swake

Module Comtech alone?

7 posts in this topic

Posted (edited)

Hello, I have a Comtech FM2400RTIM8 and I would like to know if it is possible to use alone so without the electronic part shipped with?
Is it possible to block it on a single channel (example 2510) without using pins number 14 and 15?
I do not need several frequencies but just one.

Thanks

(Bonjour, j'ai un Comtech FM2400RTIM8 et je voudrais savoir si il est possible de l'utiliser seul donc sans la partie electronique livré avec?
Est il possible de le bloqué sur un seul canal (exemple 2510) sans utiliser les broches numero 14 et 15?
Je n'est pas besoin de plusieurs fréquences mais juste une seul.

Merci)

 

Lawmate 2.4.jpg

Edited by swake

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Sorry, but the attached PC Board is needed. It does two major things:

(1) The board's microcontroller sends a serial data message (~32-bits) to the Comtech module that configures it to the desired channel frequency.

(2) The Comtech's RF signal output is a raw baseband signal. This signal needs to be further processed before it can drive the composite video display. The attached board does the required magic.

 

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Ok I now understand better.

Thanks

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Posted (edited)

I placed a resistance in parallel to the output to have 75 ohm.

710569IMG2167.jpg

Is it with this protentiometer that we set the video level?

325377IMG2166.jpg

Edited by swake

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You are making a mistake. Do not put a resistor on the output of the vRx to reduce the measured resistance to 75 ohms.  A video output circuit is designed to drive a 75 ohm terminated monitor. Your added resistor will disturb this circuitry by "double terminating" it.

I think you are confusing this issue with Lawmate's poor design found on some of their vTxs' video inputs. But this issue has nothing to do with their vRxs'.

 

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I don't have that vRx to measure.

In a traditional design the video output would be AC coupled using a large value series capacitor, so  measured resistance would be infinite. But some newer vRx designs have an alternate video drive circuit that eliminated this big cap to save space, so some measured resistance is possible.

Your meter is warning you to change the battery. Be aware that readings may be inaccurate if the battery is low.

Your link is for SAW filter replacement. It was also discussed on this forum many hears ago:
https://www.rc-cam.com/forum/index.php?/topic/3276-wireless-av-receiver-saw-filters-whats-this-all-about/#comment-23168

 

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