I am working on putting together a Kraken Mobile DF for VHF (121.5-243MHz) and UHF (380-512MHz).
The plan is to have 2 arrays drilled into roof. VHF at the front and UHF at the rear. They would be switched via 12V relays either manually or via Kraken software.
Since the radius of the UCA is set in the admin section, this is problematic to adjust in the field.
Is there a way to update the user app to allow for macros or channels that automatically adjust the antenna spacing in software and switch the relays accordingly?
I built a switch (array) for a similar purpose (vhf&uhf vs. 750&up) using inexpensive sma rf pcb switches with 5v control found on amazom. The prototype seemed to work fine but never came up with a good way to package them for mobile use. Control is done with a local switch or remotely with a pi zero 2w and a simple web page (like the many control-an-led examples) over wifi. I also use it to turn the ksdr and doa pi on/off.
I am using 5 of the Ducommun technologies model 2SE1T11JB.
They are 12VDC, 250ma and good up to 26Ghz. These have a failsafe of position 2 when not energized.
Plan is to mount the whole set to a 9x20" piece of plywood and install in the cargo compartment behind the rear 3rd row seat in a Ford Expedition.
I have been testing the Kraken mobile with great success. After measuring what seemed like 16 times, before drilling, the VHF array is working well within expected specs.
I do have a question about overload from LMR radios in the vehicle. The VHF APX radio will cause the kraken board to lock up when running 50 watts. But, not when running low power at 15 watts.
UCA is at the front and VHF LMR antennas are mounted aft at the very back of the roofline.
Is there a trick to help the kracken put up with this scenario?
I have some inline 10DB attenuators on order as a first thought…
First, be very careful when broadcasting near the Kraken, it’s not designed to have something broadcasting right next to it, and that could destroy the board. The max input power allowed is +10dBm.
If you want to run a TX next to the Kraken you’ll need to look at some sort of switching mechanism, that can be used to disconnect or ground the antennas during a transmission.
If you add attenuators, then you’re reducing the Kraken’s ability to detect weaker signals.
Here is my solution to deal wirh 2 mobile arrays and tx attenuator. Thanks Carl for your suggestion. I pulled the PTT off the control head mic jacks to engage the disconnect relays.
Here are my suggestions for future upgrades to the Kraken board functionality.
Add a PTT input to the board that disconnects antennas (simulate tx attenuator). This may be easy as it’s my impression that the kraken does this when calibration is enabled. Mobile DF folks really need this for SAR operations. Fixed stations with LMR transmitters could benefit as well.
Incorporate four latched relay outputs to drive relays (selectable as momentary, digital and pulse delayed) to select multiple arrays. Modify software that drives these to be user selectable based on array freq ranges.
One could also output digital info to control an outboard multi-array switch board (made for kraken) to allow full range DF mobile or fixed.
Perhaps we can update software to allow the Orange pi-5b to drive the relays and input tx attenuator functions in the mean time.
As I am not a coder (more of a hardware guy) I can really only help with user functionality suggestions.
Thanks for this great product. I am having a lot of fun with the Kraken.
