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Old Sep 27, 2010, 02:44 AM
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Quote:
Originally Posted by theothercliff View Post
Sunsky went silent on your ongoing problems and you bought from them again?

I am not getting a warm and fuzzy about Sunsky from these failure reports. Is that now 3 or 4 Sunsky FOX-800 transmitters that we know of that have failed this year?

I special ordered two FOX-800's from the manufacturer but have only flown them for a total of maybe 10 flights. They have run fine so far.

Cliff
To be clear, never had either VTx been powered up without an Antenna, but I'm willing to be advised if we are saying that this, or anything else, could cause the unit to drop transmission on all but one channel.

Sunsky attempted to help but didn't agree to a replacement. Going through the process of getting a replacement by sending the originals back was not my choice, especially where I had probably killed any warranty by removing the unit/s from the outer gold heat sink casing.
There were other items that I wanted from Sunsky that I couldn't source elsewhere. Adding just the VTx to my order list made sense.

Judged on efficiency of service, you may be surprised to hear me say that Sunsky are second to none.

Having experienced the service of other FPV equipment suppliers a lot closer to home, I think my expectations may be low.
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Old Sep 27, 2010, 06:54 AM
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Last edited by Mictronics; Jul 01, 2012 at 02:40 PM. Reason: Tired of RCG - Quality can be found at FVLAB
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Old Sep 27, 2010, 08:08 AM
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That graph is from a 1 watt fox tx
Thomas did those tests with one of my fox tx's




Quote:
Originally Posted by Mictronics View Post
Sorry to dig this up again, but I can not agree with what is said about the picture.

The picture tells nothing about a second harmonic @ 2480MHz. With the analyzer settings from the picture a frequency range from 1219MHz to 1260MHz is shown. What you see is the carrier and sub-carrier harmonics.

Here is a picture from a FOX 700mW transmitter:
Attachment 3501356
The 2nd harmonic at 2480Mhz is present but around 3.5dBm instead of the mentioned 23dBm.
An LPF will be fine to suppress the 2nd harmonic at that level. A side effect will be a better reception of the GPS (when used).

I'm running this transmitter with a Mini Circuits 1000MHz LPF. With an Inverted-V antenna I'm getting clear video at 6km range.
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Old Sep 27, 2010, 08:35 AM
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Old Sep 27, 2010, 06:25 PM
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Quote:
Originally Posted by Mictronics View Post
Just want to point out that the picture doesn't proof the description.
Not to mention about a 20dBm difference in power on the harmonic freq thus totally destroying the premise
that adding a LPF could cause a problem.

ian
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Old Sep 27, 2010, 06:44 PM
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I think thoams was more interested in fliters at that time
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Old Sep 28, 2010, 10:06 PM
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Quote:
Originally Posted by dr_patso View Post
yesterday 3.0 miles today 3.5 miles. 1.2Ghz 1W lawmate with antenna assembled by IBCrazy for this frequency+ lawmate receiver and 8dbi patch on channel 8 (1280Mhz)

rock solid video even while banking to come home, so happy with this sytem. not a hint of interference with the ezosd in the nose (vtx on tail) rock solid tlrs receiver in middle with V setup. stock whip and 500mw setting
Patso,

You say you used a 500mw setting. I didn't know that these transmitters had a power setting. Tell me more.
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Old Sep 28, 2010, 10:15 PM
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Originally Posted by cliffkot View Post
Patso,

You say you used a 500mw setting. I didn't know that these transmitters had a power setting. Tell me more.
Read again. He's talking about 500mW power setting on the TLRS control Tx.
It has a 3 way switch on it that lets you go from 500mW to 1W to 2W.
And yes, 1.2/1.3Ghz video Txs have no effect on 433Mhz UHF control systems
which all use low pass or band pass filters.

ian
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Old Sep 29, 2010, 12:57 AM
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You are right, Its my bad.

That photo dose not show any things about the harmonics.
Those picks are the side waves and the first picks shows the Audio TX that is about 5.6Mhz away from the central pick.

I did not notice to the image when share it, I just read the text below but did not notice to the photo very well.

Any how tomas said the first harmonic is 13dB but what we see, the picks are about 23dB.

Thanks for your notice and advice.
Habib

Quote:
Originally Posted by Mictronics View Post
Sorry to dig this up again, but I can not agree with what is said about the picture.
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Old Sep 29, 2010, 01:30 AM
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Quote:
Originally Posted by theothercliff View Post
I don't know you, and for lack of further information, was giving advice for the most probable causes. Don't take any of the following personally.

As you know, NTSC is mixed in the camera, not the transmitter and level is about brightness, not hue. As you know, video transmission systems are just linear amplifiers that should not be messing differentially with phase information (hue).

So, for the camera or display / recorder, Wikipedia (NTSC) says "... color correction can not be performed accurately on the nonlinear (gamma-corrected) signals transmitted, the adjustment can only be approximated, introducing both hue and luminance errors for highly-saturated colors." and your pictures do look highly saturated.

Some cameras don't respond well to really bright sunlight and may saturate the signal. If this is the case you may want to build a simple video attenuator between the camera and transmitter, or if the RF modulation is not bumping its head on the ceiling, between the receiver and recorder.

Some cameras / transmitters / receivers / displays lack proper 75 ohm termination which as you know would increase the signal and saturation.

Heat is another possibility. Is the video transmitter out in the airstream where it can stay cool?

Have you have adjusted the video pot in the transmitter? For others reading this: don't ever adjust the pots in the transmitter. (By the time you have the license and realize that you can adjust the transmitter pots if you have problems, you might understand all the ramifications well enough to avoid doing more harm than good.)

Cliff
Hey, someone that actually understands the details of NTSC video and the RF side of things. Pretty rare in the RCgroups.

OMM
de AF9Y
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Old Sep 29, 2010, 08:29 AM
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Quote:
Originally Posted by Daemon View Post
Read again. He's talking about 500mW power setting on the TLRS control Tx.
It has a 3 way switch on it that lets you go from 500mW to 1W to 2W.
And yes, 1.2/1.3Ghz video Txs have no effect on 433Mhz UHF control systems
which all use low pass or band pass filters.

ian
I don't own any 433 (RC or FPV) equipment but, even with a filter, I would be afraid of the 3rd order harmonics between 433 and 1280. In this case, it sounds like your LRS RC transmitter on 433 would hit your FPV receiver on 1280 / 1320.

Edit: 433 times 3 being 1299 which is too close to 1280 or 1320 for my likes. FYI: odd order harmonics are produced when you over drive your transmitter and get clipping. A square wave is made from all the odd order harmonics with just the right phase and amplitude for each one.

For my own edification, I would be interested in hearing the results of the following experiment from anyone that flies with 433 LRS RC and 1280 / 1320 FPV. It is probably safe as long as your RC doesn't glitch when you turn it off. It is certainly safe if you have a properly adjusted RTH autopilot or perform the test on the ground:
The next time you are at the limit of your FPV video and there is a little bit of video interference, switch off your 433 RC for a second to see if the video clears up. Perhaps switch the 433 LRS RC power setting to a higher level to see if the video interference gets worse.

Cliff
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Last edited by theothercliff; Sep 29, 2010 at 11:33 AM.
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Old Sep 29, 2010, 08:48 AM
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You understand better than most other people about this.

However actual flying tests don't need to be done, ground tests will show you what you would like to know.

Quote:
Originally Posted by theothercliff View Post
I don't own any 433 (RC or FPV) equipment but, even with a filter, I would be afraid of the 3rd order harmonics between 433 and 1280. In this case, it sounds like your LRS RC transmitter on 433 would hit your FPV receiver on 1280 / 1320.

For my own edification, I would be interested in hearing the results of the following experiment from anyone that flies with 433 LRS RC and 1280 / 1320 FPV. It is probably safe as long as your RC doesn't glitch when you turn it off. It is certainly safe if you have a properly adjusted RTH autopilot or perform the test on the ground:
The next time you are at the limit of your FPV video and there is a little bit of video interference, switch off your 433 RC for a second to see if the video clears up. Perhaps switch the 433 LRS RC power setting to a higher level to see if the video interference gets worse.

Cliff
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Old Sep 29, 2010, 11:19 AM
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Quote:
Originally Posted by theothercliff View Post
I don't own any 433 (RC or FPV) equipment but, even with a filter, I would be afraid of the 3rd order harmonics between 433 and 1280. In this case, it sounds like your LRS RC transmitter on 433 would hit your FPV receiver on 1280 / 1320.
I didn't say that 433Mhz Tx didn't have an effect on nearby video Rx gear. It definitely does
and video Rx antennas and UHF Tx antennas need to be positioned appropriately
relative to each other to minimize it.
I said that 1.2/1.3Ghz video doesn't have any effect on 433Mhz Rx onboard the plane.

ian
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Old Sep 29, 2010, 09:59 PM
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Quote:
Originally Posted by Daemon View Post
I said that 1.2/1.3Ghz video doesn't have any effect on 433Mhz Rx onboard the plane.

ian
I think they do have some effect, it would be interesting to see what the uhf rx did next to a 2 watt tx?


Getting the rx away from all emmitting devices is important.
even if your ground tests show you otherwise.
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Old Oct 04, 2010, 02:18 AM
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my 21$ 1.2Ghz yagi is all set up, video looked fine indoors I will range test it this week, for vertical polarization the rods in the yagi should be vertical correct?

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWNX:IT

pigtail
http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWNX:IT
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