Low power out for amp.

[Jeff Scaparra]

Hello I recently got my hl2 and it was good timing cause I had to send my flex in for some repairs. My amp is a modified HR 50 that only needs 100mW for the 50 out. Even with drive level set to 1 I am getting too much power out. Is there anything short of adding more attenuation to the input on my amp that i can do? I am using linhpsdr.

[Steve Haynal]

Hi Jeff,

Are you using the switched ANT connector, or do you have the HL2 configured to use the low power output RF1? See the videos linked to on the software wiki page for details on enabling the low power output. The low power output has 17 to 20 dBm even with full drive level. 

https://github.com/softerhardware/Hermes-Lite2/wiki/Software

The AD9866 power output can be adjusted over a range of 7.5dB, highest power down to 7.5dB less. Beyond that you can reduce power output by reducing the amplitude of the signal sent to the HL2, but that gives up some bits of DAC resolution. You can customize the output levels of your HL2 by changing the value of R55. Search for R55 in this group.

73,

Steve

kf7o

[Jeff Scaparra]

Hey thanks steve for the reply I ended up removing the driver amp from the hardrock. The low power only got me to 17W at max power and I didnt see how to make that work without a separate tr switch to use the same antenna. Didnt want to mess with all that.

So far the Hermes lite 2 has performed better than I thought it would... makes me wonder if we really need 16 bit adcs... of course there is a difference on paper but in operations how much of a difference is there.

My flex 6600 is currently at flex for repair when I get it back I plan on making a comparison using ft8.. only using the rx to see how much more the flex really can pick up.

Jeff

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[si...@sdr-radio.com]

Jeff,

 

16 bits vs 12-bits is ~ 24dB dynamic range assuming good engineering practice in both implementations. If solar cycle 25 actually happens as predicted then we may see HF signals which could test a 12-bit ADC.

 

FWIW there was a massive E’s opening on 2m yesterday from the UK (Cornwall) to Finland, I was seeing a station OH5LK 70dB above the noise, a local is 104 dB SNR on the back of my 2m beam.

 

So you can do a very great deal with just 12 bits, but more is always nice to have.

 

Simon Brown, G4ELI

https://www.sdr-radio.com