RF Frontend template and basic now in github

[Steve Haynal]

Hello List,

I committed the kicad template (schematic, PCB and libraries) for designing your own RF frontend. I also created a first frontend project which is just the two RF connectors with baluns that are on revisions 0.9-1.1. You can find them at https://github.com/softerhardware/Hermes-Lite/tree/master/frontend. More documentation will follow. 

The basic frontend is an example of how I'd like to see these frontends done. Besides the source kicad design files, it includes two subdirectories with the gerber files all zipped up and ready to send to www.oshpark.com or www.iteadstudio.com. If you'd like to see what the PCB looks like, download http://gerbv.sourceforge.net/ (there is a Windows version) and look at the files in https://github.com/softerhardware/Hermes-Lite/tree/master/frontend/basic/oshpark. There is also a bom.xls file in the basic subdirectory. What is lacking is some documentation in github markdown format. The schematic for the basic frontend is attached.

I submitted the basic frontend to OshPark for $12.35 including shipping. This is for 3 boards. The boards are an odd shape as I was trying to save money but discovered that OshPark charges for the smallest enclosing rectangle. Later versions will be more rectangular. There are standoff holes on the RF frontenfd for stability. For these cards, one should request at least ENIG finish as they will be plugged into a PCIe receptacle. It would be better to do hard gold plating if I one of these fabricators will do this for reasonable cost. iTeadStudio charges $20 extra for ENIG but OshPark provides it by default. 

For those interested in designing their own RF frontend, simply copy the template folder to a new name. https://github.com/softerhardware/Hermes-Lite/tree/master/frontend/template There is a schematic with the EDGE connector already present. The PCB has the EDGE connector placed and edge cuts and mounting holes to match nicely with the Hermes-Lite. You just add your new components, route and finalize the edge cuts. It only takes a few hours. Once you are done, make sure to include a bom, documentation (in github markdown) and zipped files for fabricators. Send me a pull request from your github repository and I will include it in my Hermes-Lite github repository.

Who is ready to design an small PA?

73,

Steve

KF7O

[Zl2APV]

Hello Steve et al,

While you and Rob have been beavering away on the Hermes-Lite I have been working on a matching switched Rx RF Amp, filters and a small PA. All are working but not ready for publication due to some new ideas while experimenting etc. The small PA (5 Watts) needs wider bandwidth FETS and am looking at PA8005's. This was to be also a pre-driver for a 20 watt final which sets you up for driving a reasonably powerful Linear. I am looking for 6 M band as well even though the Hermes-Lite is targeted at the 160 M to 10 M bands. Unfortunately I can't do any more about it just now as I am heading off to VK in a few hours but will keep in touch. Same of course applies to the baluns.

73 Graeme

[Zl2APV]

Getting an error on Kicad as follows ...

Error loading board.
PARSE_ERROR: Expecting 'number' in input/source "/home/gvj/Programs/Hermes-Lite/frontend/basic/frontend.kicad_pcb", line 73, offset 23
from /build/buildd/kicad-0.20131208+bzr4024/common/dsnlexer.cpp : Expecting() : line 285

also get it on Hermes-Lite pcb but in too much of a rush to chase it up myself. If you are too busy also Steve it will wait til I get back.

Error loading board.
PARSE_ERROR: Expecting 'number' in input/source "/home/gvj/Programs/Hermes-Lite/pcb/hermeslite.kicad_pcb", line 76, offset 23
from /build/buildd/kicad-0.20131208+bzr4024/common/dsnlexer.cpp : Expecting() : line 285

73 Graeme

[Steve Haynal]

What version of Kicad are you using? Did it work with the any of the earlier revisions?

73 Steve

[Graeme Jury]

Sorry, but no computer for next 2 weeks. Using version that is in repository for Linux Mint 17 (Ubuntu 14.04

73 Graeme

On 21/10/2014 2:39 PM, "Steve Haynal" <softerh...@gmail.com> wrote:

What version of Kicad are you using? Did it work with the any of the earlier revisions?

73 Steve

--
You received this message because you are subscribed to a topic in the Google Groups "Hermes-Lite" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/hermes-lite/blS-Ecn22TA/unsubscribe.
To unsubscribe from this group and all its topics, send an email to hermes-lite...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Alan Hopper]

Steve,

I also get the same error on windows build 2013/07/07 bzr 4022.

Alan

On Tuesday, October 21, 2014 2:39:41 AM UTC+1, Steve Haynal wrote:

[Steve Haynal]

I use a newer version of Kicad and it turns out the file format can't be read by older versions. See this bug. I currently use KiCad 2014-08-5 BZR 5054, but plan to update soon. You can:

• Download a newer version for windows or linux from here.
• Use a PPA or the kicad install script as described here for linux.
• Delete the offending line from the kicad_pcb file (it is plain text) so that you can view the design. It will corrupt the specified layers so shouldn't be used for development.

73,

Steve

KF7O

[John Williams]

Graeme,

Are you ready to let us look over your shoulder a bit on your design? This is exactly what I am thinking of...

John - AC9HY

[Zl2APV]

Hi John,

Yes happy to post what has been done so far. I have a driver which I am going to increase the output power from 2 to 5 watts by changing the fets to pd85004'see. Have a 20 watt final with rd16hhf1's. A pin diode t/r switch using cheap power diodes (I found a better diode than 1n4007's). Have a set of mesh filters for rx & lp for TX and currently fiddling with best way to switch them. I have a Norton preamp 10 db gain and about to experiment with high speed analog switches to switch in and out. I don't have a Web site but can post on github anything you may be interested in. Currently I am away in my caravan whitebaiting but back in a couple of days.

73 Graeme zl2apv

[Zl2APV]

Hi John, I guess we need to start comparing notes. I currently have a HiQSDR for my test bed and have made an interface board to provide TX switching delays, pa bias delay and isolated via opto couplers. The HiQSDR provides 4 lines for a 4 of 12 decoder for filter switching and a tx/rx line. It would be good if we can get similar from Hermes-Lite.
whitebait are a tiny fish from the galaxid family which swim from the sea& migrate up river.

73, Graeme

[Robert Nickels]

On 11/21/2014 2:36 PM, Zl2APV wrote:
> I have a Norton preamp 10 db gain and about to experiment with high speed analog switches to switch in and out.

That's all great work, Graeme! For receive-chain RF switching you
might have a look on the Peregrine PE4259, which is an SPDT switch
that's just under a dollar from DigiKey. They're spec'd from
10Mhz-3GHz but so are the ones Elecraft uses and it looks like the part
will go down to 1.8Mhz without issue.

73, Bob W9RAN

[Zl2APV]

Hi Bob,

Thanks for the info and the pointer to the PE4259. It is a very interesting chip and I am very keen to try it below 10 mHz and see exactly how much degradation there is; I suspect very little. My experiments have been with the ADG779BKSZ which is really good except for the fairly high capacitance 7 pF when off and 25 pF when operated. Not too bad for an amplifier but needs to be absorbed if switching Rx filters above 10 Mhz. I am starting to see a combination of chips here. One advantage of the ADG779BKSZ is a 5 Volt Vdd rail but 3.3 Volt is still OK as I sure hope I am not bombed with signals in that order. I like the PE4259 price and am mindful of Steve's original stipulation that the project is to have a strong bias towards low cost.

73, Graeme zl2apv