[hpsdr] A few questions

Mon Feb 18 06:52:33 PST 2013

Hi Conrad,

correction:-151 dBc/Hz @ 10 KHz offset- 

73, Helmut, DC6NY
-----Ursprüngliche Nachricht-----
Von: hpsdr-bounces at lists.openhpsdr.org
[mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Conrad Farlow
Gesendet: Montag, 18. Februar 2013 13:11
An: hpsdr at lists.openhpsdr.org
Betreff: Re: [hpsdr] A few questions

***** High Performance Software Defined Radio Discussion List *****

Where can I find a plot of the Hermes 122.88 MHz clock phase noise.

__________________________________________________
73

Conrad G0RUZ IO93FR
__________________________________________________
On 18/02/2013 08:10, Helmut, DC6NY wrote:
> Hi Conrad, hi Phil,
>
>
> I‘m successfully operating a 2m homebrew transverter using a +13dBm
> Mini-Circuits ADE-25 mixer for rx/tx path, a 3-pole Temwell helical BPF
and
> some MMICs with Hermes but also with Mercury/Penelope/Metis. I prefer
Hermes
> due to minimal spurs on 10m IF.
>
> As Phil mentioned low  phase noise of the transverter LO is most important
> for the total performance. It’s a really good idea to use the 122.88 Mc
also
> as LO for the transverter.  If there is interest enough it should be no
big
> deal to design a PCB.
>
> 73, Helmut, DC6NY
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: hpsdr-bounces at lists.openhpsdr.org
> [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Conrad Farlow
> Gesendet: Montag, 18. Februar 2013 04:02
> An: phil at pharman.org
> Cc: hpsdr at lists.openhpsdr.org
> Betreff: Re: [hpsdr] A few questions
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Phil well if no-one is designing transverters then some one should
> be! I suggest that we start the discussions by setting some performance
> goals, the last thing that we want to do is compromise the excellent
> receiver by limiting dynamic range due to excessive gain or choosing
> devices that don't cut the mustard.
>
> Your comment on the LO is very interesting, using a 21.12 IF will still
> allow the use of sensible and achievable filters at 144 MHz. I rather
> fancy using active mixers for all transverters these days although I
> haven't really examined everything that is available yet. Transverters
> for bands above 70cms should probably use a locked synth LO as these are
> capable of excellent performance these days. I presume that it is
> relatively easy to tap off a small amount the 122.88 MHz clock? Active
> mixers only need small amounts of LO drive (-5dBm)  and offer good RF-LO
> and IF-LO isolation and don't need terminating with fancy diplxers which
> are the compelling reasons for using them.
>
> Interesting times ahead.
>
> __________________________________________________
>
> 73
>
> Conrad G0RUZ IO93FR
>
>
> On 18/02/2013 01:58, Phil Harman wrote:
>> 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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>>>

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