I think the headline speaks for itself… The usual group, with their Baofengs… Grossly over on the power!
One bit of my equipment that I’ve never looked into is my scanner, a handheld Uniden unit. I got this when Maplin Electronics had them on special offer a few years ago.
Here’s the scanner itself, roughly the same size as a usual HT.
Here the back cover has been removed, and the main RF board is visible at the top of the stack. Unfortunately the shielding cans are soldered on this unit, so no looking under there 🙁
On the right hand side of the board next to the antenna input is the main RF filter network, and it’s associated switching. The RF front end is under the shield closest to the front edge.
On the other side of the PCB is the Volume & Squelch potentiometers, along with a dedicated 3.3v switching supply. An NJM2360A High Precision DC/DC converter IC controls this one. A 3.3v test point is visible next to the regulator.
Here’s the backside of the RF board, some more interesting parts here. There’s a pair of NJM3404A Single Supply Dual Op-Amp ICs, and a TK10931V Dual AM/FM IF Discriminator IC. This is the one that does all the back-end radio functionality. The audio amplifier for the internal speaker & external headphone jack is also on this PCB, top left. A board-to-board interconnect links this radio board with the main control board underneath.
Here’s the front of the control PCB, nothing much to see here, just the LCD & membrane keypad contacts.
And here’s the reverse side of the control board. All the interesting bits are here. The main microcontroller is on the right, a Renesas M38D59GF, a fairly powerful MCU, with onboard LCD drive, A/D converter, serial interface, 60K of ROM & 2K of RAM. It’s 6.143MHz clock crystal is just below it.
The mating connector for the RF board is in the centre here.
There is also a Microchip 24LC168 16KB I²C EEPROM next to the main microcontroller. This is probably for storing user settings, frequencies, etc.
The rest of this board is dedicated to battery charging and power supply, in the centre is a dual switching controller, I can’t figure out the numbers on the tiny SOT23 components in here, but this is dealing with the DC 6v input & to the left of that is the circuitry for charging the NiMH cells included with the scanner.
The last bit of this PCB is a BU2092FV Serial In / Parallel Out 4 channel driver. Not sure what this one is doing, it might be doing some signal multiplexing for the RF board interface. Unfortunately the tracks from this IC are routed on the inner layers of the board so they can’t be traced out.
A while ago I blogged about modifying the output voltage of some surplus Cisco switch power supplies to operate at 13.8v.
Since I was able to score a nice Hammond 1598DSGYPBK ABS project box on eBay, I’ve built one of the supplies into a nice bench unit.
Above is the supply mounted into the box, I had to slightly trim one edge of the PCB to make everything fit, as it was just a couple of mm too wide. Luckily on the mains side of the board is some space without any copper tracks.
These supplies are very high quality & very efficient, however they came from equipment that was force-air cooled. Running the PSU in this box with no cooling resulted in overheating. Because of this I have added a small 12v fan to move some air through the case. The unit runs much cooler now. To allow the air to flow straight through the case, I drilled a row of holes under the front edge as vents.
Here is the output side of the supply, it uses standard banana jacks for the terminals. I have used crimp terminals here, but they are soldered on instead of crimped to allow for higher current draw. The negative return side of the output is mains earth referenced.
I have tried to measure output ripple on this supply, but with my 10X scope probe, and the scope set to 5mV/Div, the trace barely moves. The output is a very nice & stable DC.
This supply is now running my main radio in the shack, and is small enough to be easily portable when I move my station.
Recently I’ve noticed my usual mobile rig, the Baofeng UV-5R, has had very poor receive, and non-existent transmit.
I did a power test on the radio, and confirmed it was still outputting it’s rated RF power. Trying another antenna proved that the radio was fine.
Time to tear down the antenna & see if it can be fixed!
Here’s the antenna, just the factory rubber duckie. As with all these antennas, they’re a compromise between size & their efficiency.
Giving a gentle pull to the antenna sheath while it’s attached to the radio allows it to come apart. The quality actually doesn’t look to bad. It’s very similar in construction to my Diamond X-30, just on a much smaller scale.
At the bottom of the antenna is the matching network, an inductor & ceramic disc capacitor. Here lies the problem with this antenna.
Here where the capacitor joins onto the feedpoint from the SMA connector, the solder joint has come away. This was a very poor joint to start with, and the solder hadn’t wetted the capacitor lead at all
After cleaning the joint, and applying some flux, a new joint was easily made with some Real Solder.
Here’s the joint freshly repaired, the antenna is now back to full working order. It even seems to work better than the others I have 🙂
I’ve always found programming repeaters into the UV-5R manually a bit of an arse, especially since the manual is pretty poor & very concise. Ringway Manchester have done a very good video detailing a simple way to get this done without a computer & most importantly, without any headaches!
Now the final bits have arrived for the SWR Meter module, I can do the final assembly.
Here the SMA connectors are installed on the side of the eBay meter, for forward & reverse power tap.
These are simply tee’d off the wiring inside the meter where it connects to the switch.
The meter is connected to the module via a pair of RG58 SMA leads, above is a readout before calibration, using one of my Baofeng UV-5Rs.
I’m using my GY561 eBay Power Meter as a calibration source, and as this isn’t perfect, the readings will be slightly off. If I can get my hands on an accurate power meter & dummy load I can always recalibrate.
Tools are only as accurate as the standard they were calibrated from!
After calibration, here’s the readings on 2m & 70cm. These readings coincide nicely with the readings the GY561 produce, to within a couple tenths of a watt. SWR is more than 1:1 as the dummy load in the GY561 isn’t exactly 50Ω.
Shortly I’ll calibrate against 6m & 10m so I can use it on every band I have access to 🙂
Here’s some audio from last night on PMR, the regular group seem to be getting a little hacked off 🙂
Onboard the boat we have a small issue with a weak TV signal, and this coupled with a 60′ long run of coax is an issue. Due to the loss in the coax, we’ve lost most of the already weak signal.
To try & solve this issue, I’m fitting a masthead amplifier unit.
These amplifiers are fed power down the same coax that’s carrying the RF signal, and a special power supply is supplied with the amplifier for this. However it’s only 240v AC, no 12v version available.
Here’s the power supply unit, which fits into the coax between the TV & the antenna.
Luckily the 240v supply is easily removable & here has been replaced with a 12v regulator.
There’s not very much inside the shielding can, just a few filter capacitors & an RF choke on the DC feed, to keep the RF out of the power supply system.
The original cable is used, so the supply doesn’t even look like it’s been modified from the outside.
More to come on this when I get the amplifier installed along with the new coax run 🙂
73s
I thought I’d detail the process I use to fit an N-Type connector to a coax cable, as I don’t usually solder these connectors.
Before stripping, fit the backnut, washer & rubber seal onto the cable.
The cable is first stripped back to reveal the shield. This cable has a foil tape as well as the usual copper braid.
Once the inner core has been revealed, the shield washer is fitted. This has a knife edge on the inner diameter, to fit between the outer sheath & the shield, this makes the electrical connection.
With the shield washer fitted, the inner insulation can be cut back, it should be just about level with the final washer when you’re done, this allows the connector to fit together properly.
Trim the center conductor to about double the length required, to allow it to be folded over, as shown. This allows the copper to spring back against the center pin of the connector when it’s fitted, to allow a good connection.
Here the final washer is fitted over the shield washer. The center insulation should be at the same level to allow the center pin to fit properly.
Finally, the center pin is pushed over the inner conductor of the cable, with it’s insulating spacer. Soldering these usually results in the plastic melting and a ruined connector.
Finished plug. Make sure the backnut is tightened fully home, without twisting the connector body itself. After I’m done with the termination, I use self-amalgamating tape to form a strain relief on the cable. This prevents it from breaking at the point where it enters the backnut.
I’ve been terminating these connectors this way for a long time & have not had any issues with SWR or bad connections, dispite the fact that I don’t solder them. This also has the advantage that fewer tools are required for the job & the connectors can easily be reused should the cable wear out.
Here’s a rather unique device for protecting safes & vaults from attack by thefts.
It’s an Aritech VV602 seismic detector, based on piezoelectric sensors. Not surprisingly, this unit is covered in tamper sensors as well. There are several different sensor types in use:
Above is the main unit, with the thermal sensor. This is just a thermal fuse, very commonly used in everything from room heaters to hairdryers. This one triggers at 84°C. The adjustment pot is also visible here.
Above is the magnetic mounting plate used to attach the device to the safe. These units are apparently mounted over the keyhole of the safe to protect the lock, so they need to be easily removable to access the safe. This is a very strong magnet & it isn’t possible to pull it from a metal object without triggering the sensor.
Above is the piezo vibration sensor, bonded to the backplate. When the unit receives vibration or shock, this transducer generates a voltage, which is fed to the control logic below.
Here’s the reverse of the main PCB with the control logic ICs. These are basic logic gates, with a couple of comparators. One of the tamper switches is in the bottom left corner.
Main PCB with the connection terminals. Another tamper switch is in the top left corner, the solid-state relay is under the shield, next to the magnetic tamper switch. (Reed switch).
Some adjustment is provided for sensitivity. I’ve not found much of a difference in sensitivity though when it’s set to different levels.
Magnetic reed switch tamper on the right. Main output solid-state relay on the left under the shield.
This unit was given to me after it apparently went faulty. But on applying power it seems to work fine. Must be those experts again 😉
As per my site update post, I have migrated my radio log onto a new system, from CQRLOG.
CQR log has served me well since I first started in Amateur Radio, however it’s a bit complex to use, requires a backend MySQL server for it’s database, and as it’s a local application, it’s not possible to share my log with other Hams without some difficulty.
The only other major system with an online logging system is QRZ, and I find that particular site a bit of a pain, and many of the features there aren’t free. (Although it’s not horrendously expensive, I’m on a very tight budget & I must save where I can).
Because of these points, I went on a search for something that would better serve my needs. I have discovered during this search that there’s liitle out there in the self-hosted respect.
I did however find Cloudlog, a web based logging system in PHP & MySQL.
This new system allows integration with the main site, as I can run it on the same server & LAMP stack, it’s very simple to use, is visually pleasing and it even generates a Google Map view of recent QSO locations.
It will also allow me to save some resources on my main PC, running a full-blown MySQL server in the background just for a single application is resource intensive, and a bit of a waste of CPU cycles. (CQRLOG and it’s associated MySQL server is 300MB of disk space, CloudLog is 27MB).
Backups are made simpler with this system also, as it’s running on my core systems, incremental backups are taken every 3 hours, with a full system backup every 24 hours. Combined with offsite backup sync, data loss is very unlikely in any event. All this is completely automatic.
I can also take an ADIF file from Cloudlog for use with any other logging application, if the need arises.
Cloudlog is built & maintained by Peter Goodhall, 2E0SQL.
From the looks of Github, there’s also a version 2 in development, although now I have version 1 up & running, I might just stick with it, unless an easy upgrade path is available.
When I am not operating mobile, new QSOs should appear in this system almost immediately, with their respective pins on the map. (These are generated by the Grid Square location, so accuracy may vary).
If you’ve spoken to me on the air & I haven’t updated it, I’m most likely away from an internet connection, in which case your callsign will appear as soon as I have access.
73s for now folks!
Since my new Wouxun has audio output jacks, I figured it would be useful to have the ability to record what my rig hears, if anything interesting comes on the air.
Under Linux, I use an application called, (creatively enough), Audio Recorder.
Using a simple connection to the mic input on a USB soundcard, I can capture everything the radio hears. Unfortunately this doesn’t work for outgoing audio, so it’s not much good at capture of my personal QSOs. For this I will have to set up another radio to act as the main receiver.
At some point in the future I will implement this with a Raspberry Pi as the audio capture server.
GB3MR currently has a big issue with a couple of pirates blocking use of the repeater, and while I’ve not heard anything from them in a few days, today has been much different.
I didn’t manage to get a full recording in this instance, but here’s some of the interference that’s being transmitted. In this case it sounds like there’s a licensed station or two trying to break through but not getting very far. (Sure I heard a callsign or two in there somewhere, whether they’re valid is another thing). Happy listening 🙂
Here’s a sneak preview of my next upcoming project. The target is building a monster DC-DC converter, capable of 70A continuous output, 100A surge.
Here’s the 10 modules, each rated at up to 7A continuous & 10A surge. I ordered so many that they turned up still panelised!
After a few years of running with the same look, I’ve decided on some changes.
Finally there have been some behind the scenes changes to implement some better security on site.
Getting the number of hits I do per day, this site gets attacked by the Internet’s Great Unwashed on a regular basis. No attack has ever been successful but more security never hurts!
73s folks!
The latest addition to my radio shack is the GY561 frequency & power meter, which has already come in useful for measuring the output power of all my radios.
It’s a small device, roughly the same size & weight as a stock UV-5R. Power is provided by 3 AAA cells.
The display is a standard HD44780 8×2 module. The display on this unit isn’t backlit, so no operating in the dark.
The cover pops off easily to allow access to the internals, without having to remove any screws!
The 4 screws on the back of the unit hold the heatsink plate for the 50W 50Ω dummy load resistor.
Removing the cover reveals a couple of adjustments, for frequency & RF power calibration.
There are also 3 tactile switches that aren’t on the front panel. According to the manual (which in itself is a masterpiece of Chinglish), they are used to software calibrate the unit if an accurate RF power source is available. I will attempt to do a reasonable translation when time allows.
Disassembly further than this involves some desoldering in awkward places, so a search of the internet revealed an image of the rest of the internal components. In the case of my meter, all the part numbers have been scrubbed off the ICs in an attempt to hide their purpose. While it’s possible to cross-reference IC databooks & find the part numbers manually, this process is a time consuming one. Luckily the image I managed to locate doesn’t have the numbers scrubbed.
Under the LCD is some 74HC series logic, and a prescaler IC as seen in the previous frequency counter post. However in this unit the prescaler is a MB506 microwave band version to handle the higher frequencies specified.
In this case however the main microcontroller is an ATMEGA8L.
This is complemented by a SN54HC393 4-bit binary counter for the frequency side of things. This seems to make it much more usable down to lower frequencies, although the manual is very generous in this regard, stating that it’s capable of reading down to 1kHz. In practice I’ve found the lowest it reliably reads the frequency input is 10MHz, using my AD9850 DDS VFO Module as a signal source.
It did however read slightly high on all readings with the DDS, but this could have been due to the low power output of the frequency source.
Just like the other frequency counter module, this also uses a trimmer capacitor to adjust the microcontroller’s clock frequency to adjust the calibration.
The power supply circuitry is in the bottom left corner of the board, in this case a small switching supply. The switching regulator is needed to boost the +4.5v of the batteries to +5v for the logic.
Also, as the batteries discharge & their terminal voltage drops, the switching regulator will allow the circuit to carry on functioning. At present I am unsure of the lower battery voltage limit on the meter, but AAA cells are usually considered dead at 0.8v terminal voltage. (2.4v total for the 3 cells).
When turned on this meter draws 52mA from the battery, and assuming 1200mAh capacity for a decent brand-name AAA cell, this should give a battery life of 23 hours continuous use.
On the back of the main PCB is a 5v relay, which seems to be switching an input attenuator for higher power levels, although I only managed to trigger it on the 2m band.
Finally, right at the back attached to an aluminium plate, is the 50Ω dummy load resistor. This component will make up most of the cost of building these, at roughly £15.
On my DVM, this termination reads at about 46Ω, because of the other components on the board are skewing the reading. There are a pair of SMT resistors, at 200Ω & 390Ω in series, and these are connected across the 50Ω RF resistor, giving a total resistance of 46.094Ω.
This isn’t ideal, and the impedance mismatch will probably affect the calibration of the unit somewhat.
The heatsinking provided by the aluminium plate is minimal, and the unit gets noticeably warm within a couple of minutes measuring higher power levels.
High power readings should definitely be limited to very short periods, to prevent overheating.
The RF is sampled from the dummy load with a short piece of Teflon coax.
There’s a rubber duck antenna included, but this is pretty useless unless it’s almost in contact with the transmitting antenna, as there’s no input amplification. It might be handy for detecting RF emissions from power supplies, etc.
For the total cost involved I’m not expecting miracles as far as accuracy is concerned, (the manual states +/-10% on power readings).
The frequency readout does seem to be pretty much spot on though, and the ability to calibrate against a known source is handy if I need some more accuracy in the future.
I’ve also done an SWR test on the dummy load, and the results aren’t good.
At 145.500 MHz, the SWR is 3:1, while at 433.500 it’s closer to 4:1. This is probably due to the lower than 50Ω I measured at the meter’s connector.
These SWR readings also wander around somewhat as the load resistor warms up under power.
I’ll probably also replace the AAA cells with a LiPo cell & associated charge/protection circuitry, to make the unit chargeable via USB. Avoiding disposable batteries is the goal.
Following on from the earlier power tests on my Baofeng HTs, here’s the readings from the Wouxun KG-UV950P. Power is a little lower than specified, but this is probably due to the supply voltage being a bit less than 13.8v. These readings were taken at a supply voltage of 12.88v.
The same frequencies were used, 145.500 & 433.500 for the VHF/UHF tests. For the 6/10m tests 27MHz & 50MHz were used.
The power meter was connected with 1 metre of RG58 dual-screened cable with N-type connectors.
High
6m: 24W
10m: 23W
VHF: 38W
UHF: 24.9W
Medium-High
6m: 10.9W
10m: 9.3W
VHF: 19W
UHF: 14.2W
Medium-Low
6m: 6.8W
10m: 3.5W
VHF: 9.6W
UHF: 9.4W
Low
6m: 3.5W
10m: 1.9W
VHF: 4.8W
UHF: 4.7W
I’ve noticed that the RF power output from the Chinese radios can be quite variable from model to model, and even from individual radios of the same model & batch.
I’ve bought an RF Power meter (GY561) to do some tests on the HTs I have at present.
All tests were performed with the radio fully charged & still on the charging base, to make sure the supply voltage remained constant at 8.4v throughout the tests.
Frequencies used were 145.500 & 433.500 for VHF & UHF respectively.
The power meter was connected with ~8″ of RG174 Coax.
High Power:
UV-5R 1 (S/N: 13U1136132):
VHF: 6.3W
UHF: 4.9W
UV-5R 2 (S/N: 13U1136114):
VHF: 6.5W
UHF: 5.2W
UV-5R 3 (S/N: 130U541416):
VHF: 7.1W
UHF: 6.3W
Low Power:
UV-5R 1 (S/N: 13U1136132):
VHF: 2W
UHF: 1.2W
UV-5R 2 (S/N: 13U1136114):
VHF: 2.3W
UHF: 1.5W
UV-5R 3 (S/N: 130U541416):
VHF: 2.7W
UHF: 2.1W
Thanks to Lewis, M3HHY for lending me this one 🙂
Here’s a quick look at a Sainsmart frequency counter module. These are useful little gadgets, showing the locked frequency on a small LCD display.
It’s built around an ATMega328 microcontroller (µC), and an MB501L Prescaler IC. The circuit for this is very simple, and is easily traced out from the board.
Here’s the back of the board, with the µC on the left & the prescaler IC on the right. This uses a rather novel method for calibration, which is the trimmer capacitor next to the crystal. This trimmer varies the frequency of the µC’s oscillator, affecting the calibration.
Input protection is provided by a pair of 1N4148 diodes in inverse parallel. These will clamp the input to +/-1v.
The prescaler IC is set to 1/64 divide ratio. This means that for an input frequency of 433MHz, it will output a frequency of 6.765625MHz to the µC.
The software in the µC will then calculate the input frequency from this intermediate frequency. This is done because the ATMega controllers aren’t very cabable of measuring such high frequencies.
The calculated frequency is then displayed on the LCD. This is a standard HD44780 display module.
Power is provided by a 9v PP3 battery, which is then regulated down by a standard LM7805 linear regulator.
I’ve found it’s not very accurate at all at the lower frequencies, when I fed it 40MHz from a signal generator it displayed a frequency of around 74MHz. This is probably due to the prescaler & the software not being configured for such a low input. In the case for 40MHz input the scaled frequency would have been 625kHz.
I have recently come across the software the Wouxun factory uses to set the band limits on the KG-UV950P.
While the software is in Chinese, it’s functional, and allows setting of all band limits on the radio.
Here’s an English version of the interface:
Note when using this software:
This possibly has the potential to damage the radio, if you transmit on a frequency it’s not designed for. Not to mention the legal issues with transmitting on frequencies that aren’t permitted! Use at your own risk!
Recently I decommissioned some networking equipment, and discovered the power supplies in some switches were single rail 12v types, with a rather high power rating. I figured these would be very good for powering my Ham radio gear.
They’re high quality Delta Electronics DPSN-150BP units, rated at a maximum power output of 156W.
These supplies have an adjustment pot for the output voltage regulation, but unfortunately it just didn’t have quite enough range to get from 12.0v to 13.8v. The highest they would go was ~13.04v.
After taking a look at the regulator circuit, I discovered I could further adjust the output voltage by changing a single resistor to a slightly lower value.
Firstly though, a little background on how switched mode power supplies operate & regulate their output voltage.
Here’s the supply. It’s mostly heatsink, to cool the large power switching transistors.
The first thing a SMPS does, is to rectify the incoming mains AC with a bridge rectifier. This is then smoothed by a large electrolytic capacitor, to provide a main DC rail of +340v DC (when on a 240v AC supply).
Above is the mains input section of the PSU, with a large common-mode choke on the left, bridge rectifier in the centre, and the large filter capacitor on the right. These can store a lot of energy when disconnected from the mains, and while they should have a discharge resistor fitted to safely drain the stored energy, they aren’t to be relied on for safety!
Once the supply has it’s main high voltage DC rail, this is switched into the main transformer by a pair of very large transistors – these are hidden from view on the large silver heatsinks at the bottom of the image. These transistors are themselves driven with a control IC, in the case of this supply, it’s a UC3844B. This IC is hidden under the large heatsink, but is just visible in the below photo. (IC5).
Here’s the main switching transformer, these can be much smaller than a conventional transformer due to the high frequencies used. This supply operates at 500kHz.
After the main transformer, the output is rectified by a pair of Schottky diodes, which are attached to the smaller heatsink visible below the transformer, before being fed through a large toroidal inductor & the output filter capacitors.
All this filtering on both the input & the output is required to stop these supplies from radiating their operating frequency as RF – a lot of cheap Chinese switching supplies forego this filtering & as a result are extremely noisy.
After all this filtering the DC appears at the output as usable power.
Getting back to regulation, these supplies read the voltage with a resistor divider & feed it back to the mains side control IC, through an opto-isolator. (Below).
The opto isolators are the black devices at the front with 4 pins.
For a more in-depth look at the inner workings of SMPS units, there’s a good article over on Hardware Secrets.
My modification is simple. Replacing R306 (just below the white potentiometer in the photo), with a slightly smaller resistor value, of 2.2KΩ down from 2.37KΩ, allows the voltage to be pulled lower on the regulator. This fools the unit into applying more drive to the main transformer, and the output voltage rises.
It’s important to note that making too drastic a change to these supplies is likely to result in the output filter capacitors turning into grenades due to overvoltage. The very small change in value only allows the voltage to rise to 13.95v max on the adjuster. This is well within the rating of 16v on the output caps.
Now the voltage has been sucessfully modified, a new case is on the way to shield fingers from the mains. With the addition of a couple of panel meters & output terminals, these supplies will make great additions to my shack.
More to come on the final build soon!
Earlier today, one of my neighbours put their dishwasher out for the scrap man. After asking if I could appropriate it in the interest of recycling the Ham Way™, I was told it wasn’t draining. The engineer called out to fix it had claimed it was beyond economical repair.
A quick test showed that indeed the drain pump wasn’t operating correctly – very poor pumping capacity & a horrid grinding noise.
Here is the drain pump on the bottom of the machine. Strangely for a dishwasher, everything underneath is very clean & free from corrosion.
On removing the securing screw & unlatching the pump from it’s bayonet mount, the impeller instantly tried to make a break for freedom – it has come off the splines of the rotor shaft.
In the past I’ve tried to remove these rotors manually – and totally destroyed the pump in the process. They are usually so well secure that replacement is the only option. This particular one must have vibrated off the shaft somehow.
This repair was easy – removing the rotor from the main pump body & gently drifting the impeller back onto the splines.
Here the pump is reassembled & ready for reinstallation.
On test the pump sounds normal, & works as expected.
Engineer 1 : 0 Throwaway Society
I recently posted about a small analog SWR/Power meter I got from eBay, and figured it needed some improvement.
After some web searching I located a project by ON7EQ, an Arduino sketch to read SWR & RF power from any SWR bridge.
The Arduino code is on the original author’s page above, his copyright restrictions forbid me to reproduce it here.
I have also noticed a small glitch in the code when it is flashed to a blank arduino: The display will show scrambled characters as if it has crashed. However pushing the buttons a few times & rebooting the Arduino seems to fix this. I think it’s related to the EEPROM being blank on a new Arduino board.
I have run a board up in Eagle for testing, shown below is the layout:
The Schematic is the same as is given on ON7EQ’s site.
Update: ON7EQ has kindly let me know I’ve mixed up R6 & R7, so make sure they’re switched round when the board is built ;). Fitting the resistors the wrong way around may damage the µC with overvoltage.
Here’s the PCB layout. I’ve kept it as simple as possible with only a single link on the top side of the board.
Here’s the freshly completed PCB ready to rock. Arduino Pro mini sits in the center doing all the work.
The link over to A5 on the arduino can be seen here, this allows the code to detect the supply voltage, useful for battery operation.
On the right hand edge of the PCB are the pair of SMA connectors to interface with the SWR bridge. Some RF filtering is provided on the inputs.
Trackside view of the PCB. This was etched using my tweaked toner transfer method.
Here the board has it’s 16×2 LCD module.
Board powered & working. Here it’s set to the 70cm band. The pair of buttons on the bottom edge of the board change bands & operating modes.
As usual, the Eagle layout files are available below, along with the libraries I use.
[download id=”5585″]
[download id=”5573″]
More to come on this when some components arrive to interface this board with the SWR bridge in the eBay meter.
There are times when I am frequently away from home base, usually either on the canal system or at a festival. During these times it’s very handy to be able to just grab a bag, without having to be concerned about sorting everything out.
This post will only detail the portable shack bag. The power supply kit that goes along with it with be detailed in another post.
The bag I use is an VHS Camcorder bag from the early 80’s. It’s very well built, & copes easily with the weight of all the radio gear.
Total weight for this system is 13.4lbs (6kg).
Above is the bag packed. Obligatory International Ameteur Radio Symbol patch front & centre. Being an old camera bag, this easily slings over the shoulder, with it’s padded strap.
Here is all the current equipment laid out. All the equipment to enable me to set up a station anywhere.
In the following photos I will go into the details.
First off, my main radio. This is the same Wouxun KG-UV950P mobile rig I have posted about previously. I have heatshrunk the power cable to keep it together & attached my standard power connector to the end. More on these later on.
In the bag I also carry three Baofeng UV-5R handhelds. Extremely useful for short range site communications, along with their charger bases. The charging base on the right has been slightly modified to support charging of my main LED torch as well, which uses similar Li-Ion based packs as the Baofengs.
As the charger bases for the Baofeng HTs take a supply of 10v DC, I have constructed a 12v adaptor system for them. (Which utter prat of an engineer at Baofeng picked 10v?)
Also included is a small Alinco ELH-2320 35W 2m linear amplifier. This was given to me from the local HackSpace in Manchester. (They don’t have any ham members, besides myself). Also here is my small SWR & Power meter, SDR kit & a pair of syringes. These are filled respectively with Copaslip copper loaded grease, (very good for stopping fasteners exposed to the weather from seizing up), and dielectric silicone grease. (I use this stuff for filling connectors that are exposed to the weather – keeps the water out).
I always keep essential tools in the bag, here is the small selection of screwdrivers which fit pretty much any screw fastener around, my heavy-duty cable shears (these buggers can cut through starter cable in one go!) and my trusty Gerber Diesel multitool.
Main antenna magmount & a spare Raspberry Pi.
Finally, the antennas for the HTs, main dual-band antenna (Nagoya SP-45) for the magmount, a small selection of spare plugs, sockets & adaptors. Also here is a roll of self-amalgamating tape, very handy for waterproofing wiring connections (especially when used in conjunction with the silicone grease), & a roll of solder wick.
Now, the main power connectors of choice for my equipment are Neutrik SpeakOn type connectors:
These connectors have many advantages:
Also, they have two pairs of pins – and as some of my bigger non-radio related equipment is 24v, this allows me to use a single set of plugs for everything. Without having to worry about plugging a 12v device into a 24v socket, and letting out the magic blue genie.
Once everything is packed up, here’s the bag:
Everything has a neat little pocket for easy access. Some closeups below.
I will post more about my portable power system later on, as this bit of my kit is being revamped at the moment.
Stay tuned!
In my original review, I noted that this radio was supplied with a SO-259 socket for the antenna connection.
However I’m less than fond of these, due to their non-constant impedance, which can cause signal loss issues at VHF/UHF. Because of this, I’ve replaced it with a high quality N-type connector. These connectors are much better, as they are a constant 50Ω impedance, they’re weather resistant, and being rated to 11GHz, are more than sufficient for a radio that will only do up to 70cm.
Here can be seen the point where the connection is made to the PCB.
I’ve already replaced the socket in this photo. The pair of solder pads either side of the central RF point were soldered to wings on the back of the original SO-259. As there are a pair of screws, also connected to the ground plane, there have been no signal issues with just using the frame of the radio as the ground point. Shown below is the original socket, with the ground wings.
Finally, here is the back of the radio with it’s shiny new N connector.
Chassis mount connectors are pretty standard, so this new connector fits perfectly into the same recess of the original. Looks like factory fitted!
I am now standardising on N connectors for everything in my radio shack, next on the project list for conversion is the SWR meter I recently acquired.
Stay tuned for more!
