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KD8LWX · #1 09-11-2009, 01:32 PM

I should be able to receive, but not transmit on a modified VX-8R correct?

I am listening on several channels, but I am not hearing any chatter. I am wondering if I need to listen to a different channels or if I am doing something wrong.

C2 · #2 09-11-2009, 01:38 PM

The VX8R receiver in this band is not as sensitive as most quality CB radios, especially with the rubber duck antenna, you'll be lucky to hear anything. Probably just powerfull stations a couple miles away...

ke7vvt · #3 09-11-2009, 11:38 PM

kd8lwx - yes
c2 - yes

The closer and higher power the station is the better your odds are at hearing something. A different antenna will help the most, Associated Radio SO-239 to SMA Male Cable this little guy I think should let you connect to a CB antenna (I assume they use the UHF connector) and that will probably be as good as you can get on the RX end. It definitely would be an interesting test. Keep us updated as you find anything else out.

I'll tune into that band and see if I can hear anything.

c2, do you really think that the circuitry in the 8r would not be as sensitive near the 11 meter band provided you had the same antenna as any other CB radio?

KD8LWX · #4 09-12-2009, 12:10 AM

Thanks guys..

ke7vvt, This was an exercise in learning Freqs. and learning the radio. I will not be persuing it any further.

C2 · #5 09-12-2009, 03:05 AM

Quote:

Originally Posted by ke7vvt

c2, do you really think that the circuitry in the 8r would not be as sensitive near the 11 meter band provided you had the same antenna as any other CB radio?

Yes.

The VX-8R sensitivity spec is around 3.0 µV for 10dB S/N (0.5-30MHz, AM) whereas most CB radios are around 0.5 µV for 10dB S/N, AM.

Probably because the VX-8R has such a wide front end to cover the entire HF band with relatively poor filtering/IF gains and a cheaper detection circuit. Probably most of it is integrated into one IC. CBs just need to cover ~500 kHz.

Captain Kilowatt · #6 09-13-2009, 04:55 PM

Quote:

Originally Posted by C2

Yes.

The VX-8R sensitivity spec is around 3.0 µV for 10dB S/N (0.5-30MHz, AM) whereas most CB radios are around 0.5 µV for 10dB S/N, AM.

Probably because the VX-8R has such a wide front end to cover the entire HF band with relatively poor filtering/IF gains and a cheaper detection circuit. Probably most of it is integrated into one IC. CBs just need to cover ~500 kHz.

Consider too that those specs are ONLY guarenteed inside the amateur bands. Performance outside the amateur bands can vary from GREAT!

to dismal

at best.

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