Batboard

I have a Yaesu Vx-5r ham rig (see picture of me to the left.)

Something is wrong with the antenna connector. It will go from full quieting recieve, to nothing, just by bumping the antenna, or moving the radio about. This is just plain unacceptable with a portable radio.

All seemed to be fine and dandy, until the other day, I was on the local repeater. I found out that I was cutting out. The battery was fine, 4 watts of power selected, and I couldn't seem figure out what was wrong. I rechecked the antenna connections, and tighted them up, to see if they were loose.

They could then hear me fine again. I know the problem was in the antenna chain somewhere.

This sort of bothers me, since I don't like the thought of the PA floating between an open circuit and an antenna load. This just isn't the route to make a radio last.

See, the Vx-5r uses an SMA antenna connector. There is nothing wrong with this... since SMA has better specs then BNC does. However, I also have a portable scanner with a BNC connector.

I wanted to share some of the antennas between the scanner and the ham rig. I couldn't find a SMA female to BNC male converter, so I decided to just use an SMA male to BNC female.

I bought Yaesu's p/n "CN-3" BNC to SMA connector. I figured it would be less likely to cause trouble then an aftermarket adapter. (I'm not sure if I was right with this assumption.)

I read around that this is a problem that plagues this model. They mentioned using a SMA tightening tool to fix a loose SMA antenna connector.

I have never heard of such a thing. Where does one buy this tool?

Thank you,

Well i'm not sure whats the problem with yours could it have something to do with the screw that was put in to hold the belt clip on????

I have one of these radio's and it was purchased new in 99 and I have had no problem with it til the other day mine won't receive on 2 Meters but works fine on 440mhz ?????

But I bought a Sma female to BNC male at my local hamfset on thing you want you want to be carefull is the more adapters and stuff the more strain on the connnector ..... But there is a problem with the connector coming loose......

The tip of the sma connector is probably broken loose from the circuit board.

The less you connect/disconnect a SMA antenna the less trouble you'll have in the long run, which is actually a short run. Somewhere, and I think it might have been on the old Batboard, I once read that the SMA connector is designed for only 500 on/off cycles, so if it's true that's the bad news, and there is no good news.

Antenna connectors on ham HT's have been a regular source of trouble for a long, long time. Usually the inside center pin connection comes unsoldered from the board, but the problem actually can take many forms.

If you discover a way to put a BNC in place of the SMA on the VX-5R please let us all know.

Tom, W2NJS
...in D.C.

I guess I will have to open up the radio and check it out.

I really like the idea of the VX-5r sporting a BNC out of the case, rather then SMA. I will have to look into that.

I don't think it was the long screw that I used in the belt clip thread to put a swivel clip onto the radio that is causing this problem. For those of you who don't know about this problem... the screw caused the radio to not power up when it was fully tightened. However, if I loosened the screw just a nudge, the radio would power up okay again. I took out that screw, and the radio worked again. Right now I am running it without ANY screw where the belt clip is. I don't want to put anything into the case, until I know what is under it.

[update]

Argh. I opened it up for the first time, and am now baffled about how to get the board with the pot, rotary vfo, and antenna connector out from the chassis. Any hints?

OK, this not a MOTO, but, I have to admit, I have a VX5 also. I have replaced the sma. I bought a tool that was made out of a 1/4 drive socket. It worked but was crude (gouged the housing). I am having one made that will be better tolerances. Unfortunately, Yaesu put locktite on the threads and not on the space between the housing etc. You will have to take the radio completely apart and resolder the center pin, then you need a good tool to tighten... after putting locktite on the housing area and on the bevel of the lock ring (NOT the threads)....

When the SMA connector works loose in the casting, the casting with a new SMA has to be replaced. They don't cost that much, and you MAY be able to press a new connector into your casting. The most common problem is the contact at the base of the SMA at the contact to the circuit board, kinda a poor setup. Check that contact point, it has a plunger type pin on the board and they get dirty, or just plane flaky.

There are a couple companies out there now making a SMA to BNC adatpter that has a solid body around it taht comes down to contact the case.. atkes teh starin off the SMA, looks good and makes for quicker antenna changes.

Ok, before I comment, I have to say that having an SMA on my radio is both the best thing and the worst thing to happen to my field radio. My FT-50R has been submerged numerous times, been in freezing rain, dropped on concrete, etc, and no problems yet. However, if I'm out of range of the repeater, or I need 440 (my mobile is 2-meter only), etc, and I need to throw on the external antenna, it's a pain in the butt!

There are companies that make SMA to BNC adapters with 6" or 18" of teflon-micro-loss cable between them (to provide a nice strain relief) for about $18-$25. My solution was to rumage through the bins of microwave adapters at the Dayton Hamfest and I found a hand full of them for $5 (and have since given away about half of them, these were 6" to 3' in length). I strongly suggest the Dayton route if you're looking for adapters since I need to have 3 or more of them because I misplace my accessories a lot. (I also own two CN-3 adapters, purchased before I went to Dayton.)

I'm glad to hear of the improvements in the VX-5R over the FT-50R. A few of the other guys in my Search & Rescue unit have had problems with the SMA connector on their radios (FT-50R) and both had to order a new radio frame from the factory (internal frame only, not the radio case). I guess the FT-50R had the jack permenantly mounted to the radio frame and thus a bigger hassel to repair.

Good luck with your repairs and God bless,
Fitz Fitzgerald.
KC8KML

Update:

I finally opened it up today, and figured how to take the little almond colored covers off the flex strips, so I could open it up more.

The SMA assembly is loose from the chassis, and will wiggle back and forth, if I tug on the antenna SMA. The pin from the SMA to the board looks okay, it seems to be soldered in, but it might not be making a good contact. I'm not sure. Sometime soon, I'll get up the nerve to re-solder it, just to be sure.

I really need one of the tools that are used for tightening up the two little dimples on either side of the SMA nut. If you've worked with these, I'm sure you must know what I'm talking about. Does anyone have a source for these?

After that, I'm going to put on one of the SMA-BNC adapters from http://www.wa3hrl.com/smabnc/index.html , and hopefully I won't have to deal with this again.

Then there are TNC's which i think are the best.......I will look into changing mine when i get the experimental VX-150