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Old Jun 01, 2011, 08:53 PM
RC = FUN
Fort Wayne, Indiana
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Does the SAW filter mod actually help out a lot? -Tyler
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Old Jun 01, 2011, 11:05 PM
Fly Chitty Chitty Bang Bang!
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Central California USA
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Originally Posted by flyboy321 View Post
Does the SAW filter mod actually help out a lot? -Tyler
Having to read some saying it was worse.
I use a Hexacon thermotrac soldering pencil. It has a dial and can go up to 850 deg F using 120 watts regulated.
Going to max heat I flowed some solder on top of the old filter. In about 45 seconds the filter started to move. Adding another 15 seconds the pencil was removed and I grabbed two small flat head screwdrivers fast and lifted the old filter off the board angled against the rails evenly. Using solder wick the remaining solder was removed afterwards. I purchased 4 filters 2 were spares. I decided on the second receiver to solder the bottom of the saw to the board using heat just like removal. That was not the right thing to do. Later results showed fuzzy areas on the video link. Don't burn the new saws like the ones that are removed. Heat the work fast, apply solder at the right time. Let cool. I used acetone on tissue to remove the flux. Works well.
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Old Jun 02, 2011, 07:18 AM
Engineer for Christ
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Amherst, VA
Joined Jun 2006
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Originally Posted by flyboy321 View Post
Does the SAW filter mod actually help out a lot? -Tyler
You are highly unlikely to see any difference with the SAW mod. Many of us have done it successfully but have seen little improvement. The reason for this is simple: most people's problems have little to do with RX sensitivity. Problems experienced in the RX side are ususally multipath interference and noise floor. Neither of these problems can be overcome by a more sensitive RX. These problems must be overcome by frequency and antenna selection.

-Alex
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Old Jun 02, 2011, 07:20 AM
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Originally Posted by idletime View Post
Just to be specific...when 'we' say 1.3...is that really 1280 or is it in fact 1300??


thx
1.3GHz = 1245-1296MHz

The cheap multi channel VTX at the beginning of this thread does 1256MHz which gives us an additional 1.3GHz frequency. Unfortunately, I already had one fail on me, so I question the quality. It's also large and heavy.

-Alex
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Old Jun 02, 2011, 09:09 AM
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You're talking about the one from Dino Direct, right, Alex? I had mine fail too, do you have any idea what happened to yours?
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Old Jun 02, 2011, 10:14 AM
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Was it an inflight faliure? (I also have one )
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Old Jun 02, 2011, 11:26 AM
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Originally Posted by pdiddyg40 View Post
You're talking about the one from Dino Direct, right, Alex? I had mine fail too, do you have any idea what happened to yours?
Yep, the same one.

The voltage regulator shorted out internally. I think it was a ua78m05. I'll have to replace it and then check it for heat. As much as I think this transmitter is way too large, there's no doubt that having an extra 1.3GHz channel has it's advantages. I'll have to do some stress testing on this unit too.

-Alex
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Old Jun 02, 2011, 11:28 AM
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Originally Posted by msev View Post
Was it an inflight faliure? (I also have one )
Nope, pre-flight failure. I never flew the transmitter. I'll replace the regulator and see if I can determine the failure cause. It might be over driven. The regulator is speced for 500mA, but with a large heatsink. There is no heatsink on the dino direct transmitter, so the current limit is probably closer to 150mA.

-Alex
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Old Jun 02, 2011, 12:31 PM
NDw
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Ireland, Limerick, Kilmallock
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Originally Posted by IBCrazy View Post
You are highly unlikely to see any difference with the SAW mod. Many of us have done it successfully but have seen little improvement. The reason for this is simple: most people's problems have little to do with RX sensitivity. Problems experienced in the RX side are ususally multipath interference and noise floor. Neither of these problems can be overcome by a more sensitive RX. These problems must be overcome by frequency and antenna selection.

-Alex

Hi do you think the lawmate vrx's are worth the money in comparison the the stock fox rx's?
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Old Jun 02, 2011, 12:48 PM
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Not if you are using a circularly polarized antenna system. I actually prefer the cheaper units If you are using linearly polarized antennas, then the Lawmate is certainly worth the investment.

-Alex
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Old Jun 02, 2011, 01:09 PM
RC = FUN
Fort Wayne, Indiana
Joined Aug 2008
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Alex, what is your favorite, overall video system on 1.2?

I need to buy another combo for my new plane, and might as well get something that's preferred by the pro
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Old Jun 02, 2011, 02:36 PM
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I like the Sunsky-800, personally. It's only 600mW, not 800, but it works down to 7.5V. I use the standard 1.3GHz RX from readymade RC rather than the Lawmate. The cheap RX that comes with the Sunsky is OK with a circular polarized system, but the filtration is kind of poor. I can still do a mile and a half on omnis with the stock RX.

-Alex
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Old Jun 02, 2011, 02:41 PM
NDw
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Is it possible to improve the filtering on the stock sunsky unit?
I know some people have changed the module to the comteach one but I think I read on rc-cam forum you need special tools to set the video lvl afterwards.

And the filtering on the "standard rx" on rmrc site is better than on a standard lawmate?
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Old Jun 03, 2011, 03:29 AM
Fly Chitty Chitty Bang Bang!
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I don't know but possibly at 0 deg K there is nothing flowing unless it is bumped.
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Old Jun 03, 2011, 08:37 AM
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Quote:
Originally Posted by NDw View Post
Is it possible to improve the filtering on the stock sunsky unit?
I know some people have changed the module to the comteach one but I think I read on rc-cam forum you need special tools to set the video lvl afterwards.

And the filtering on the "standard rx" on rmrc site is better than on a standard lawmate?
The filtering on the modules of the Lawmate and RMRC is similar. If you change the SAW filter on the RMRC unit, the filtering will be even better than Lawmate. Lawmate has better video processing, however. The processing in the Lawmate allows it to filter multpathed signals better than a standard RX. With a circular system, the antennas do that for you.

-Alex
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