High swr on firestick

[wpwx694]

Getting high swr with firestick, what can I do?
Would moving the antenna side of the bed where it's not behind the cab or putting it at the tail gate?
Thanks

 

[prcguy]

What is the SWR on ch1 and ch40? Is the mount assembled correctly? Is the mount grounded to the inner bed wall? I've had very good success with CB/HF antennas in the same area so it can work.

 

[nokones]

What are the VSWRs. Also, a close up of the antenna mount would help too.

 

[Backwoods40]

I had the same problem last year and spent a lot of time troubleshooting placement, coax, radio, meter, etc.
The third coax I tried fixed the problem. The first two were "quality name brand" cables, and the third was this one:

https://www.amazon.com/dp/B001JT58OY

Not sure why the other cables gave me bad readings on the mobile, because they work fine POTA.

 

[nokones]

I had the same problem last year and spent a lot of time troubleshooting placement, coax, radio, meter, etc.
The third coax I tried fixed the problem. The first two were "quality name brand" cables, and the third was this one:

https://www.amazon.com/dp/B001JT58OY

Not sure why the other cables gave me bad readings on the mobile, because they work fine POTA.

What were these quality name brands and where did you purchase them from?

 

[K6GBW]

Can't tell from the picture if there is a bed liner on there or not. I'm betting the mount isn't properly grounded to the bed. If it is then it's likely it just needs to be tuned. Is this a Firestik II with a tunable tip? If not, then likely some cutting will be involved.

 

[prcguy]

I had the same problem last year and spent a lot of time troubleshooting placement, coax, radio, meter, etc.
The third coax I tried fixed the problem. The first two were "quality name brand" cables, and the third was this one:

https://www.amazon.com/dp/B001JT58OY

Not sure why the other cables gave me bad readings on the mobile, because they work fine POTA.

I suspect it’s the length of the cable and not the “quality”. If the ground plane is lacking then RF currents will flow on the coax shield as it becomes the major counterpoise for the antenna. An 18ft long or 1/2 wave of coax will not work well as a counterpoise but about 9ft will so you might see if the various coax lengths are way different.

 

[Backwoods40]

I suspect it’s the length of the cable and not the “quality”. If the ground plane is lacking then RF currents will flow on the coax shield as it becomes the major counterpoise for the antenna. An 18ft long or 1/2 wave of coax will not work well as a counterpoise but about 9ft will so you might see if the various coax lengths are way different.

That was my line of thinking.
Different length coax can affect swr.
I'm sure every scenario could be different, I just wanted to add one possible solution.

There are some very helpful and knowledgeable people on this forum, and I'm grateful for you guys.
There are also some that seem to enjoy having a lot to say and wisdom has been chasing them a long time, but they've always seemed to outrun it.

 

[prcguy]

That was my line of thinking.
Different length coax can affect swr.
I'm sure every scenario could be different, I just wanted to add one possible solution.

There are some very helpful and knowledgeable people on this forum, and I'm grateful for you guys.
There are also some that seem to enjoy having a lot to say and wisdom has been chasing them a long time, but they've always seemed to outrun it.

In a good install with adequate ground plane it should not matter what coax length you use and it should not change the VSWR.

 

[slowmover]

I had the same problem last year and spent a lot of time troubleshooting placement, coax, radio, meter, etc.
The third coax I tried fixed the problem. The first two were "quality name brand" cables, and the third was this one:

https://www.amazon.com/dp/B001JT58OY

Not sure why the other cables gave me bad readings on the mobile, because they work fine POTA.

Quality would be in buying jumpers from DX Engineering, Ham Radio Outlet or a distributor of Messi & Paolini. There are smaller houses well-trusted so I’d research opinions.

Mobile takes very little length so that — price-wise — there’s zero reason to go cheap.

Truckstop coax (your choice shown) is hit & miss. Mainly, the connectors aren’t very good. But it’ll be an okay source of ground braid.

LMR-240 Ultraflex ought to be the reference; with genuine AMPHENOL ends. If you plan to run some FT240-61 toroids as chokes at both ends then consider RG316 as it has an appropriate bend radius.

6.3’ or 19.7’ coax length won’t matter. What will is a well-protected coax run (flame-resistant split loom) and properly-secured every so many feet (Adel clamps) and out-of-the-way of all else (vehicle electrical).

.

 

[slowmover]

Can't tell from the picture if there is a bed liner on there or not. I'm betting the mount isn't properly grounded to the bed. If it is then it's likely it just needs to be tuned. Is this a Firestik II with a tunable tip? If not, then likely some cutting will be involved.

That’s my guess, as well. Luckily, it’s also an antenna of decent length.

Watched one of my neighbors recently go past with a 2’ antenna stapled to the side of a pickup bed toolbox.

.

 

[EAFrizzle]

Watched one of my neighbors recently go past with a 2’ antenna stapled to the side of a pickup bed toolbox.

.

10 over 9 at the corner of the block, good buddy!