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Thursday, 3 January 2019

The successful testing of my TTI TCB-550, concluding my CB tests

As another radio that had stood idle for some time, though it did power on when I did the CB/Amateur differences video, was my TTI TCB-550, so it was reunited with its microphone which was connected to the computer interface, and connected it to a speaker, as it had the speaker removed, and the mic to run it as normal as with it being a CB the audio turns off should the mic (or properly wired PC interface) be removed.

The radio receives and transmits fine, only indication of receive is "RX" on the screen (the TCB-565 which uses the same fundamental electronics has an S-meter on the front), the TX indication is simply "TX" on the screen, the radio's finals are operating as they ought to be putting out the 4 watts legal power.

This radio was used for my rarely active and since closed 27MHz FRN gateway, the antenna was the excalibur antenna with SWR at unusable levels (though I had and still have a matcher), this is why the speaker was removed and a semi-permanent operating fan was fitted though I have since took the fan off, I plan to use this radio for range tests on stealth CB antennas from the home QTH, as these antennas are to be stealth I of course won't be saying where they will be mounted, of course they will be temporarily mounted and removable in less than 10 minutes, all antennas I use will be temporarily mounted.

To make this run as an antenna range testing radio, it needs interfacing to a PC, the interface I used for it originally had been repurposed for use with the likes of my Leixen VV-898, thus meaning I'd need to build a simple interface, should be able to get away with a simple circuit and an automotive relay so that TX and RX are properly controlled, a Raspberry Pi to run the test transmissions, the radio to generate the RF on any available CB channel, and I want to set it up to transmit the test transmissions every few minutes but not constant carrier RF as this, even at 4 watts, may warm them up and shorten the life of them.

I did a little test of my desk mic as the plug has been changed back to a Uniden pinout 4-way which the TCB-550 has, the audio levels in it are poor, the gain pot is in dire need of replacement and the tone pot is not a million miles behind it, so a complete refurb sounds good for it, the TCB-550's mic will be returned to the computer interface in due course.

The test set (dummy load and Zetagi SWR/power meter) will remain in situ until the arrival and complete test of the Team RoadCom-FS and the linear it supposedly comes with (though the linear will be subject to further tests to find out if it is clean or not, and as it only operates 26-30 MHz the input radio has to be in that range), I have done a brief compare of how my Midland 42 truly performs on batteries over its car kit, the car kit does allow the radio to run the full 4 watts, the power is no more than 2 watts on the batteries, and I did do a video showing just how dire, over a short distance, handheld CB radios actually are between one another, the contributing factors being voltage drop on the batteries and exceptionally inefficient antennas (a 1/4 wave is 2.75m long or thereabouts and an antenna that long on a handheld radio is not ideal or practical), the car kit was connected to my 7A supply using a cigarette lighter socket which I had fitted ring terminals to, rather than mess about removing the plug, which I had somewhat water sealed for my planned but otherwise not started scooter CB project.

The only niggle the TCB-550 appears to have is a slightly crackly volume control pot but it's otherwise ok.


73 de 2E0EIJ/26CT730

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