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Type: Posts; User: brandon lind

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    The few watt audio signals in a transceiver...

    The few watt audio signals in a transceiver hardly require relays. I havent looked at that radios schematic, but doubt it uses one to switch the audio on or off.

    I would start by plugging in a...
  2. Not sure if anyone noticed but he said he got it...

    Not sure if anyone noticed but he said he got it working.
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    Most fan noise with regard to things in cases...

    Most fan noise with regard to things in cases (like PC power supplies or RF amplifiers) comes from air restriction and cavitation (and can be readily diagnosed with a sheet of paper). It is a fluid...
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    Most fan noise with regard to things in cases...

    Most fan noise with regard to things in cases (like PC power supplies or RF amplifiers comes from air restriction and cavitation. It is a fluid dynamics issue. As for external heat sync fans, either...
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    To the first quoted statement (forgot how to...

    To the first quoted statement (forgot how to separate quotes on here), you are correct. My assumption that it will start with a positive-going signal is completely wrong. Good point.

    Apart from...
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    Got it, no relays. But you could with enough...

    Got it, no relays. But you could with enough delay and a few other things.

    The rise time of the voltage is a function of frequency being what comes out is a sine wave. If you have 20MHz, the...
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    How fast is that oscilloscope? What is it's...

    How fast is that oscilloscope? What is it's bandwidth? You would need to have a dual channel scope, one channel on PTT and another on the RF output to see the actual delay between the two. I'm...
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    I have an SRD, the SDRSmart something or another....

    I have an SRD, the SDRSmart something or another. The fact remains, it cannot handle high power levels on the antenna port.

    Attached is a drawing of how a diode can act as an RF switch for small...
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    Nice setup!

    Nice setup!
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    Update.... Have you done an internet search for...

    Update.... Have you done an internet search for RF Patch Panel? I just did. Seems you are not the first one to have that thought. There is even one on ebay right now.
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    Most transceivers have a diode in the receive...

    Most transceivers have a diode in the receive chain that acts as a switch to shunt the RX path to ground during transmit (thankfully that DC decoupling cap also acts to limit the current). Relays and...
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    Multi-coax switches are common. The patch bay...

    Multi-coax switches are common. The patch bay would be great if you had a variety of radio gear as well as antennas, as most switches do not have enough isolation to keep RF from one transmitter out...
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    Nuts and Volts magazine has a seven part .pdf...

    Nuts and Volts magazine has a seven part .pdf called the Bipolar Transistor Cookbook. It has a bunch of useful circuits including transmitters. Every component is explained and each new section adds...
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    There used to be a user here that was very...

    There used to be a user here that was very opinionated about "walkie talkies" but he is no longer here. Bottom line is simple. If you feel that you got your moneys worth out of it, you got a good...
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    I'd try a different UART driver. I have one...

    I'd try a different UART driver.

    I have one for the usb to uart modules I found online. Maybe that one would work?
    This is the wwindows 10 driver for my uart modules (if the attachment worked)....
  16. With a schematic, one might be able to use a...

    With a schematic, one might be able to use a program like SimSmith or Iowa Hills RFFilter to see if the values are reasonable. I cannot find that schematic.

    Do you have the equipment to test the...
  17. Thread: Clueless!

    by brandon lind
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    We are not there yet over here. Certain agencies...

    We are not there yet over here. Certain agencies and task forces (especially with drugs) use encrypted radios but most sheriff departments do not.

    I'm sure that will change, and when it does, the...
  18. I'm no expert, but I have an opinion. Coax...

    I'm no expert, but I have an opinion. Coax should be as short as possible as VHF and higher frequencies see loss in every foot of extra cable (as do all frequencies, but the loss is worse at higher...
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    Most emergency sercives have gone digital,...

    Most emergency sercives have gone digital, particularly P25 by Motorola. With regards to emergency frequencies of the analog type, such as interstate interoperability and disaster go to frequencies,...
  20. yea that was my crash course in emissivity. lol

    yea that was my crash course in emissivity. lol
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    Homebrewing is a great option for linear supplies...

    Homebrewing is a great option for linear supplies if you have the money and the time. I personally like the 2N3055's. If you order extra, those make great audio amplifiers too!
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    Both of us started with a spring but took them...

    Both of us started with a spring but took them off. These antennas are so heavy that they get to swinging around a ridiculous amount using the springs that came with them. I am sure there are...
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    Update: I know this thread is old but I finally...

    Update: I know this thread is old but I finally found the original source code for this on a failing hard drive I had tossed in a drawer. The entire visual studio project folder is here for the...
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    Thanks for the reply. If it was in response to my...

    Thanks for the reply. If it was in response to my former question, the antenna is already installed. It is 102" mounted on a piece of flat stock designed to attach between the roof rack rails of a...
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    I don't know much at all about this but I've...

    I don't know much at all about this but I've tried something similar myself with no luck. The first answer on this link is the reason I have come to accept.
    ...
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