how to controll this 2 attenuator ???

OZ1CT-Ben
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how to controll this 2 attenuator ???

Postby OZ1CT-Ben » Sun Dec 09, 2018 7:56 pm

Hi All

I have a Anan-100d and when I look at the schematic on the PA & LPF I can see 2 fixed attenuator (se picture) but how / where can I control this attenuator ???? in Powersdr ???
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Joe-W4WT
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Re: how to controll this 2 attenuator ???

Postby Joe-W4WT » Sun Dec 09, 2018 9:01 pm

If I remember correctly, it's been a while since I looked at this, this attenuator is used for Ext2/3 input. I believe it is 20db, if memory serves. I used to connect my low band Rx antenna to Ext2 until I found that this attenuator is switched in and there is no way I found to switch it out. I now use Ant 3 input for my Rx antenna which is not attenuated. Much better for a low signal Rx antenna.

Joe W4WT
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w-u-2-o
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Re: how to controll this 2 attenuator ???

Postby w-u-2-o » Sun Dec 09, 2018 9:17 pm

This is controlled from the main console via the ATT control. 10dB selects the 10dB pad, 20dB selects the 20dB pad, and 30dB selects both. If you select more than that the software starts to add in attenuation from the step attenuator IC on the SDR board itself.

If you want finer grain control than that, simple double click ATT and it will change to S-ATT. Then you are using the step attenuator, which will provide between 0 and 31dB of attenuation in 1dB steps.
Joe-W4WT
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Re: how to controll this 2 attenuator ???

Postby Joe-W4WT » Sun Dec 09, 2018 11:03 pm

Scott is, of course, correct. My mind is just not right.

73,

Joe W4WT
OZ1CT-Ben
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Re: how to controll this 2 attenuator ???

Postby OZ1CT-Ben » Mon Dec 10, 2018 5:54 am

Hi All

The reason why I aske is that when I use ANT1 my RX is very low sensitivity but if I change to BYPASS then the RX is at full sensitivity.

using hpsdr 3.4.9 and every time I startup I have to change the attenuator to 0 to get a good sensitivity.....have to figure out where det problem is becurse I realy like to have 3 antenna connected to my ANAN 100d :-)

TNX fer help...Ben
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w-u-2-o
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Re: how to controll this 2 attenuator ???

Postby w-u-2-o » Mon Dec 10, 2018 11:27 am

I'm not understanding where the problem is. With appropriate (good) band conditions best sensitivity is always achieve with zero attenuation.
OZ1CT-Ben
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Re: how to controll this 2 attenuator ???

Postby OZ1CT-Ben » Mon Dec 10, 2018 5:39 pm

Hi Scott

The problem is that when I connect a antenna to ANT1 the rx sencivity is very lov ...if I change to BYPASS the the RX is Good :-) so somthing is wrong ???

Ben
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w-u-2-o
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Re: how to controll this 2 attenuator ???

Postby w-u-2-o » Mon Dec 10, 2018 6:30 pm

Not enough information here to debug your problem :(

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