[hpsdr] Hermes 144mhz

[Kjell Karlsen]

Hi Bent.

Do you plan to use Hermes only for 144 MHz or are you going to use it on  
HF also?

If you mean to use it only on 2 meter, it should be possible to do the  
modifications both on the TX and RX. I have modified one of my Hermes  
boards so that I can take out the signal after FL1 so that I can use  
another amplifier but as the signal from T1 is unbalanced, the track  
between T1 and FL1 can be cut and connected to a SMB soldered and placed  
beside FL1.

On the RX side you can do a similar modification. Cut the track between  
FL6 and T4 and connect T4 to another SMB soldered to the GND placed beside  
FL6. Then recalculate the L/C filter between U11 and U10 for 130 MHz. The  
bandwidth of U11 and T4 is very high so that should not be any problem.

I am tempted to try this myself!

73, Kjell




På Wed, 10 Sep 2014 09:44:43 +0200, skrev Helmut Oeller <dc6ny at gmx.de>:

> ***** High Performance Software Defined Radio Discussion List *****
>
> It's necessary to substitute the two LPFs (RLP-50+ and the LPF between
> preamp and ADC) on the RX path by BPFs for 144MHz. On the TX side a BPF
> directly behind DAC is needed. IMO it's too cumbersome to provide these
> modifications on Hermes. It was much more comfortable to use Mercury and
> Penelope for this job. BTW the 122.800
> MHz sampling oscillator produces such low jitter that SNR is also very  
> well
> in undersampling application on 144 MHz.
>
> 73, Helmut, DC6NY
>
> -----Ursprüngliche Nachricht-----
> Von: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Ton
> PA0TBR
> Gesendet: Mittwoch, 10. September 2014 01:18
> An: hpsdr at lists.openhpsdr.org
> Betreff: Re: [hpsdr] Hermes 144mhz
>
> ***** High Performance Software Defined Radio Discussion List *****
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