What is the serial number of my QCX-mini kit?
What is the tuning range of the VFO?
What is the current consumption of QCX-mini?
Is there a version enforcing Japanese band limits?
When will my kit be sent, when will it arrive, etc etc.?
Will I get the latest firmware version when my kit ships?
What technical support is available?
What are the dimensions of the PCB?
Are other bands possible?
Is a multi-band QCX-mini possible?
The RF power output is lower than expected
What wire gauge is used in the QCX-mini?
The volume is too loud...
The parts list says the potentiometer is logarithmic. But the supplied one is linear...
QCX-mini kits are normally sent within 1 business day, as long as everything is in stock. If there is any shortage, it will be noted on the ordering page.
QCX- serial numbers are not in the shipment notification emails or packaging. You can find your serial number in the list of Order IDs vs Serial Number on the QCX Serial number page. Note that QCX serial numbers started from 1, QCX+ serial numbers continued on up from the serial number of the last QCX, and QCX-mini serial numbers are also allocated sequentially in the same sequence; therefore the QCX-mini serial number that you receive is from a sequential list of serial numbers that includes all members of the QCX family (QCX, QCX+ and QCX-mini).
The QCX-mini kit uses synthesized tuning using an Si5351A kit. Tuning covers the entire amateur band (not just the CW section). Technically, there is a limit imposed by the way the Si5351A chip is configured to produce quadrature (90-degrees phase shift) on two of its output pins. The tuning ranges are as follows:
80/60/40m: 3.2 MHz to 9.1 MHz
30m: 4.8 MHz to 13.7 MHz
20m: 6.3 MHz to 18.0 MHz
17m: 8.4 MHz to 24.0 MHz
15m: 10.1 MHz to 28.8 MHz
12m: 11.9 MHz to 33.8 MHz
10m: 14.5 MHz to 41.1 MHz
Practically speaking, the Band Pass Filter attenuates the signals outside the amateur radio bands. The -3dB points bandwidth of the BPF is sufficient to cover the entire amateur band which you build the kit for. There are example measurements of the BPF response in section 7.7 of the manual.
The current consumption varies with power supply voltage. There is a graph showing my measured values, in section 7.2 of the manual. For example, on receive, the QCX-mini current consumption is 58mA at 12V supply, with display backlight off.
Yes. In Japan the regulations require that amateur radio transceiver CANNOT transmit outside the amateur band allocations. We have a version of the firmware which prevents transmission outside the Japanese band limits. Please email us, providing you order ID, if you require this special Japanese firmware version. The enforced band limits are:
3500000 - 3575000
3599000 - 3612000
3680000 - 3687000
3702000 - 3716000
3745000 - 3770000
3791000 - 3805000
7000000 - 7200000
10100000 - 10150000
14000000 - 14350000
18068000 - 18168000
21000000 - 21450000
24890000 - 24990000
28000000 - 29700000
Yes! All kits always use the latest firmware version available at the date/time of shipping.
If you think you need technical support, the following options are available - in order of preference: I mean, the first one in the list is to be done first! Do NOT start with 3...
- The vast majority of problems or questions are already answered by information in the documentation! The old adage "RTFM" generally applies. Are you sure you read the documentation thoroughly? Check again - also check elsewhere on this FAQ page and on the QCX kit page to see if the information you need is written there.
- Ask on the QRP Labs distribution list https://groups.io/g/QRPLabs. Not a member? You should be! Please join us!
- Study the QCX Troubleshooting page to learn how to debug your QCX
- View the QCX Troubleshooting video to see how to use simple inexpensive test equipment, or the built in test equipment, for debugging
- Email QRP Labs, CLICK HERE for details. We can decide how best to answer your question - by email, telephone, Skype, etc.
Yes! You can choose to order your QCX+ enclosure at the time of ordering; or if you want to order it later you can buy it separately here http://shop.qrp-labs.com/qcxminicase
The main PCB size is 3.62 x 2.25 inches (92.0 x 57.2mm). The 3.5mm jack connectors and BNC connector protrude from the side panels (please refer to the diagrams in the manual).
The display PCB size is 3.62 x 2.34 inches (92.0 x 59.5mm). The controls protrude through holes in the optional enclosure (refer to manual).
The transceiver should work on 6, 10, 12 and 15m bands and kit versions for these bands may be made available in future, once we have had time to test operation and performance on these bands. Generally performance (sensitivity, RF output power, unwanted sideband cancellation) can be expected to decrease with increasing operating band frequency.
From version 1.06, the transceiver could be built for 160m, in which case the synthesizer reference crystal should be substituted with a 12MHz part, not the supplied 27MHz part.
The transceiver as it stands, cannot work LF bands. The reason for this is that the Si5351A Synthesiser chip can only produce a quadrature output (90-degree phase difference) on two of its outputs, down to a minimum frequency of 3.2MHz. Therefore the system can work for 80m (3.5MHz), and 160m (1.8MHz) provided a 12MHz reference crystal is used, but not for LF bands. Modifications would be required to generate the quadrature LO, probably involving a divide-by-4 circuit (e.g. with 74HC74 chip).
There are three circuits in the QCX-mini which have band-dependent components:
- Low Pass Filter (LPF) which is for transmitter output harmonic filtering (inductors L1, L2, L3 and associated capacitors).
- Band Pass Filter (BPF) which filters unwanted signals and prevents them reaching the receiver input mixer (transformer T1, long secondary winding and capacitors).
- Class-E Power Amplifier resonant circuit (L4 and associated capacitor).
The assembly manual provides tables of component values per band, for each of these circuit blocks. Changing the band requires changing all three circuit blocks. In a multi-band QCX-mini you would need to arrange switching between copies of these circuits, one copy per band. It is not impossible. But neither is it trivial... and certainly you will find the very compact mechanical design of QCX-mini to be a significant obstacle.
Please refer to the YouTube video on this topic: https://youtu.be/eN7wER05T-c
All the wire in the kit is AWG-28 (0.3mm diameter) enameled wire. The enamel coating of the wire can be easily burnt away by prolonged soldering iron heat. You can substitute other gauge wire if you wish, it has negligible effect on the electrical properties of the inductors. However, much thinner wire is hard to manage. And thicker wire may not fit easily on the core.
Some people find that the amount of gain available in the receiver is high, and therefore they only ever operate with the lowest 10% of the gain control. This can be changed, see this article.
Yes, this was a case of mistaken identity in the beginning. But it turns out to be a benefit, not a problem. Read more here...
You do not need a PCB for the Low Pass Filter (LPF). The LPF components are installed on the main QCX-mini PCB. Just follow the QCX-mini assembly manual and everything will be fine. The LPF kit bag is the usual QRP Labs LPF kit but with the PCB removed, since it is not necessary. We recycle the PCB into LPF kits for non-QCX+ use.
Please see above. No LPF PCB is needed for assembly of the QCX+ kit. BUT, in some cases for logistical reasons, the LPF kit PCB originally in the LPF kit bag, was not removed. So you have it in your kit bag. You can just ignore this PCB! Throw it away, practice on it, buy another and make it into a pair of earrings... whatever you like!