Mobile antenna mount problem solved!

[dbvanhorn]

I’d like to do a write up on this for the group. In short, I gave up on the whole template etc idea because it’s a bit clunky and time consuming, and my roof has ripples which make a lot of antenna positions untenable.

What I did was to decouple the two problems. 1: I need the antennas mounted in positions that work for the Kraken at the frequency of interest. 2: I need the antennas mounted where there’s sufficient flat space for the antennas. 3: (no-one expects the spanish inquisition!) I need whatever I come up with to be easy to deploy and stow.

So here’s what I did, the short version: Start with the Arrow Kraken antenna mount, but don’t use any of their antennas. Leave off all the parts for mounting to the mast. You’re left with two circular plates, and five arms, and ancillary hardware. Take an existing set of five antennas for the Kraken which have interchangable antenna elements on mag mount bases.

Some hardware later (which I will explain in full writeup) I have a folding array that mounts SECURELY to the car, and can be deployed or stowed in less than a minute.

Not quite final version shown in pic:

[ke7mqf]

I too have the arrow mount (and antennas). I am very curious how you plan to “fold” the arms.

[dbvanhorn]

The front boom (#1) does not fold. Two bolts.
Booms #2 and #5 fold, they get one bolt in the outer position, and a linch pin in the inner position. Pull the pins and fold.
Booms #3 and #4 have to be removed and laid aside #2 and #3. They get two linch pins.
In the picture, boom #1 is off to the left, and #5 is coming at the camera.

[dbvanhorn]

The center bit is the NMO mount, NMO to N adapter and barrel, sticking up through the plate. When ready to roll, I put an N bulkhead connector on top, which won’t pass through the hole, and so the array can’t come off without all that unscrewing or ripping a hole in the roof.

[ke7mqf]

Nice. I’ll have to give it a try. Thanks.

[dbvanhorn]

Deployment. Here’s the system out of the bag. The Kraken, Pi, Powerbank and extension SMA cables are sitting in the back seat along with the tripod bag:

Next, I remove the linch pins holding booms 3 and 4 in their temporary position. Booms 2 and 5 have a nut and bolt holding them in position with their inner holes, allowing 3 and 4 to use the holes normally used for 2 and 4 outer, while the array is folded.

So having pulled those linch pins I can now set booms 3 and 4 aside, fold 2 and 5 into position and insert those two linch pins which puts booms 2 and 5 in position and ready to go.

Now I pull the four linch pins stored in the 3 and 4 positions, slide those booms into position and re-insert the linch pins. The array is now complete and ready to put on the car.

I already had an NMO mount in the perfect spot, plus I don’t want to transmit near the array anyway, so I have an NMO to N adapter and N Barrel on the NMO mount. The NMO barrel fits through the center hole on the array with a little slop, but it will certainly keep the array from flying off! I just add an NMO bulkhead connector which will NOT fit through the hole in the center plates, and the array is now locked down.

Now a quick walkaround to put each boom in ideal position (there is a little slop) and attach the antennas of choice.

…

With antennas on, then I connect the array cables to my SMA extender snake (five SMA M-F cables in loom) and connect that to the Kraken, passing the extension cable through the van window which is already rolled down.

The “legs” on each boom are a small rubber coated magnet with M6 stud, an M6 coupling nut, a pair of M6 nuts above and below the boom, and an M6 bolt of suitable length. The nuts are intended to allow the booms to be adjusted to be flat across the array, but so far “all the way up” seems to be the right position. If I find different later, then I will adjust them and loctite them in place. The magnet, Coupling nut, and the bolt are held with Loctite Blue so I don’t have to worry about them getting loose without my direct action.

In the tripod bag is also a small bag with alternate antennas, spare hardware, spare linch pins, and a pair of small crescent wrenches.