[Hackrf-dev] Rf amplifier not working

Giuseppe Marullo giuseppe at marullo.it
Sun Feb 11 08:00:09 EST 2018


Hello Mitja and Michael,

I knew the link, but my problem is that at the moment I could only use 
Windows (*long* story, I selected a AMD R9 280 to play with 
ESX/DirectPath I/O and linux support for AMD R9 sux), so my option to 
understand the problem is tied to use SDR Console by sdr Radio and SDR 
Angel. I don't know how to "map" rf amp to rx/tx gadgets on the gui.

On SDR Console 2.3 (used for Rx only), I have the following controls:

LNA (0-40dB, defaults to 24dB)
VGA (0-62 dB defaults to 20dB)
Ext Amp (off/On defaults to Off)

Listening to FM broadcast radios, it works if I keep Ext Amp off (it 
should be used only in TX, right?). Changing LNA and/or VGA 
increase/decrease the received signal and this is fine. Which is the 
supposed behavior when I switch Ext Amp on during RECEPTION? Is it okay 
that received signal weakens almost to vanish?

I ask this because I would expect no impact since the PA should not be 
activated on reception, or am I wrong?

On SDR Angel(used for RX AND TX), same controls and same result on Rx.

When I try to transmit I have a signal, but if I engage the ext amp 
almost nothing comes out. I use a dualband/DMR handheld almost one meter 
near the HackRF antenna.

I am asking because I would like to know if I need to change just the PA 
or also the rf switch are involved. I would order a couple of them (two 
amps and two switches) but it seems that the switches are way nastier 
than the amplifiers to solder so I would know for sure if the behavior 
is related to just the PA being broken or worse.

I fried mine probably using a 1.2m 5/8 mobile antenna too near to the 
DMR handheld to receive DMR transmissions.

 >By the way, your mail client has done an unneighborly thing in 
designating your
 >email as multipart/alternative with an empty text/plain section. In 
some mail
 >clients (and probably the mailing list digest) this makes the body of your
 >message appear empty

Interesting reading: https://stackoverflow.com/questions/8320141/multipart-alternative-subtype-when-client-use-it

Usually I send out messages using Automatic format and my email client is Thunderbird. This is the first time I get problems using it. If you don't mind could I send to you a couple of test messages, one encoded in text only and the other in auto to see what you do receive.
BTW, which email client are you using?
I am not a fan of HTML messages, I do rather prefer old plain text, and my impression was that it was what I was going to send using Auto on a new (blank message), more than willing to keep text only as default(and not a double whatever format), thank you.

Giuseppe Marullo

IW2JWW - JN45RQ

ps: this answer is plain text only, hopefully it will be okay



More information about the HackRF-dev mailing list