Re: LF: Fw: : Re: [rsgb_lf_group] Re:: 100KHz-1.7GHz full band UV HF RTL-SDR USB Tuner Receiver: How to get HF to work?

["Graham" <g8fzk@g8fzk.fsnet.co.uk>]

Thanks Mal,

 

Tom , wired them direct  last  night  .... interesting  angle , seems they  have  dropped  half  of  a  normal  dongle  into  a  docking  board , The  issue I was  interested  in was the  Ae  feed  for  low  bands  , and from the  image , its  visible , that the feed is  single  ended , via the  toroid ., he  also  plotted the  gain , which  falls  off  to  LF , which  is  similar to the  device  being   Cap   coupled  , both are  single  ended methods ...  100KHz  is  listed  as the  lower  operating  frequency  , in this  case its  possible the  transformer is  the  reason  ......

 

I think a  small   pre-amp [ 10 dB ?] with  gain  roll  off  to  HF would  be a better  option  , as the  chip  works  in  a direct coupled  set up  , down to  audio , a pre amp  could  also  provide the  ~~ 200 ohms  input  match as well  

 

But for  round  £10/15  supplied  as-seen  not a  bad  option

 

73-G,

From: mal hamilton

Sent: Sunday, June 29, 2014 8:31 AM

To: rsgb

Subject: LF: Fw: : Re: [rsgb_lf_group] Re:: 100KHz-1.7GHz full band UV HF RTL-SDR USB Tuner Receiver: How to get HF to work?

 

----- Original Message -----

From: DK1IS DK1IS@kabelmail.de [rsgb_lf_group]

To: rsgb_lf_group@yahoogroups.co.uk

Sent: Saturday, June 28, 2014 12:09 PM

Subject: Re: : Re: [rsgb_lf_group] Re:: 100KHz-1.7GHz full band UV HF RTL-SDR USB Tuner Receiver: How to get HF to work?

 

Hello Graham,

Please see below!

73,
Tom,DK1IS

Am 27.06.2014 22:52, schrieb g0nbd@hotmail.com [rsgb_lf_group]:

 

Tom,

At least  its  running  !

Yes it is and not so bad!

'' only the q-input works''

This only means that if you click the ExtIO button at the HDSR user interface "RTL Setting" offers to you at Direct Sampling "Disabled" (for VHF/UHF), "I input" (no stations at HF, only noise) and "Q Input" (stations at HF).

Do I assume, that  they are  using  a  single  ended  feed  for  the  low  band ?

Having no datasheet for the RTL2832U I´m not sure about this. As you can see on the picture enclosed at the lower side of the pcb there is a small ferrite toroid for the HF signal with two output wires, first being fixed with silicone on the RTL2832U housing and then going to two adjacent pins of the IC - whatever this means.

Is there  some  form  of  pre-amp  / pass  band  filter  before the  input ?

There is no pre-amp but you can see a two stage low pass filter on th left side of the ferrite toroid (two coils and 6 capacitors)

73-G,

 

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Posted by: DK1IS <DK1IS@kabelmail.de>

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