Switching BPF/HPF, PTT, bypass, sequencer

Hi friends radio amateurs!

Recently I received my mini-lime. Now I am deeply studying the topics of the forums. Thanks to reading, I managed to solve all the problems with my lime mini and was able to launch this board for reception and transmission.

I want to thank Eduardo separately for the SDRangel program!
(I scolded the author at the beginning of my journey, because at first glance it was very difficult to manage the program after simple and intuitive control pattern in PowerSDR from Flexradio and SDRSharp. Slowly I mastered SDRangel and understood the genius of the approach of Eduardo to writing a great program!)
I also want to thank Marty and Brandon for Eduardo’s support, as well as in consultations on topics of the forum for novice users of Lime and Mini-Lime transceivers. You are doing something important!

Now I would like to raise a few important questions that I did not find at the forums or whether these issues were scattered or did not have a solution for today.

  1. Use boar Lime/Mini-Lime for the needs of amateur broadband radio monitoring. To ensure maximum technical parameters, it is necessary to use bandpass filters at the input. I have the experience and the ability to develop filters. And I would like to know if there is a possibility of a software connection or selection of several filters in the future for a separately specified range of freq. (BPF for HF/27/50/145/222/350/430/900/1290/etc, Notch filter for 88-108/433/446/900/1800, etc.)
  2. As mentioned earlier in various forums, many of those who are interested in Lime / Mini-Lime can not fully use the card as a broadband QRP (or non-QRP) transceiver, since it is not possible to simply switch the reception / transmission (external PTT / tangenta key) , bypass, sequencer. Just like the lack of switching BPF.

Without the possibility of switching, the Lime/Mini-Lime board remain “flawed/restricted” toys for pampering in their spare time. Or simple arrangements with very limited functionality.

I welcome any thoughts and suggestions for implementation.

ps: I’m not a programmer, and I see no difficulty in creating software. I’m a simple Windows user and Linux.
But I see limitations in terms of RF design and final functionality.

Is there anyone here who could / would be interesting to implement the software functionality of switching BPF/HPF, PTT, bypass, sequencer?

pps: The hour of the sattelite Es’hali launch is coming to. The Lime/Mini -Lime transceiver is one of the few that you could use to transfer to 2.4GHz. For normal operation, it requires a ppt, bypass and amplifier.

In the next stream our colleague Mr. Pauluzs presented his block diagram of an all-band transceiver based on mixers.

I supplemented the scheme a little, redrawed it and I propose a method of implementation. The structural scheme is not very complete. This is only the first draft.

Any your thoughts, ideas, wishes are welcome!

1 Like

Great start, could you switch the ADC IN/OUT with BPF IF RX/TX on the 1st and 2nd PE4259? this way there is one less switch between the ADC IN/OUT if one wants a Bypass for other uses.

Mr. Pauluzs, I correctly understood your idea?

Simple reversible circuit only for HF range. Up to 10 or up to 30 MHz to select and try.

Now there are no problems with performing any of the blocks shown.
There is only one restriction! It is the main problem!
There are no control signals for external devices supported by the program. BPF/LPF, ATT, LNA, etc.

The minimum of functional signals is absent.
Suppose that most control signals are missing for first step. BPF and LPF in simple mode we can be switched manually. BUT! We can not give a PTT signal to the mini-lime card, which would tell the program about the beginning of the transmission mode. And we can not get a signal from the mini-lime board to start correctly switching the receiving and transmitting equipment with the specified time parameters.

This problem worries me the most now and stops me from doing a project in hardware. Unfortunately, I’m not a programmer and I do not know the magic of writing my own or correcting other people’s programs. Therefore, I have to ask the forum to do this.
For my personal needs of broadband monitoring, I will without any problems do myself manual control of BPF and LNA. But, you see, if all the hardware could be correctly managed from the program, it would be very cool !.

Hi Alex,

About the switch:
Yes almost just put one more PE4259 before that with the second output straight into a sma.
(see the first switch in my last drawing)

The lack of driver support shouldn’t stop you, i’ll be willing to put effort into probably some arduino code that can speak I2C with the host pc and figure out a way to interface to it in gnu-radio if needed. Although this would be a work around for direct interface to the Lime, what indeed would be very cool to have.

Could you tell me some more how you want to monitor and filter? Use a low sample rate and filter just one band, Or sample the whole 30.72 HF spectrum at once and use one LPF?

The PTT input signal can be given at the computer, we need it for processing anyways. One could i.e. do remote PTT if desired, i use my space-bar as PTT in some flowgraphs.

I;m using the PA board from a Yasey FT-857. It has most of the features you are showing. I just need to interface it with the Arduino section of my Udoo X86 Ultra miniPC. Also need to copy the blown driver amp from the RF board. It will work perfect.
I got the radio (No faceplate) with a known driver MOSFET on Ebay for $125, The PA section all works fine.
PA has TX/RX IN for the Lime. BPFs, LPFS, TX/RX switching, Atenuator & the such. PA board outputs to 2 SO-239s. HF-6 Meters/2 Meters & 70 CM. Great way to go, if you can find a “Shack in the box” PA & filtering sections.
This will be installed in a 12" touchscreen mobile computer from the WIN XP days. A mobile/portable unit.


I’m sorry, the preface dissapeared.
I went this route. SMA relays, Kenwood TS-440 PA/BPFs/LPFs/TXRX,
THen came 2M & 70CM. 60W PA modules that can be biased AB, BPFs, LPFs, more SMA relays,…
Well, next thing you know, I am triple of my area provided.
Found the FT-857 chassis & now have loads of space. In fact, there will be 2 other RTL dongles inside, along with 1-128db attenuator & a few other things.

Once all done, I would like to have a full on ham radio, VNA, scope, Spectrum analyzer, etc…


Hello Paulus.

The answer about the filters:
In this issue, a big topic for discussion is possible.
I’ll start from the ADC chip parameter - it’s 12 bits. This figure is, as we say “stumbling block”, which determines the dynamic characteristic of the receiving tract for blocking. Another important parameter that I can not take into account is the antennas that stand above your radio-shack. Small magnetic loop antennas and mini-vipe type antennas give small useful signals, but little interference. Large antennas such as a dipole or full-sized frame at 40-80m give great useful signals, but also a lot of strong interference that can cause ADC overload.
How to choose the right type of preselector for different situations?

I propose the use of narrow band filters for each amateur band. This solution effectively eliminates interference, but it is difficult to make and configure. There is another restriction - you will not be able to watch the broadcasting sections of frequencies and other interesting freq’s.
You can use semi-octave or quarter-octave filters. Their design is simple, but effectively filters such filters only in the far zone in frequency. In the near zone of frequencies such filters do not work, but you can listen to broadcast stations. For example, China International Radio or All India Radio. LOL :smiley:
With a weak dynamics of a 12-bit ADC, it is difficult to find a balance. You must look at our own capabilities and the antennas used. And also, on the level of interference(QRM) in your QTH

For starters, we can apply quarter-octave filters, as simple in manufacturing, and then, let’s look at the state …

Question. Are you looking to go all out, or a decent amateur radio, with general coverage HF receive. Download the Kenwood TS-440 service manual & go to “Band decoding”. Simple 4 bit BCD signal gives you 10 bandpass filters from 30 khz to 30 Mhz. Also, your HF PA & LPFs.
Just a bit of dremel work.
I have used the system together at one point, with a Rube Goldberg kinda setup. Worked nice.


Hi Alex and Ed,

Like the modular approach Ed described as well, albeit that i find the rig-in-a-box is still pretty large. Because there indeed are several ways to filter switch and amplify, it would be nice if parts could be changed to the users preferences. I’ve seen some PA/BPFs/LPFs/TXRX modules pre-made still they are bulky for the max <10dB the lime will put out.

What i don’t like about the SBC setup (udoo, rpi etc) is that it’s not interchangeable to a normal PC/Laptop/ tablet with usb only for switching. This could still be done with an arduino or straight off the lime, which would only use usb and still be compatible with SBC’s

@Alex_RK6AJE Some questions about the parts you use in your drawing, the RA30H series seems obsolete at normal chip retailers. next the PE4259 is rated for 10Mhz-3Ghz, Does this mean 160-40 meters is already outside this range, and at the top its 3Ghz compered with the 3.8 for the Lime.

Gave a quick go at a com/switch/interface board, based on the HMC241AQS16(E) DC-3.5Ghz still not 3.8 and a bit more expensive with better figures. It also has Clock distribution, GPIO’s, I2C and FAN pins for V1.0 to V1.2 Mini’s. By changing the SMA connectors around the board edges to 90 degrees angled ones, it’s possible to connect filters, upconverters switches etc at the sides and rear instead off straight up.

Suggestions are welcome

Hello Pauluzs!
Not all components available to those present at the forum are available in our country.
I offer PE4259 so far that only as an option, for clarity idea.
Chips PE4259 it turns out to buy cheaply and quickly from Ali or Ebay. Also, these chips have successfully used Flex Radio in their HF transceivers. Several designs from our local radio amateurs show their excellent work on HF. Do not worry about the quality of their work below 10MHz.

After your words, I have now rethought the whole concept.
It is not necessary to do on the principle of “all in one”. This is very difficult to implement.
Perhaps the right solution is to make modular consoles on different frequency bands:

  1. A separate module connected to Lima on the HF section - 0.1 … 70 MHz.
  2. A separate module, connected to Lima on the VHF/UHF section - 144 … 1300MHz. (144/222/430/1300)
  3. A separate module connected to Lima for the most advanced microwave fanats - for frequencies above 2 GHz.

All modules have different implementations for parts designed directly for a given frequency range.

How do you look at the idea?

About amplifiers of a series РА30.
Please, keep in mind that you have in your stores, a newer parts. We do not have that.
PA30 is also an example. We have them available “a lot and cheap”, as they are available for many on Ali. You can apply PA60 and PA80. See what’s available in your stores.
Share your ideas too? What is new in you markets for VHF/UHF PA?

I want to focus on the important moment!
If we consider the construction scheme of the type “for all radio amateurs in the world” - it is very difficult to take into account the available assortment. And the US has one assortment, another in Europe, another in China, another in Australia. Therefore, I now focus not on a specific scheme, but on common modules, according to which everyone can choose what is convenient for him and can be bought in his country.
I can do hardware from what is available to me, you do - from what is available to you. Sharing information and experience in this forum, we can make each other rich in ideas. And also, to show people that everything is possible!

Do you like this idea?

For example, I had the idea of ​​THIS TOPIC after I saw YOUR topic-question about 40MHz clocks.