Dual band performance with multiple adapters

[silverf0x]

I have a dual band antenna on my car that has a 12' coax that doesn't reach me in the drivers seat. I want to use this with my Baufeng UV-5R, and am looking for an economical solution. Will the following setup help, hurt or have no impending effect on my Tx/Rx abilities?

dual band antenna w/ BNC connector
+
BNC to RF adapter (to connect antenna coax to "extension" RF cable)
+
RF cable (to reach my driver's seat)
+
RF to BNC adapter (no RF to SMA adapter at my local Fry's)
+
BNC to SMA adapter (to connect to the radio)

Thoughts and suggestions are welcome. Thanks!

 

[k3td]

Multiple connectors and adapters are multiple points of potential failure, especially if they are not commercial quality like Amphenol, etc. They also introduce loss, and the loss can be considerable if they are not commercial quality.

What kind of mobile antenna are you planning to use, and where/how will it be mounted to the vehicle?

 

[robertmac]

Picket fencing ham repeaters

This set up is just right for picket fencing ham repeaters. 4 or 5 watts out put, degraded by all the connectors. Recipe for turning out a flat cake.

 

[LtDoc]

Connector adaptors/converters are just one way of adding feed line. They usually aren't the 'best' way of doing it, but sometimes it's the only way available. Using them usually means that there will be some loss associated. If that loss isn't enough to make any practical difference, then it's certainly a viable thing to do.
A better way of going about it would be to replace the existing feed line with one that is long enough and has the proper connector(s). 'Better' is seldom the 'easiest' way, right, so what options do you have that fit's that 'better/easier' requirement? Sometimes, those adapters are your only recourse.
Doing away with all the adapters also has another benefit, a mechanical one. I'd say you should be careful how you 'handle' the radio under this sort of circumstance. It isn't unheard of for the combination of all those connectors to cause something to break, you know?
At one time or another, I think everybody has done the 'connector' thingy... (breaking something too).
- 'Doc

 

[silverf0x]

Thanks for all the input, it does help.

The antenna is:
VUM201
Opek
2M/70CM Mini-Mag Mount BNC

Favorable reviews here:
Opek VUM-201 Dual band Mag mount Product Reviews

It's on the roof of my SUV.

 

[silverf0x]

Oh also: I have a 25' cable with BNC connectors. This is my second option even though it's way longer than I need, but has fewer connectors/adapters needed. From the input above, it seems like this would be a better option - yes?

 

[n5ims]

Perhaps you may consider doing something fairly simple. Get a BNC Female to BNC Female adapter and attach it to the antenna's connector (for joining the antenna's BNC to the extension cable). Purchase a jumper cable long enough to go from the end of the antenna's coax to where you need it (RG-58 BNC to BNC should be easy to find). Attach the BNC to SMA adapter to the radio side of the jumper and the other side to the adapter you put on the antenna's coax. You should be good at that point.

Another option, if you're having a custom cable made, is to eliminate all adapters and have them fix you up with a cable that has a female BNC connector on one side and an SMA connector (make sure it's the right one for your radio!!!) on the other. You now have an extension cable that requires no adapters to make it work.

Be aware that the cable on your antenna (that real tiny stuff called RG-174) has very high loss. It was designed for jumpers used inside radios (think 6" as being long for them), not as a radio to antenna coax. The mag mount folks love it since it's very small and flexable, but beyond that it's pretty lossy. A 10 foot run will drop your 5 watt output down to about 3 watts at 450 MHz (and that's if they use the good stuff).

 

[zz0468]

Below 1ghz, even mediocre adapters have less than 0.25 db loss. A longer piece of RG58 could well be lossier than the shorter piece with a couple of extra adapters. That said, a stack of adapters can easily come loose or, worse, break something. Just buy or build a cable of the right length and with the right connectors.o. It.

 

[silverf0x]

Thanks for all the input everyone. I've currently added a 10' RG58 with BNC. Depending on the noticeable loss, I may go back to testing with the extra adapters of my original setup (I did not get a chance to test before changing it out).

 

[N1BHH]

RG-174 cable is lousy and has lots of loss. That antenna is not anywhere near a quality antenna. You'd be lucky to have about a watt reaching the feed point of the antenna with just the cable by itself. If you must use a magnetic mount antenna I would use a Larsen. Their mounts use RG-58 which is a better step above, but the best would be to drill and mount an antenna fed with quality teflex or teflon cable. Low loss is the way to go, as low as is practicable.

 

[silverf0x]

Thanks, I need to be as modular as possible without making any permanent changes to my vehicle. I really wish my local radio shop would have told me about the lack of performance to expect with this antenna. I'll look into antennas with at least an RG-58 cable.