[hpsdr] Possible 5 band VHF transverter?

Dick Faust k9ivb at cox.net
Fri Mar 15 12:59:42 PDT 2013 

Hi

Would someone, briefly, outline how and where you can get the phase lock 
signals from Hermes.  The Atlas Bus boards are more obvious.

Thanks

Dick K9IVB

Helmut, DC6NY wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi,
>
> Kjell, basically you are absolutely right. The AD9915 would be really fine, but very expensive (USD 108.--) and an 88-lead LFCSP package. On the other hand I also think it’s better to use PLLs locked to Hermes and no other independent signal source.
>
> 73, Helmut, DC6NY
>
> -----Ursprüngliche Nachricht-----
> Von: hpsdr-bounces at lists.openhpsdr.org [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Kjell Karlsen
> Gesendet: Freitag, 15. März 2013 09:50
> An: hpsdr at lists.openhpsdr.org
> Betreff: Re: [hpsdr] Possible 5 band VHF transverter?
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> 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
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>
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>   

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