[hpsdr] A few questions

[Phil Harman]

Hi Conrad,


Welcome to the group. As far as I'm aware no one is developing
transverters for use with Hermes. However, existing transverters are
successfully being used with Hermes via the transverter port.

In order to use undersampling with Hermes you would need to remove the LPF
at the front end and the LPF following the pre-amp.  I've used
undersampling to test receive on 2m, it works but needs a good preamp to
be make an effective receiver.

There are some spectrum analyser images of the output of Penny on the
Wiki. I would expect Hermes to be similar. The 14 bit DAC will provide a
limit to the performance of the transmitter.

I've use the output from Penny as the RF source for a 2m Chirp beacon. I
did use a BPF in order to attenuate the 122.88MHz clock but apart from
that the source is very clean.

I've also used the 122.88MHz clock as the LO for a 2m Rx converter - since
it is very low phase noise ( <-130dB/Hz at 200Hz) and can be phase locked
to an external 10MHz reference the performance is excellent.

Please let they group know if you intend to design transverters since I
would expect there will be considerable interest.

73 Phil...VK6APH




> ***** High Performance Software Defined Radio Discussion List *****
>
> Hello all, firstly let me begin by apologising to the group if any of
> this information is available by reading hpsdr list archives, if they
> exist please point me to them.
>
> I am really only interested in 6m and above and so will require some
> transverters, I am seriously considering designing some transverters
> specifically designed to be used with Hermes. If anyone is already
> working on this I would like to hear about it.
>
> My intention is to purchase an Apache radio, I haven't decided whether
> to buy a ANAN-10 or their version of a Hermes yet. I have a high
> linearity 30W PA that I could use as a driver for 6m.
>
> Anyway a few questions.
>
> 1. Has anyone successfully tried to undersampling for 70 MHz and 144 MHz
> 2. Are there any plots of the TX output from Hermes - specifically TX
> spurs - do I need  a BPF in the upconversion path of any transverters?
>
> --
> __________________________________________________
>
> 73
>
> Conrad G0RUZ IO93FR
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