration.  There also needs to be some access to the plug in band modules on the enclosure.

20m Compact Transceiver


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New Case for the QRPLabs QCX CW Transceiver

The QCX transceiver was previously packaged in a standard plastic enclosure from Altronics.  The fit was good and the extra space allowed for a battery pack but metal is a better choice for RF.
I was not satisfied with the ergonomics of the controls so I decided to repackage it in an aluminium case.  The HB metal bender was used to make a simple two part case from 1.2mm aluminium sheet.

The case turned out quite well although I elected not to make space for a battery pack this time, and rely on external power.

Finished Case

This layout makes a bit more sense than the original one.

The most used control, the VFO is in the clear and the others further back.  I also turned up new knob for the VFO.

The switches will be set lower into the panel later as the RH one is close to a  trimpot inside the case .

Lid off the case

Here the lid is off the case.  To secure the lid to the base, four 3mm aluminium right angle brackets are fitted to the base and also serve as mounting studs for the board.  The brackets are threaded to accept the 3mm screws for the lid.

A brass shaft extension is added to the rotary encoder.  I may put a bearing in the lid from an old pot later on if play is an issue.

Left side with audio out

Right side with key socket

There is provision on the RHS for a switch to add a cap for operation on 30 metres (the unit is 20 metre).   This works fine for receive and probably needs something added to the LPF on transmit.

Posted in radio communications, SOTA | Tagged , , , , , | 2 Comments

Three Summits around Falls Creek

With nice weather forecast and a day off on Monday, it was an ideal opportunity to do a couple of new summits in the Falls Creek area.  I left home in Melbourne’s South East at 7am on Sunday and took the more scenic route via the Princes Freeway to Bairnsdale and then North through Omeo.
Once past Omeo I took the Bogong High Plains Rd., which was new for me.  This road is sealed and in very good condition although there are many twisting turns so progress is quite slow.

I arrived at the Mt Cope car park at about 1pm., from here, the walk is short (about 1.5km each way) and starts at the Bogong High Plains Rd.  Apart from a ranger posting a sign about upcoming deer shooting at the car park, I didn’t see anyone else.  Mt Cope, VK3/VG-001 at 1837 metres is a 10 point summit.

At the summits, contacts were made on 20m and 40m including a summit to summit with Brian, VK3MCD on Mt. Granya.  ZL, VK1, 2 and 5 call areas were worked.  Cell coverage was good and there were plenty of trees to bungy the squidpole to.
After about 11 contacts, I headed back to the car.

There wasn’t a lot of time left in the day, so I went to Mt. McKay as it is a drive up summit and should not take too long.   Mt McKay, VK3/VE-007 at 1849 metres is a 10 point summit.  Just before the car park on the summit, there was a short pipe sticking out of a rock.  This was ideal to fix the squid pole to, the antenna was unrolled and I set up on the top of another rock.

Two ladies came over and asked what I was doing with the fishing rod and were suprised to hear me talking to ZL1TM.  A summit to summit was made with Peter, VK3ZPF on Mt. Donna Buang.  Most contacts were made on 40m.  ZL, VK2,3 and 5 call areas were worked with some very strong signals.

As it was 4pm, I went south back down the Bogong High Plains Rd. looking for a campsite.  The Raspberry Hill campsite looked ok and it was empty, so I set up there for the night.  As the campsite was at 1600 metres altitude, the temperature dropped sharply at sunset and before long it was hovering at 2 degrees.

In the morning I left the campsite at 8am and drove back up the High Plains Rd. towards Falls Creek for the walk to Mt. Nelse.  The car park for the Big River Firetrail is just short of Falls Creek.  Mt Nelse, VK3/VE-004 at 1882 metres is a 10 point summit.

The walk to Mt. Nelse is about 12 km return.  Most of the walk is along a 4wd track in open plains.  The track goes past the closest point to the summit and then a walking track doubles back to the top.

At the summit, there are the remains of a trig point consisting of a vertical pipe a metre or so long. This makes a good fixture to attach the squid pole.

All contacts were made on 40m within VK2,4, 5, 6 call areas.  By now the wind was  getting up and the chill factor biting, so the kit was packed up and I returned to the car.

Throughout the area, 2m APRS worked very well via Mt. Hotham digipeater.

The trip home was by the same route via Omeo and Bairnsdale, taking about 6 hours including a fuel stop.

Posted in Hiking, SOTA | Tagged , , | 2 Comments

144 MHz for the KX2 Transceiver

Many times I have thought it would be nice to have 2 metres on the KX2, I do miss it from the FT817 days.

This bare board transverter was on Ebay from a Ukraine seller, the feedback was very good and it looked quite compact so for about $35, I ordered one.

Bare Board Transverter

It took about 4 weeks to arrive, but it was over the Christmas break, so probably not too bad.


It measures about 80 x 45 mm, a very suitable size for portable operation.  The power output is stated as 10 to 15 Watts, so not too shabby.

A metal case was then bent up using my home brew metal bender.
A relay switched attenuator

Boxed up

was grafted between the PCB and the transceiver side BNC socket.  I was satisfied that the leads were short enough not to cause a problem.

A 10dB attenuator is fitted to a stand off post to make it level with the relay.  The T configuration attenuator is made from paralleled 0805 SMD resistors so that the power rating is 1 watt.
The KX2 will be set up for about 500mW out so that the maximum drive level of the transverter is easily met.

The KX2 has some nice configuration options to suit transverters.  Parameters such transverter number (you can have several), power output, frequency offset etc. are easily configurable.  In fact, the default configuration was fine.
When powered up, the transverter worked straight off.  Power out was around 10 watts, more should be possible, but will wait until the linearity can be monitored.  Sensitivity seems ample as well.

Connected up


Posted in Projects, radio communications, SOTA | 2 Comments

Mt McLeod VK3/VE-034 SOTA

Mt McLeod was on the unfinished business list after we ran out of day light a couple of years ago when it was summit 3 for the day and decided to turn back.
Kevin, VK3KAB and I decided to have another go, this time as an overnighter rather than a day trip.  We left Melbourne on Boxing day with a leisurely start of 11am and arrived at the fire trail gate on Crystal Brook Rd., off the Mt Buffalo Rd. about 4pm.   This would avoid the heat of the day.
There is very little space to park the car near the gate to the Mt. McLeod Firetrail and thankfully there were no other cars.

The walk took about 2 hrs 30 minutes to the Mt McLeod bush campground.  We had pre booked a campsite there for the princely sum of $13.60 from the Parks website.

The walk is about 8km to the Mt McLeod campground and about 1km further to the Mt McLeod summit (one way).  My pack weighed 19kg, including 5kg of water as we were not sure of water availability.

on the way

There is a signed alternative route to Mt McLeod that avoids a partial section of the firetrail.  This route roughly follows a contour line and avoids a small climb on the firetrail, although I am not sure it was worth it.  The track was a bit overgrown and there were fallen trees in several places.  The alternative route is incorrect on the maps that we had with us, see the plot from the GPS later.

The hike has a lot of ups and downs and with the higher temperatures we had on Boxing day, going was a bit slower than normal.  The campground is just a cleared area near a creek and marshy area with a pit toilet up the hill a bit.  There was ample water supply from the creek, so we could done without carrying 5 litres or so each.  We were the only hikers there and we did not see anyone else during the two days.


Mt McLeod from the campsite

The next morning we arose about 6am and took the radios to the summit.  As the day was predicted to be hot, we thought it best to get an early start and return to the car as early as possible.  Kevin set up a linked dipole from a squid pole on the summit, an I set up the loaded end fed on a mini squidpole tied to a tree.  I qualified on 20m and Kevin on 40m.  Conditions were fairly average.

The walk out was uneventful and took about 2 hrs 15 minutes with temperatures around 30 degrees towards the end.

I must have had my laces loose as my toes took a beating on the many downhill bits with them ending up rather bruised and painful!

After we returned to the car, we drove to The Horn and did a quick activation hand held using the KX2 and the Diamond RHMB2 loaded whip.  There where tourists everywhere so we activated just in the activation zone where the railing starts.


Summit views

Summit views








GPS track

Elevation Profile

Posted in Hiking, SOTA | 4 Comments

Handles for the IC-7200 Transceiver

Grab handles are a good idea for the IC-7200  for when the radio is taken out portable.  The problem is that they cost something like $120 as an accessory!  This is about 10% of the cost of the radio itself.

I had some 5 mm thick Aluminium plate, so out to the workshop to make a set.

firstly, to drill out the handle


Lots of holes were made with the bench drill to make the handle slot.  The inner was then knocked out and filed to shape.  Lots of filing here!

The cleaned up handles prior to painting

The mounting holes are also drilled out for the M4 bolts.  I used cheese head M4x12 bolts for the hole towards the front and M4x16 bolts for the two rear holes.  You could use counter sunk bolts for a better finish.

Next some grey primer was applied as the first coat.


A final 3 coats of flat black paint for a nice finish.
The two rear bolts need a 3mm spacer between the handle and the radio.  These were made from some delrin plastic rod cut to 3mm lengths and drilled out to take the M4 bolts.

The handles fit nicely and should give the radio controls some protection as well when out in the field.

All finished

The look pretty good and saved a bit of cash!

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

Diamond RHM8B Antenna Strain Relief

I came across this interesting part at the Tokyo Radio Fair last month.

It is a BNC strain relief for the popular Diamond RHM8B antenna, particularly when used with a PL259 socket adaptor on an FT-817.  If anyone has one of these antennas, you will know how fragile it is at the BNC plug end.
The strain relief is simply a small plastic tube that provides support to the main shaft of the RHM8B which is then supported by the outer of the PL-259 socket on the FT-817 rear antenna.

This is the coupler or strain relief, not sure what to call it!




The tube simply slides over the main shaft of the RHM8-B as shown below:
Once the tube slides over the PL-259 adaptor, it takes the strain from the flimsier BNC connector which always worries me.

The tube was 500 Yen (~ $6 AUD) at the Radio Fair, the supplier details are on this web link.

It provides some piece of mind in case the antenna is knocked or catches on something.  Of course it will only provide limited protection but it is certainly better than no protection at all.  It might be possible to make one using an electrical conduit coupler from a hardware store, although this unit is a reasonably tight fit at both ends.
Note that I have two PL-259 male to BNC female adaptors and only one was a good fit on the rotating threaded section inside the tube.


The strain relief tube on the back of the FT-817.


Posted in radio communications, SOTA | 2 Comments