Re: Setup FM mobile VHF transceiver's deviation with VaraFM
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Does anyone read the specifications?? Or they may read them but have absolutely no understanding of what they entail.? Yes, for faithful representation of the input, -25 dBm is specified. ? In an attempt to keep things simple, every 10 dB is equivalent to multiplying by 0.1, or move the decimal point one place to the left.
5-watts: ? add 10 dB attenuator ?? end with 0.5 watts? 5-watts ?? add another 10 dB attenuator for a total of 20 dB ? end with 0.05 watts 5-watts ?? add another 10 dB attenuator for a total of 30 dB ? end with 0.005 watts 5-watts ?? add another 10 dB attenuator for a total of 40 dB ? end with 0.0005 watts 5-watts??? add another 10 dB attenuator for a total of 50 dB?? end with 0.00005 watts
We all (should have) learned base 10 arithmetic in grade school.? Logarithms in Jr. HS or beginning HS.??
Dave - W?LEV
Also be aware that even at -10dBm, which is well below the damage level, the TinySA may still be slightly overloaded and not give accurate results on some measurements. At least 60db of attenuation would be required for a 5W input.
An input of -25dBm or less is recommended.
73
Jeff G8HUL
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From: [email protected] <[email protected]> on behalf of Gary W9TD via <w9td=[email protected]>
Sent: 11 November 2024 18:43
To: [email protected]
Subject: Re: [tinysa] Setup FM mobile VHF transceiver's deviation with VaraFM
Todd,
You need 50 dB of external attenuation to keep the level at the Ultra at -10dBm or less. You also might be able to use the supplied antenna with your radio feeding a dummy load. You cannot use the VARA modem as it will not create a single frequency tone, you need an external audio source like Audigy on your computer to generate a tone and send it through the USB to the DRA-50.
Gary
W9TD
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