The QYT KT-7900D

But is it any good?

As you might have noticed, I am now a freshly licensed radio amateur.  As such I do need a transceiver or two in order to get on the air.  This is the story of one of my new radios.

I have a limited discretionary budget to use for my new hobby, and I have to say from the outset that my lovely wife has been very supportive.  As such, I want to try and get the best value for our money.  One evening I stumbled upon this little item on Banggood for a little over $A150 including shipping.  Covering both 2m and 70cm bands with a claimed 20W output it seemed almost too good to be true.  I bought one.

About ten days later a tiny package arrived for me.  At just 98mm x 43mm x 126mm the photos don't convey quite how small it actually is.  The entire case serves as a heatsink so it is heavier than it looks, but certainly not bulky.

The standard power cable comes with a cigarette lighter plug.  As I intended to run it from home using a regulated PSU, I just cut the plug off, which according to Banggood voids the warranty.  You have been warned.

Operation

There is nothing in the way of technical details available unfortunately, and as it is brand new, I am loathe to disassemble it.  As and when I find more information I will update this article. 

Into a dummy load, my Daiwa Power Meter showed 10W (on the 10W setting) as claimed.  I did not test it at high power, because (a) I'm not licensed for that and (b) my load is rated at 15W only.

Connected to my home-made 2m dipole it easily pulls in the VK2WI (Dural) and VK2RNS (North of Hornsby) repeaters, which from my location at the base of a ridge is good news.  Reception on 70cm is less impressive, but at least it does work.

Audio is clean and the front panel display, while only 1.8" is very easy to read.  The keypad on the microphone allows you to directly enter a frequency, and gives you access to the menu system.  I did find it's not always easy to get the microphone to stay plugged in.  I rolled back the flexible cover from the plug and that improved things a lot.

I have read others complain that the receiver is easily overloaded.  I have not experienced this issue, so perhaps the sensitivity is doing me more good than harm at my present location.

On transmit, audio is clear.  I'm presently limited to 10W but it still succeeds in opening repeaters without fuss.

The menu system when accessed using the keypad is nothing short of horrid.  The manual must be based on an earlier version of the firmware because it was nothing like the menus I had to deal with.  Trying to set up the CTSS tone for my local repeater was just plain hard.

However, there is a solution.  The manufacturer has control software which means you don't need to fight with the keypad any more.  It only works with Windows, but if you use a Mac or Linux I am told that "Chirp" now supports this unit.

A gripe about the official software:  Why, in this day and age does it need admin privilege to run?  Plenty of other apps can control serial ports without being admin so this seems unnecessary to me.  You will also need to wire up your own data cable, but when you get past these issues, it just works.  Once you have set up your basic needs with the software, then it is easy to just scroll through frequency selections and you need not bother with the keypad for normal operations.

Making a serial cable

Like a lot of small transceivers, the KT-7900D uses the mic/speaker sockets for control.  You will need a regular USB to Serial module, preferably not with an FTDI chip because they are getting problematic these days.  A standard T-R-S (Tip-Ring-Sleeve) plug is also required.  Make sure the module has 5V I/O, and connect it as follows:

TIP -> Serial RxD

RING -> Serial TxD

SLEEVE -> Ground

In summary

The good

• It's cheap.  Not pocket money cheap, but pretty close.
• Receiver is more than sensitive enough for local operations.
• It meets the claims for transmit power.

The bad

• Inbuilt speaker is very tinny.  An external speaker, perhaps with some filtering might help.
• Those menus are just awful.
  
• Chassis can get quite warm with long operation.
  

Conclusion

If you want the performance of an Icom or a Yaesu rig then you'd best skip the KT-7900D and keep saving.  It shows in places where the 7900D has been built down to a price, but honestly, what did you expect?

I've read plenty of negative things about these sets online, but to be honest I can't complain about the quality or on-air performance, at least in my limited usage.  I probably would not buy another one if mine were to vanish, but I am happy I got my money's worth out of it.