[hpsdr] VHF-millimeter up/down converters?

[Glenn Elmore]

Joe,
That trying to push direct ADC/DAC conversion higher is not the way to 
do this is my opinion also. However, I'd rather not do it with they 
typical banded approach. That is dedicated per-band filtering 
accompanied by a clean LO and mixers to simply move the Angelia (or 
whatever) spectrum to and from an amateur band.

Rather, I'd like to add an additional conversion with a similar LO to 
above the highest range of a wide-range clean LO that can be locked in 
50 MHz or smaller steps down to some much lower frequency.  Looking at 
it in the receive direction, set the variable LO below that higher IF to 
downconvert the previously upconverted band or [50 MHz] range range/band 
of interest.  Reverse it on TX.

These are exemplary numbers only for receive, not actual choices:


[100 MHz through 3500 MHz] input goes through 5400 MHz multi-section LPF 
to  Mixer1.
LO1, steppable 5650 - 2150 MHz  goes to Mixer 1  to gives 25 MHz wide 
IF1 = ~5700 MHz.
After BPF, IF1 goes to Mixer2.
LO2 fix tuned at [5425 MHz] goes to Mixer 2.
[275-300 MHz] output of Mixer2 filtered in 25 MHz BPF=IF2 goes to Mixer 3.
IF2 goes into Mixer3.
LO3 = fixed 250 MHz goes into Mixer 3.
Output of Mixer3 is 25-50 MHz goes to Angelia.

Turn it around, use mostly common LOs (probably duplicate LO1 for 
transmit to maintain high tx/rx isolation)

This is the general approach used in RF-microwave spectrum analyzers, 
also turned around for TX.
I need to draw this but can't do it without more than ASCII.

Glenn n6gn


Inputs from Mixer1 and LO2 to Mixer2 takes this IF2 and converts in down
On 04/18/2015 10:53 PM, Joe Martin wrote:
> Hi Glenn,
>
> FYI, I am routinely using the ANAN-100D (it contains the Angelia transceiver board) to do pulsar radio astronomy at 424-436 MHz and hydrogen-line work at 1420.2 MHz by using the ANAN-100D as an IF stage in the radio telescope.  To access the UHF/Microwave frequencies with the ANAN-100D I use the appropriate LNAs for the band of interest (out on  the dish) and a MiniCircuits mixer and 50 MHz low pass filter in the shack that feeds the ANAN-100D, typically using a 28 MHz IF from the mixer but I also use 40 MHz IF occasionally; the ANAN-100D receives those IF frequencies fine.
>
> Using down converters appears to work much better in terms of weak signal sensitivity than does striving to make the Angelia operate at frequencies higher than 60 MHz directly.
>
> 73, Joe K5SO
>
>
> On Apr 18, 2015, at 3:50 PM, Glenn Elmore wrote:
>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> I'm a total newbie on this list. I hope this is an appropriate posting.
>>
>> I'm wondering who might have worked on, or be working on, frequency extensions for OpenHPSDR.  Specifically, it seems to me that an effort to extend the range of OpenHPSDR to include 50 MHz - 6 GHz or higher must have been considered if not attempted or accomplished by someone by this time.  Who has done this or might be interested in discussing it?
>>
>> I'm asking because, although new to OpenHPSDR with an Angelia just freshly boxed up and working, I already see the desirability of having coverage of 144,220,432,900,1296 and 2304. It seems to me that it would be a shame to limit this to a conventional banded transverter approach and that doing a conversion to a higher fixed IF followed by a down conversion to cover,say 50 MHz to 6 GHz with a clean LO up/down converter is an obvious choice.  Allow this is a "radio" project, continuous coverage would allow extension of signal analyzer and vector network analysis throughout this range and should be a pretty useful capability.
>>
>> Is this already being done by someone?
>>
>> Glenn Elmore
>> n6gn
>>
>>
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>


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