[hpsdr] Possible 5 band VHF transverter?

Fri Mar 15 01:50:16 PDT 2013

Hi All.

Why not consider using a DDS to generate the LO in a transverter? AD has  
many new chips that may be used. I know they may have some spurs but AD  
has described some methods to reduce them.

73, Kjell

På Fri, 15 Mar 2013 09:14:50 +0100, skrev Helmut, DC6NY <dc6ny at gmx.de>:

> ***** High Performance Software Defined Radio Discussion List *****
>
> Yes Conrad, I understand your plans, but it’s a pity to see Hermes
> performance decreasing, hi.
> You know these broadband VCOs produce terrible phase noise due to low Q
> circuitry. After  division by 64 or 128 PN gets acceptable on low
> frequencies. Perhaps you can use that method for  4m/2m/70cm and external
> small band VCOs beyond 1 GHz. Good luck!
>
> 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: Freitag, 15. März 2013 01:19
> An: hpsdr at openhpsdr.org
> Betreff: Re: [hpsdr] Possible 5 band VHF transverter?
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> I agree Helmut this approach will not be as good as a well designed 3rd
> overtone oscillator in the VHF region, however it will be acceptable.
> This transverter is a multiband device that will be much cheaper and
> smaller than the traditional topologies. It is not designed for a
> contest station on 2m on a hill top.
>
> The MAX2870 is not the device that I have in mind but the performance is
> only a little better.
>
> A low phase noise super linear transverter is a different exercise and
> one that I am really interested in tackling as well, but later.
>
> Despite that when coupled with Hermes it will be much better than the
> typical VHF radio and rather better than the run of the mill transverter
> designs that are out there. Not all Xtal oscillators are made equal.
>
> However at this stage until I have done more testing and looked at the
> reality of the spurs from the device and therefore the filter
> requirements I am not prepared to share a block diagram.... yet. When I
> have the building blocks in place and have tested them - and I have some
> performance figures I will of course be prepared to share.
>
> Can I just ask again (as I do not have a Hermes yet) is high side
> injection feasible with PowerSDR? On 70 MHz I would like to use high
> side injection. My LO frequency range with the proposed device is 85 -
> 2700 MHz.
>
> I am chiefly interested in weak signal modes such as EME and close in
> phase noise is not that important to me, I don't have any truly strong
> signals above 50 MHz locally. I do have some stations who are quite
> strong and clearly have their own phase noise issues :) Improving things
> my end won't make any difference with those guys; fortunately they go to
> bed early.
>
> If any one has any ideas for a multiband transverter that can achieve
> -146 dBc @ 10 kHz I'd love to hear your ideas.
>
> So to summarise, my design as it stands will degrade Hermes by up to 20
> dB/Hz @ 10 kHz offsets above 432 MHz however it will be a Hermes sized
> box that will do at least 5 bands. When I know that it will work I will
> publish a block diagram and ultimately construction details, pcbs etc.
>
> For the best strong signal handling mono band transverters with LO based
> upon a Xtal still wins out from what I have seen so far, I just fancied
> doing something a bit different.
>
> Whatever I do its got to be better than the awful Icom IC910 that we
> have at our radio club!
>
> 73
>
> Conrad G0RUZ
>
>> Hi Conrad and Phil,
>>
>> I’m afraid the even the MAX2870 is no good choice. A 5 band application
> 4m,
>> 2m, 70 cm, 23 cm and 13 cm, requires LO-frequencies between 20 and 2400
> MHz
>> assuming an IF covered by standard HPSDR. MAX 2870 datasheet shows phase
>> noise between -130 dBc/Hz and -100 dBc/Hz@ 10 kHz offset for these
>> frequencies. This is at least 20 dB worse than the traditional design
> using
>> a xtal-oscillator an multipliers and will reduce the TRV performance
>> dramatically.
>>
>> 73, Helmut, DC6NY
>>
>> -----Ursprüngliche Nachricht-----
>> Von: hpsdr-bounces at lists.openhpsdr.org
>> [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Phil Harman
>> Gesendet: Donnerstag, 14. März 2013 11:55
>> An: Conrad Farlow; hpsdr at openhpsdr.org
>> Betreff: Re: [hpsdr] Possible 5 band VHF transverter?
>>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Hi Conrad,
>>
>> You may like to consider the MAX2870 integrated VCO/Synth.  I've been
>> evaluating one for the Cyclops Spectrum Analyser project and the phase
> noise
>>
>> is quite good in comparison to other devices.
>>
>> 73 Phil....VK6APH
>>
>>
>>
>> -----Original Message-----
>> From: Conrad Farlow
>> Sent: Thursday, March 14, 2013 11:34 AM
>> To: hpsdr at openhpsdr.org
>> Subject: Re: [hpsdr] Possible 5 band VHF transverter?
>>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> I am working on a multiband transverter for Hermes, its early days but I
>> have narrowed down my choices of Silicon. It will be possible to lock to
>> either the 122.88 MHz Hermes oscillator or a 10 MHz ext source . It's a
>> synth but the phase noise is very reasonable for an integrated VCO/Synth
>> based design .
>>
>> I had forgot about 220 MHz but there is no reason why it could not be
>> accommodated.
>>
>> I hope that the transverter will work up to 13cms and down to 4M.
>>
>> TX Output will be of the order of 23 dBm with some 10W amplifiers to
>> come later. This seems to be a sensible output power given the drive
>> requirements of a modern LDMOS devices.
>>
>> I still have a LOT to sort out but so far I am very encouraged that I
>> can make this happen and that the transverter will be better than older
>> designs and will use modern devices that should have a long shelf life.
>>
>> I will post some performance figures as I develop the boards, I expect
>> that it will take me 6 months or so to complete with my current  
>> workload.
>>
>> 73
>>
>> Conrad G0RUZ
>>
>>
>>
>>> ***** High Performance Software Defined Radio Discussion List *****
>>>
>>> This chip has been around for a couple of years, but this board might
> make
>>> a nice transverter for Hermes.  6 dBm out.  Too bad it won't reach down
> to
>>> 2M and 220.
>>>
>>> http://myriadrf.org/
>>>
>>> The Kickstarter Blade project would be more in line with this board,  
>>> but
>>> only has a 12 bit receiver.
>>>
>>> N0UU
>>> _______________________________________________
>>> HPSDR Discussion List
>>> To post msg: hpsdr at openhpsdr.org
>>> Subscription help:
>>> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
>>> HPSDR web page: http://openhpsdr.org
>>> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>> _______________________________________________
>> HPSDR Discussion List
>> To post msg: hpsdr at openhpsdr.org
>> Subscription help:
>> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
>> HPSDR web page: http://openhpsdr.org
>> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>>
>> _______________________________________________
>> HPSDR Discussion List
>> To post msg: hpsdr at openhpsdr.org
>> Subscription help:
>> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
>> HPSDR web page: http://openhpsdr.org
>> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>>
>
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at openhpsdr.org
> Subscription help:
> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
> HPSDR web page: http://openhpsdr.org
> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at openhpsdr.org
> Subscription help:  
> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
> HPSDR web page: http://openhpsdr.org
> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>
>

-- 
Sendt med Operas revolusjonerende e-postprogram: http://www.opera.com/mail/

 1363337416.0