Mark, Pantenneman looks into the possibility of using Chinese PMR Handhelds for a UHF CB style service.
As noted in previous reviews, the availability of Chinese imported handsets is alarmingly easy in the age of online buying from the likes of eBay. Normally, these handsets are bought for the use of a cheap handheld rig to use on the 2m / 70cm amateur radio bands, in comparison to the likes of the Yaesu FT-60, Kenwood TH-F71E and the like. And as noted before, they are alarmingly good value for money in the likes of the Puxing PX777 Plus reviewed here. Please note that this review is not of an overly scientific or technical basis, they were tested in real life conditions and not in some library with a bunch of computers and alleged theory.
However, for this review in question the context is the use of these radios (UHF models only in this case) as a “super range” PMR446 alternative that can be modified very easily to accept home brew antennas cut for the PMR446 frequencies, and as a theoretical alternative usage to 27mhz CB, a UHF CB service similar to that used in Australia or GMRS/FRS in the United States. Please note, that the usage of these radios on the PMR446 frequencies if of a dubious legality in the UK without going into too much detail. So, caution is advised!
The Puxing PX777 Plus that I own in question were sourced from eBay for the grand total of £84 for the pair (£42 each), which, for a wideband 400-470mhz capable transceiver is alarmingly good value for money compared to an equivalent Ham Radio VHF/UHF handheld rig, without the restriction of being limited to the Ham Radio frequencies. But, in the context of a PMR446 handheld, is somewhat expensive unless you compare this with high end PMR446 transceivers. This may deter some users that want a handset that is better than the average “toy” PMR446 handheld.
Exactly one week (seven days including weekends) elapsed before I got the handhelds. The eBay order was actually placed sometime in the evening at home, and they were delivered to my work address at sometime like 1600hrs. I can honestly say that the delivery was alarmingly quick from Hong Kong into the UK and all arrived in one piece without a hitch. Basically, pick an eBay seller that has a decent feedback rating and all should be fine. I have ordered phone accessories from Hong Kong and have had similar postage arrival times and have been very pleased in the past.
Setting up, and functions
As described in the Chinese handheld review, the Puxing suffers from the same “Engrish” manual in dodgy translated English. However, if you have the likes of a scanner radio like a Yupiteru, GRE, etc then you won’t find too many problems and you will be instantly at home and figure everything out within a short space of time.
Functions are accessed via the MENU buttons on the front, with the numerical keypad accessing the most used functions. The settings are also available via the rotary encoder nearest the antenna (which acts as the VFO/Channel Select)/ The Puxing is switched on via the Volume dial, which also acts as a click stop on/off switch to power the unit down. The transmit button is located on the left hand side, with a red button acting as a call ring, which sends a ringing tone to the other handset as equipped on a PMR446 handset. Also, there is a “Moni” (monitor) button on the side which opens the Squelch so that you can monitor a weak signal. The antenna is approximately 12.5cms, and is connected via an SMA style plug.
The functions are as follows:
Scan – Scans through the memory channels (MEM), or through its frequency range (VFO) as defined by the user. Also with a “priority” channel similar to that of a scanner. Frequency steps in VFO mode are -5, 6.25, 10, 12.5, 25khz. It must also be noted that the scanner easily doubles up as an effective UHF band scanner radio too, which performed very well indeed despite this not being the handheld rigs original intention. It’s certainly nice to know it can be used as such though.
VOX – The level of voice actuation if the user chooses to plug in a hands free set, enabling the user to not have the need to touch the PTT key.
Squelch – This has a variable level from 0 through to 10, with 5 being the factory default
Power – Adjusts the transmit power to 5w, or 0.5w (theoretical figure).
Scrambler – Enables the user to add “Voice Inversion” scrambling to their transmitted audio. The effects of this are similar to listening to a sideband transmission on a Ham Radio set with the wrong mode selected. It must also be noted that the scambling facility is of dubious legality on either the PMR446 bands or the Ham Radio bands (where scambling your audio is strictly out of bounds). This could attract attention, as Offcom could take a dim view of this. Especially in this post 9/11 climate where terrorist paranoia is rife (as they could assume you were a terrorist on the basis of scrambling your transmissions). Just something to bear in mind.
LED – Selects illumination of the display to permanently on, automatically time out, and off.
Light – Selects three different colours of display, blue, light purple, or amber.
Beep – Selects key beep on or off
ANI – Automatic Number Idenification. Gives the hanset an ID that flags up on the display when the other user transmits
Split frequency operation modes – enabling the user to transmit on one frequency and receive on other, for repeater access (Ham Radio use only, so I shall not go into too much detail in the context of this review)
CTCSS / DCS settings – Set the appropriate CTCSS / DCS codes for your handhelds so that no one jumps into your transmission. The user has to set all the handhelds to work on a certain CTCSS / DCS code otherwise no one in the group will hear you if they are set incorrectly. The user has to program a frequency in with a certain code into the units memory.
Wide / Narrow Sets audio deviation to wide or narrow. Narrow deviation is recommended in busy areas on PMR446 as it may cause bleedover/splatter onto other channels.
The build quality of these handsets is very good and sturdy, with a nice compact feel that look “the business” compared to the average PMR446 handheld rig. The battery slips onto the back and can be removed by pressing down on two clip releases either side of the handheld, with higher capacity batteries available from online sources. The display is quite attractive and nicely laid out, using various easy to read symbols to designate what the set is doing. The biggest plus is the signal meter below the frequency readout, which goes all the way to the end under transmit under high power, and half way across under low. In all honesty, I did find the signal meter somewhat optimistic, but it gives a good indication of received signal strength which you didn’t have on a normal PMR446 handheld. Half of the channels that were programmed into the handheld rig were in the GMRS/FRS range (462 mhz) as used in North America, with what seemed like half of the channels corresponding to the same frequency allocations as used over there.
Charging the units before use
The charger supplied is 220v, which will work on the UK’s mains system of 230v. However, the chargers are of a European two pinned variety which will require a shaver adapter (two pin into three pin) converter which you will have to source yourself.
I have also noticed a small design fault with the handhelds, where they may have issues connecting into the docking unit that charges them. A wipe of the contacts on the back of the handheld and the docking unit with a cloth will help matters if there is an intermittent connection. The chargers light up green once charging has completed, and light green when charging is completed and stop charging (the charger then goes cold, probably down to a simple thermal cut out circuit). Charging fully took around 4-6 hours, and the handsets (broadly speaking) last 3 days before another charge. Similar to that of a Nokia N70 mobile phone.
The short range test under “Low Power”
The tests for short range where carried out in my girlfriends neck of the woods, a small town that is based in the Merseyside area over the weekend, which has generally has flat terrain and in a high up location, going to a steep downhill climb upon exiting the town into the Liverpool area.
What was immediately striking with these handhelds was the vastly superior transmitted audio when set to wide deviation. They sounded very precise, clear, with a decent amount of treble and bass to both the transmitted and received audio, in comparison to my “kosher” Tevion PMR446 handheld rigs. In narrow deviation, the transceived audio quality was lower, more “closed in” and lacking in high treble and sounded muggier in comparison. It must be noted, that in wide deviation it may cause splattering and bleedover to other PMR446 users which may draw attention to your transmissions.
The general range that we discovered with these handhelds under low power was around 2.5miles on foot without any break up in signal, although at one point there was slight breaking up of the signal with slight flutter caused by obstructing nearby buildings at the fringes of this range (the signal report was mostly RST559, with the worst reading at RST559). My long suffering girlfriend was quite impressed with the potential of these handsets, as she theorised that these could easily be used to speak to two nearby friends of hers without the need of mobile phones and texting (which, in the short range test can be worked with conventional PMR446 handhelds, however, further study with my Tevion handhelds is needed in this case). The Tevion handhelds, however, suffer from fluttering reception at around 1.7 miles, and deteriorating rapidly at 2.25 – 2.5miles dependant upon various obstructions and terrain while used in my home town. The range of the Puxing under low power I believe would be approximately 3-3.5miles in a town setting, with 4miles at the most in an open surrounding.
The long range test under “High Power”
I decided to test these handheld rigs in the high power setting. No outdoor antennas were used on either handheld, with one handheld in the upstairs floor of the house while the other was used by a test subject in a car, static mobile, with the antenna peaking out of the car window. The town in question is a small town that has a green belt amongst the housing estates with various hills, with an industrial estate on the outskirts of the town, connecting with a large motorway.
In that day, the test subject drove 4 miles down the road from my house with the other Puxing out of the pair, The test subject was worked on a perfect RST557-RST559 with no noticeable deviation in signal by either user, testing for differences in signal by walking downstairs into the kitchen.
A second test involved driving to a nearby large shopping centre, with the mobile control subject parked on the top floor of a three tier multi storey car park. I believed that the control subject may be impossible to work, as tests were tried on foot from my house to the shopping centre with the Tevion handheld rigs which lost signal completely, only being obtainable by very broken speech or the call tone button being pressed/ The test subject disagreed with me, and believed that I could be worked.
He was right!
The test subject boomed out from the top floor of the multi storey car park with ease, with a signal report of RST599, perfectly intelligible. The next test involved the mobile test subject trying from the outskirts of town, to a distance of 6.5 miles away from my home location. This time, his signal was RST558 / RST 555, fluttering and instability of signal kicked in when the subject was mobile, due to the large motorway on the outskirts being higher up than the mobile test subject with impaired the signal, finally becoming lost below the squelch threshold approaching the motorway. However, when the test subject drove underneath the motorway bridge and up a hill back home, the signal began to improve to a RST559, with flutter when going under bridges or passing by tall buildings. The general range I believe is 6.5 – 7 miles, with a maximum of 12.5 – 15 miles out in the open handheld to handheld. As seen on a infamous YouTube video online by a certain forum member.
Conclusion, and the use of imported Chinese handhelds as “UHF CB”
The experiences that I have had with these handhelds has been fascinating to say the least. Because of the ability to adapt the rigs to external antennas, it brings along a lot of interesting possibilities. Notably the use of PMR446 has a form of “UHF CB Freebanding”, especially if you programmed the handheld rigs with the “other” 8 channels designated for digital PMR446, from 446.106.25mhz – 446.193.75mhz and using various combinations of CTCSS / DCS, as well as the existing PMR446 channels into the handheld rig. This may also be necessary in busy cities due to numerous shops and various businesses taking use of the licence free aspect of PMR446 as the channels are usually overcrowed, CTCSS/DCS codes would be necessary at least.
The only concern with such a handheld rig is the fact that a novice user can transmit randomly throughout the range of 400-470mhz, invading legitimate users of the frequencies that were there in the first place. However, the technologically savvy user would be a lot more careful and would ensure that they didn’t cause any undue interferance to other users.
Using a suitable resonant vertical antenna, or a beam, I believe that it would lend itself very well. This UHF allocation lends itself very well as a service that could have a maximum radius of 10-20miles with approximately 5-10watts ERP, as it’s immune to the effects of Sporadic E propagation and Sunspots / Solar Flares witnessed on 27mhz. The frequencies would be perfect for what CB was supposed to be intended for, a short range communication service to the public. The antennas would be quite small, being no bigger than 34cms (approx) as a dipole, and as a Yagi beam style antenna would look physically no different than a UHF TV antenna seen on many a rooftop of a householder in the UK. Perhaps, small scale repeaters could be used in built up areas to improve reception, similar to that used by Radio Hams. I believe that the UK has missed a trick here, and perhaps should have used this range as opposed to 934mhz (which, I am lead to believe has yet to be used by mobile phone networks, despite most sources saying otherwise). If only we did have a UHF CB service, as it would attract a reasonably quantity of radio users as experienced in the U.S. and Australia, and be a very efficient service.