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Old Jul 05, 2014, 10:46 AM
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Joined Mar 2012
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Low Range Problem

I just put together my first FPV system. Im using the new HKQuanum DIY FPV Goggle Set with Monitor (KIT) and the Boscam 5.8Ghz 200mw FPV Wireless AV Tx & Rx Set . To test it I went to the field with my spotter ,as I flew my spotter tested the video sys. and enjoyed the ride the problem is I tried to use it on day 2, and no range? maybe 50 ft. no change to the sys,same channel,same batteries,(tested).
I've cycled the channels,changed all the cables, Tested the sys with the stock monopole antenna, changed the monitor, changed the batteries, I did find a broken Video lead in the headset monitor .This may be the key. the first problem I had at the field was no video signal. so I went home, powered up the system and swapped out the video cable, by mistake I swapped the video and audio cables. Video came back by using the audio in, on the monitor? I put everything back together and went to the field to fly. this is where I ranged checked the video sys and was shocked by the loss of range. maybe I damaged the receiver swapping cables? any thoughts. Also, Im not an RC newbie only FPV newbie. many years building, flying, teaching and selling RC but I stopped for 15yrs and jumped back in a couple years ago. loving most of my new gear and really want to fly FPV.
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Old Jul 05, 2014, 10:50 AM
Hex Heads, Hex Heads!!!
United States, IL
Joined Oct 2011
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Have you ever powered up your video transmitter wuthout the antenna on? Doing so would fry it, wich MAY account for your lack of range.
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Old Jul 05, 2014, 03:57 PM
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Originally Posted by rtbreeder View Post
Have you ever powered up your video transmitter wuthout the antenna on? Doing so would fry it, wich MAY account for your lack of range.
Going a bit off topic, but I once had the video tx antenna break off during a hard landing, took a minute or so before I got to the plane and disconnected the power, though there's no difference in performance now (that I can tell), is damage usually instant?

OP: is range fine at close range and degrades very quickly beyond a certain point?
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Old Jul 05, 2014, 04:54 PM
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United States, GA, Kennesaw
Joined May 2011
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Quote:
Originally Posted by timbits View Post
...... Video came back by using the audio in, on the monitor? I put everything back together and went to the field to fly.
.
This is the key troubleshooting step.....you should not just "get video" on the audio line... it appears you have broken ground connection. (aka 'floating A/V ground')

This would account for both the poor performance and 'video' on an audio line.
(I suspect it is incorrect video signal even if somewhat viewable)

Check cable continuity.
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Old Jul 05, 2014, 07:36 PM
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Originally Posted by cantremember View Post
Going a bit off topic, but I once had the video tx antenna break off during a hard landing, took a minute or so before I got to the plane and disconnected the power, though there's no difference in performance now (that I can tell), is damage usually instant?

....?
Higher wattage Tx (1w, 2w, 5w amps) would fry, but stuffs like 25mW do not have a whole lot of energy reflected back. Semiconductor junctions in MESFETs or MOSFETs get to absorb the energy, so it depends on the size of the junction and the resulting energy density.

Instant, yes. But how much energy, is also key.
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Old Jul 06, 2014, 02:18 PM
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I've cycled the channels,changed all the cables, Tested the sys with the stock monopole antenna, changed the monitor, changed the batteries, I did find a broken Video lead in the headset monitor .This may be the key. the first problem I had at the field was no video signal. so I went home, powered up the system and swapped out the video cable, by mistake I swapped the video and audio cables. Video came back by using the audio in, on the monitor? I put everything back together and went to the field to fly. this is where I ranged checked the video sys and was shocked by the loss of range. maybe I damaged the receiver swapping cables? any thoughts. Also, Im not an RC newbie only FPV newbie. many years building, flying, teaching and selling RC but I stopped for 15yrs and jumped back in a couple years ago. loving most of my new gear and really want to fly FPV.
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Old Jul 06, 2014, 02:20 PM
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here are some pics of what I found when I opened the lcd monitor.
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Old Jul 06, 2014, 02:44 PM
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At no time did I knowingly power up the TX or RX without an antenna, but I did adjust the TX antenna. does anyone know where I can find a resistor value for these antenna or the proper way to check them.I wouldn't want to install a damaged antena on a new TX if its damaged.
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Old Jul 06, 2014, 04:16 PM
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Here are some pic's of my set up It worked perfectly until the monitor cable failed.
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Last edited by timbits; Jul 09, 2014 at 10:58 AM.
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Old Jul 08, 2014, 11:46 AM
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I posted pics here of the monitor cable problem I found. To be clear,I patched video out from the RX into audio in on the monitor headset (at the time I had no picture if I patched into video in regardless of the source I used) I did this before I found the broken cable Knowing this meant sum thing was wrong with the monitor I investigated further. It seems the audio and video share a common ground on the monitor this may explain the floating video. But after the fix I had no effect on the receivers range.
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Old Jul 08, 2014, 06:41 PM
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Get a TX RX system that has RSSI.

That RSSI will tell you plenty!
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