Dual Band Handie on the Cheap
Paul Beaumont G7VAK plays with a very cheap but perfectly serviceable handie-talkie from Baofeng.
Paul Beaumont G7VAK plays with a very cheap but perfectly serviceable handie-talkie from Baofeng.
The COVID19 lockdown left many of us with lots of time on our hands. Many turned to watching TV all day but amateur radio, CB and the 446 users saw their chance for experimentation as well as listening or transmitting.
Many older amateurs and radio enthusiasts were taken by the appearance of the ‘cheaper’ handhelds and mobile units that became available from China. Far from being flimsy and poorly made the units seem a good standard and useable without burning a massive hole in your pocket.
One such radio appealed to me. It was advertised as the Baofeng BF-T1 Mini Walkie Talkie covering 400 to 470MHz with 1W output of narrowband FM, Fig. 1.
The price demanded varied between £13.00 to £16.00 for a single unit. Purchasing two at £22 gives an even more favourable price while an order for six means a cost of around £10.50 per unit, and it gets even better as the quantities rise, Fig. 2.
I ordered a single unit costing £12.99, which arrived post-free in a very fast time. Unpacking and eventually switching on, the thing bleeped and addressed me in English for every button push. Thankfully, via the menu key, that prompt and the accompanying bleep can be turned off.
Out of the Box
In the box is the transceiver itself, battery, headphone and microphone assembly with four-section 3.5mm plug, an orange lanyard you’ll never wish to be seen wearing, a small bag with four screws, a belt clip and a USB plug to USB C plug for charging only.
The radio, as I was to discover, cannot be programmed by button selections. The Program 9100 and a programming lead are easily available. The 9100 program can be downloaded and is also available on a miniature CD.
I purchased my 9100 copy online with the 446 Fill already set. Then I overwrote it, using the channels as I saw fit. It is worth bearing in mind that the limit on 446 channels is 500mW and the antenna is likewise modelled to allow very local communications only.
The antenna used on the BF-T1 is very small. Sight of it would remind those who have worked in the non-licensed radio field of the antennas supplied with each transmitter or receiver of the licence free units.
On programming my unmodified unit I noticed something not stated in the advert. The frequency range stated along the bottom of the panel states frequency ranges of 136 to 174MHz and 400 to 470MHz, Fig. 3.
As a result I modified my programming Fill to that seen on my listing, Fig. 4.
It’s notable that the WFM Radio can be programmed to cover 65 to 76 or 76 to 108MHz.
Once programmed I checked the local Caterham repeater GB3NS (channel 10 on the listing as in Fig. 4) as described, 439.6750/430.6750MHz with CTCSS 82.5Hz. The little set was unmodified other than the change of programming. On releasing the transmit pressel I was rewarded with the sound of the repeater carrier, which then closed.
The rough distance as the crow flies between my QTH at Crystal Palace and Caterham is 9.3miles/15km. For 1W and a very poor antenna the result was excellent, Fig. 5a. A local VHF repeater is GB3XP situated in Morden, which is around 4.2miles/6.8km distant, Fig. 5b. Looking at Fig. 4 and Channel 20 the frequencies can be seen as 145.6875/145.0875MHz with CTCSS of 82.5Hz. Attempts to open this repeater failed miserably but with a tiny antenna not configured for the 2m band (and in my opinion pushing it a bit even with 70cm frequencies) this was not a surprise.
Thinking about a Modification
Looking again at Fig. 1, it can be seen the BF-T1 sports a light. A single hi-output white LED with a cheaply silvered reflector would not be much use for finding one’s way around in the dark. I was considering an antenna modification here, reasoning that the removal of the LED would give sufficient room for a socket of sorts.
While I prefer a BNC socket it was obvious there would be no room to fit one easily, if at all, given the size constraints and the necessity of a very firm base.
Looking through my junk box I discovered a single SMA Female Socket
with a pigtail attached and another one that had an SMA Male Plug to BNC Female Socket RF Adaptor, Fig. 6.
Opening the unit is not difficult. The battery is removed allowing the display of the misleading maker’s label, Fig. 7.
Note the small crosshead screws in line with the battery connector. Two others are situated at the bottom of the unit. All four screws can be removed.
Taking the back off can be fiddly. Obviously no damage should occur during this process and I suggest a screwdriver shaft is inserted into one of the holes vacated by one of the top screws and the lid gently lifted from its mount, which brings the motherboard free from the case. Take care not to rip the audio leads from either the board or the miniature loudspeaker.
Once inside I removed the main board easily. Placing in a small vice I unsoldered the small helical antenna from its pad, Figs. 8a and 8b.
Then I set about fixing the SMA female socket. I had no use for the LED Torch and decided that was the best place to fix the SMA receptacle. The LED unsoldered easily enough and I cleaned the small pads to reduce whatever profile they exhibited in the small space available.
Any intention of using the screened low-profile coaxial lead as fitted to the new receptacle was soon squashed. Its diameter was too thick, causing me to remove the outer sheath and the braid, leaving only the central core.
I removed the transparent lens and set it aside. Following this was the silvered reflector. Using my soldering iron, I simply melted a hole into the lens and slowly increased its size with careful use of a small diameter reamer tool. Slipping the SMA receptacle through this access I tightened the lock nut to my satisfaction. Then after mixing a quantity of ‘Ten Minute’ Araldite Resin I packed the space behind the lens and the reflector and then carefully placing the connecting wire, the coaxial core, through the moulding for the lamp assembly, I placed a splodge of resin to hold the lot in place. In keeping with good practice, I used a wipe soaked in methylated spirit to remove any excess. Ten minutes is a good drying time but I left it overnight to be sure, Fig. 9.
In the morning the bond was very strong. The antenna connecting wire was placed along the top of the board, in the unit moulding, and soldered into place.
The battery and rear cover were replaced and after a quick visual check the modified unit, Fig. 10, was switched on. It worked
first time. With a claimed RF output of 500 or 1000mW I didn’t bother tuning it up.
In Use
Fitting a short 2m/70cm antenna I was rewarded with activity on the 446 licencefree channels but also opened and received the Caterham Repeater with no problems.
The Morden repeater, GB3XP, on 2m was another matter. I fitted a longer 2m whip claiming ‘Nagoya 771’ but had difficulty on transmit. Using an SMA/BNC adaptor I connected my stack-mounted 2m/70 colinear. A QSO was in progress and I recognised both parties as being members of the Surrey Radio Contact Club, of which I am a member. I put out a call and was rewarded with RS2/2. Not good but with coaxial losses I was probably putting out around 300mW. No complaints.
The commercial radio side of things worked well for me as I had the misfortune to tune up on LBC with waxing lyrical. I turned back to the repeater.
With 65 to 76MHz also available it occurred to me there may well be other stuff worth catching, either with skip or some other transmissions closer to home.
In Summary
So, are these little units worth their cost? Simply, yes.
The audio is a bit duff and needs taming. Being from a standard IC, sorting this will be the matter of raising the data sheet and the placement of a resistor, or two.
Of course, a simple whip antenna could just be added using a central core of coax and an access hole bored through the antenna moulding to allow this to connect to the existing pad after removal of the existing small helical antenna.
It’s horses for courses here and much dependent on what you wish to achieve. For less than fifteen quid, though, you can’t go wrong!