radio cutting out

[David M. Simolo]

I am going to start a thread with the confession that I don't know much about radio use. I am probably premature with posting this now but it might help me narrow down my search for the problem.

I have a Triumph-LS and a Triumph-2 as a base using the HPT435BT radio. I have both these antennas:

1. UHF Whip Antenna 450-470 MHz, 1/2, 2.5dB, TNC (the one I use most lately)
2. HF Antenna 450-470 M Hz, 5/8, 5 dBd gain, NMO with the ground plane disk

On about 4 occasions now towards the end of the afternoon I have had the radio link to the LS start fading and then disappear over the course of about 5 minutes or less. Sometimes while this is happening the radio will fade in and out but I think typically there are no hertz of communication happening.

This has always been on 35 watt output. The first time it happened was wintery, with no fan running. After the second time, I have been using a fan. I have never observed any components that seemed warm to me although the weather has been generally quite cool yet.

I run this off of a marine deep cycle battery. I forgot to check the voltage this last time but once I checked it and is seemed reasonable (I know this is a weak statement but I don't recall the details).

Yesterday this all happened again. I took the LS back to the base, still no communication. It had been a few minutes since it stopped working but the fan output was not at all warm. I did not reboot anything but I went through the base-rover setup again, successfully. It didn't provide communications and failed immediately with an STN solution. I had a lot of customer distractions at the moment and was on a schedule so I couldn't pay as much attention as I would have liked to the details of what was going on.

At some point I will probably want to add the capability of receiving my corrections over the internet but have not taken that step yet.

As a side note, I have been extremely impressed with this Javad setup. I work in GPS-poor environments a lot and have generally been able to use the LS to get the work done. I have had the occasion recently to get it out into some more open environments and it really screams through the shots.

Any thoughts anyone?

Thanks much in advance, the support here has been great.

Dave.

 

[Adam]

Dave, I have the same setup as you. I use the 1/2 db gain up to 4 watts, this is where you need to switch to the 5 db gain antenna over 4 watts. Which antenna where you using at the time?

 

[David M. Simolo]

I was using the whip antenna, mostly because I have seen Nate indicate that it may work better through brush and woods. Also, I work in 700' vertical relief a lot.

 

[Adam]

Were you using the short antenna or the long one, I was told when I bought my system to not use the 1/2 db gain antenna over 4 watts.
The data sheet shows the power rating to be 20 watts. www.javad.com/downloads/javadgnss/sheets/UHF_Whip_Antenna_2.5dB_TNC_Datasheet.pdf
The 5 db gain has a power rating of 200 watts.www.javad.com/downloads/javadgnss/sheets/UHF_Whip_Antenna_5dB_NMO_Datasheet.pdf
I don't think its a good idea to power more than 4 watts thru the 1/2 db antenna.

 

[David M. Simolo]

I told you I don't know much about radios, thanks Adam. If I knew that before then it got lost in the sauce of the learning curve.

I believe I am using the 10.16" long antenna given my frequency range--I think the specs say its a 1/2 wave 2.5db antenna if I read it right. I am quite certain I have not had this problem even at 20 watts output.

I appreciate the help.

Dave

 

[Adam]

I see which one your talking about, I thought you were using the small rubbery antenna. Dave I don't know what would cause that. So you worked all day and then had the problems in the afternoon?

 

[David M. Simolo]

I just checked the original packaging that the antenna came in: 450-470 MHz 10.16 ” (25.8 cm) p/n 30-050503-02

It does say on the spec sheet that you linked that it is only rated to 20w, I was using 35w.

Yesterday I used it about 4 hours in the morning, then remobilized on a different site an hour or so later, using it for an additional couple of hours. The other times it was after about 6 hours of use.

 

[Shawn Billings]

My first guess would be battery issue. How old is the battery?

 

[David M. Simolo]

It's a Chinese made 35Ah marine battery I bought brand new on Amazon in January. I should probably carry my voltmeter in the field with me, I know Nate would say I should. Then I can keep a better eye on what is going on.

 

[Nate The Surveyor]

This is merely a suggestion. Go to frequency scan, and check for other users. I have been in circumstances where somebody else was walking on my frequency, at a set time every day, for an hr or two. The radios on these things are designed to LOOK and see if anybody else is using the frequency you are on. IF somebody else is on, then the Javad radio won't broadcast. (At least that is supposed to be how they work) So, it checks every second or so, to see if anybody else is on. Try another radio channel.

 

[Nate The Surveyor]

And, I have tried a number of batteries. My last purchase was a Chinese made 50 AH SLA battery. I need if oversized for several reasons. I have the cooling fan. And, I run an electric fence around my base, sometimes, and I HATE running out of power. What you might try is pick up another battery for a backup. And keep it handy. Cheaper than a return visit. I got my bat off ebay. Here is what I got: http://www.ebay.com/itm/12V-50AH-Se...717180?hash=item233711033c:g:Y8UAAOxy0bRTF4LM

 

[David M. Simolo]

I actually have a nice, light gel battery I carry with me and could have used as a plan B for a while but didn't have time nor was I necessarily keyed in on a battery problem at the time.

I will also keep the frequency issue in mind, thanks.

 

[Matt Johnson]

The power supply voltage for the HPT35BT is 9 to 16 volts. If the supplied voltage drops less than 9 volts the radio may still remain on but will not transmit I believe.

 

[David M. Simolo]

I returned to the same site yesterday where I last had the problem.

I throttled the radio back to 20w and had the fan running on a fully charged battery.

I did not initially check the battery voltage but it would probably have been a little spurious having been sitting after a full charge with no load yet.

After 1 hour the battery read 12.65v. After an additional 2.5 hours the battery read 12.55v when I finished up.

There were more fresh leaves in the canopy but I was quite easily able to get all of the shots that started to give me fits the last time as my connectivity was degrading. It was actually quite impressive as I had to reach well past the top of a 150' tall steep bank that was much closer to the base than I would have liked.

This was not as a long a session as other problem times but I thought I'd post these details for now. I will try to keep an eye on things and report anything deemed worthwhile.

Thanks for all of your help and suggestions.

Dave.

 

[Nate The Surveyor]

I like to check my base battery voltage, at the end of my session, with it still broadcasting, and under load.
This should indicate the lowest numbers of the day.

 

[David M. Simolo]

Just to clarify, my readings above were while all was running under full load. Thanks Nate.