6m, 4m and 2m using Hermes Lite

[Duncan Clark]

Hi Folks,

As others have shown previously 6m can be used with one's Hermes-Lite
through undersampling, although mindful of any spurii particularly for
6m Tx.

I have been looking at what G4JNT has done for the Elad FM-Duo.

http://g4jnt.com/FDM-DUO_at_VHF.pdf

I finally got around to etching some pcbs and populated a 2m and 4m
version today. 6m one will be finished off tomorrow.

Suffice to say that although the 2m undersampling works with Hermes
Lite, using a signal generator, it is not un-surprisingly pretty deaf.
The AD9866 is just not designed for use at 145MHz.

However at 4m, Hermes-Lite appears to work very nicely. I don't
currently have a 4m antenna but my 10m cubical quad is doing a good job
of rxing the 0.5W G4JNT 4m beacon 120km away.

Now the only niggle left is how to make PowerSDR understand
undersampling or if it knows about it, what menu is it hidden in?

For 4m I use 6.8MHz for HL2 which gives 70.0 MHz rx. However 70.1MHz
would be 6.7MHz and so on. I can tell PowerSDR via the transverter
function to display 70MHz in place of 6.8MHz but it tunes backwards so a
70.1MHz signal is displayed as 69.9MHz.

Anyone know how to make PowerSDR behave correctly?

Duncan


--
Duncan Clark
G4ELJ

[Alan Hopper]

Hi Duncan,

SparkSDR still has all the undersampling code in it so you can tune directly and usb and lsb don't flip. I don't believe you can make powersdr do this just by using settings, if you want to mod the code it should be fairly easy, the software does need to know the radio clock frequency.  I can't remember if the internal lpf is used at the moment, turning it off did make a difference when I played with it, I got good results on 6m and bearable fm broadcast.

73 Alan M0NNB

[radi...@mail.com]

Hi Alan

Now we are coming into the Es season and 6m is being really quite active, I just wondered if you (or anyone else reading) experimented further with undersampling to avoid use of a transverter on 50MHz? Sorry if a silly question but would this also allow TX on 6m? Where are settings on Spark to allow the use of undersampling and Alan, I was not totally clear if you did any hardware mods on HL2 when you did your earlier experiment or just a matter of selecting the N2ADR filter board to bypass?

Thanks for looking.

Max

[Matthew]

Hi Max,

I have never done anything on 6m but set myself a goal of getting going on it this year. I've designed a transverter board that has the same footprint as the N2ADR board (main connectors all in the same place). The clock is via a ufl connector that will come from the HL2 PCB. I decided not to fit a PA to this PCB revision, so it will be around 100 mW output. The design should work from 6m to 70cm (with filter/component changes). There is nothing novel, just a fairly standard transverter design. I am planning to build and test a PD85004 driver to get the output up to 1-2 W (again, should work 6m to 70 cm). Perhaps this can fit on the PCB in future? I've used 0603 components and there is a bit of space still.

I really need to pull my finger out and finalise the PCB design and get a prototype built. I was waiting for a few other PCB designs to finish and I was going to order a panel. But I might just order these. Not that cost makes too much difference, but I managed to keep it on 2 layers and maintain 50 ohm tracking. Once I get it ordered, I'll tidy up the files and of course it will all be open source on github.

Perhaps if you don't mind 0603 soldering and a bit of early hardware adoption this could be of interest?

73 Matthew M5EVT.

[Alan Hopper]

Hi Max,

there are no special settings for this in Spark, you just tune to the frequency of interest, with a standard HL2 you will just get hf aliased at the higher frequency. To make 6m work you need to bypass the receive filter on the HL2 main board, I've never tried this.  There was a successful 6m tx design for the HL1.  With the bandwidth limits of the adc I think a transverter may be a better way to go.

73 Alan M0NNB   

[radi...@mail.com]

Hi Matthew and Alan

Many thanks for replies. I've actually picked up a couple of transverters, actually also for 144 and 432, but it's 6m that really holds my interest and was just wondering of possible to bypass the need for a transverter, but I from both your comments I guess as I expected the transverter is probably the sensible way to go, so will pursue that avenue.

Matthew, that transverter looks really neat. Wonder if you have considered how one might use several similar boards with input switching of some sort for a multi-band capability? That would definitely interest me in the future. I also like how it uses the clock from the HL2. Will be watching closely. For the time being and for speed as I am so poor for time, I will probably just crank my vintage transverters into action!

Forgive me for going slightly off-topic, but just a heads-up for those based in the UK who are interested in 6m/VHF and Es propagation in general I strongly suggest you look at the truly excellent resource that is Propquest, by Jim Bacon G3YLA. Predicts Es with the most astonishing accuracy (but also has other very useful propagation tools):

http://www.propquest.co.uk/about.php?section=maps

73

Max

On Monday, 31 May 2021 at 18:53:46 UTC+1 Matthew wrote:

Hi Max,

I have never done anything on 6m but set myself a goal of getting going on it this year. I've designed a transverter board that has the same footprint as the N2ADR board (main connectors all in the same place). The clock is via a ufl connector that will come from the HL2 PCB. 

73 Matthew M5EVT.

[Ulf Tjerneld]

I will also monitor your project closely. A transverter option  optimized for the HL2 is definitely something I’d love to have.
Es propagation in full bloom right now. I’m working with the HL2 and an Elecraft XV50. About 30 watts output when driven by the HL2. Extra cooling fitted for FT8.. 😊

 

Sent from Mail for Windows 10

--
You received this message because you are subscribed to the Google Groups "Hermes-Lite" group.
To unsubscribe from this group and stop receiving emails from it, send an email to hermes-lite...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/hermes-lite/95731190-adb3-4dea-acd7-9645d4ec65fbn%40googlegroups.com.

 

[gerry kavanagh]

So, start saving for another HL2...

This looks like an excellent project Matthew. Here in Ireland we also have access to 8m & 5m bands. Do you imagine it might work there also? 

/ Gerry

On Monday, 31 May 2021 at 18:53:46 UTC+1 Matthew wrote:

[J P Watters]

Matthew,

Just a thought, maybe there are limitations that would make it impractical use a piggyback design.

After thinking about your transverter board that has the same footprint as the N2ADR board, it could almost piggyback on top of the N2ADR board. 

I have added a couple of development boards to a couple of my HL2's for the just in case I decided to develop some addons. Currently mine only has the RF3 

connection soldered on the board to bring it out to the front panel. I had not got to a point that I had an addon to breadboard up and use.

My thoughts are that a HL2 could possibly then have a transverter added on without losing all of it's of the HF capabilities and possibly retaining some of them.

Controlling the transverter could maybe done with the bands (OC) configuration. Then selection of the band would 

activate the correct filter board and it's configuration. And a additional antenna jacks for VHF Antenna Output, as well

as several other sma antenna jacks could be added

Below is a photo of a development board that I added to my HL2. 

It was designed by Alex Alex Pressl https://github.com/pressla/HL2_Extension_Jumper

..jpw J P Watters

KC9KKO

Morris, IL USA

[Duncan Clark]

In message <a04fa06c-aa82-47cc...@googlegroups.com>,
Matthew writes

>I've designed a transverter board that has the same footprint as the
>N2ADR board (main connectors all in the same place). The clock is via a
>ufl connector that will come from the HL2 PCB. I decided not to fit a
>PA to this PCB revision, so it will be around 100 mW output. The design
>should work from 6m to 70cm (with filter/component changes). There is
>nothing novel, just a fairly standard transverter design. I am planning
>to build and test a PD85004 driver to get the output up to 1-2 W
>(again, should work 6m to 70 cm). Perhaps this can fit on the PCB in
>future? I've used 0603 components and there is a bit of space still.

If you are going to use PureSignal you will need two boards as you will
need to operate duplex. Ideally a low noise 'bomb proof' RF preamp
(PGA-103+) and high IP mixer. Lot of local UK stations with multi kw ERP
via stacked beams and 400W - let alone those with even higher power
licenses. I have several within a few mile radius.

For a PA, the R3KR 28dB Class A MRF300 design with BN61-202 ferrites
works very nicely up to 6m. Easy 10W with way less than 100mW drive.

https://www.youtube.com/watch?v=XnNE_jzhqFk

Sounds overkill but works fine with 28V and 3A using an old Pentium
heatsink/fan assembly. I use a homebrew copy with the HL2 PA switched
off.

[Matthew]

Gerry,

5m band almost certainly. 8m probably, but it might require some careful thought for a clock frequency and a quiet band to mix down to.

jpw,

I think what you are proposing is possible. The only problem I can see is that the receive signal from the N2ADR board and this board would both be connected (through J1 and J21 on the HL2). If you had an HF antenna connected to the N2ADR board this would likely cause problems of bleed through onto your chosen baseband. K2 would need to always be in TX position to avoid this, but I think it does the opposite of this in low power output mode?

Duncan,

Thanks for the link to the amplifier. I don't think I had seen that one. There were certainly lots of interesting designs that came out of that competition. I was planning to build the 50 MHz MRF101 datasheet amp so 10 W input is too much for this. For duplex, OH2GAQ has already done excellent work on this and there wouldn't be much point in me re-inventing the wheel there.

73 Matthew M5EVT.

[Mike Lewis]

Same here but have a stack of Elecraft transverters, 50 to 432, so switching logic (band decoding) solution comes to mind.  Longer term I see the HL2 with a Teensy SDR front end hooked to a Q5Signal.com 5-band transverter which uses a 28Mhz IF, still need a 6M xvtr.

To view this discussion on the web visit https://groups.google.com/d/msgid/hermes-lite/301B2B70-F8D2-420A-A3D7-2BFB9195B824%40hxcore.ol.