EMRFD Message Archive 14661

Message Date From Subject
14661 2018-04-28 11:47:57 zf2scka9p FAR HyCas Circuit Board
Curious if anyone has successfully built the FAR circuits HyCas circuit board. 
I was doing some post-stuffing resistance checks before powering up and I think I've found at least 5 missing grounds, which makes me wonder if there might be more, or possibly an errata list for this board?
Any input would be very helpful and much appreciated.
Thanks, Scott ka9p
14663 2018-04-28 16:48:41 Steve White Re: FAR HyCas Circuit Board

Far Circuit boards do not have plated thru holes, so maybe that is the ground problem.  I ran into this with the Progressive Receiver circuit boards.   NO VIAS!!!!


Steve NU0P


14670 2018-04-29 08:27:08 jim_amos_n8cah Re: FAR HyCas Circuit Board
Hi Scott,

Yes, I've successfully built one from the FAR boards.  It was a you describe though, with a lot of missing grounds and a few other things...  I went over what I did, and the notes written on my schematic and article pages  So, here are the list of changes that I had to make:

R1, C7 - GND (tied together but missing GND)
R2 - GND
R30 - GND
C6 - GND
C16 - GND - See note below
Q9 - Collector GND
Q10 - Missing Emitter GND, but also, Base pin needs drilled out to prevent grounding
Q12 - Emitter GND

On my board, I've got the GND side of C16 tied directly to GND, and left R5 out.   R5 and the collector of Q9 are tied together, but lack a GND connection anyway.  There are some notes regarding R5 and the AGC Attack in the errata to ponder.

There is also an errata list that was from the W7ZOI seb site.  So, I did make some of those changes:

R37 to 10K
R1 to 1K
L2, L3, L4 changed to 47 uH

Some area's are not critical though, and I made a few changes to fit parts I had on hand.  On my board, instead the LM337, I used a 9V  3  terminal regulator that I had on hand.   So, I was able to leave off the resistors that set the output voltage. Also, I changed the .22 uF caps, to 1uF Tant caps on the input and output.  I had a 1K 10 turn pot for gain adjust, so I changed R33 to 220 instead of 2.2K.   I used a transformer input circuit instead of the LC matching circuit.  

It did take longer to get the circuit working due to the number of issues with the board.  I've still got a second board, but would probably get a different board made if I were to build a second circuit.   But, once working it has worked very well with the gain provided matching spec.  Also, If I were to do a board, I would add locations for SMA connectors.

I'm using it with a 9MHz IF receiver at this  point that uses a 4 pole band pass filter, a 7 dBm diode mixer with a 2N5109 post mixer amp, and a Showa 9 MHz SSB filter, or home brew crystal filters.   I'm using Si5351 for LO and BFO (Arduino based controller), and it's a pretty good receiver.  I'm still experimenting with the filters though.

Let me know if you have any other questions, I hope this helps!


14673 2018-04-30 17:56:59 zf2scka9p Re: FAR HyCas Circuit Board
Thanks Steve.  Yeah, even after dealing with the no thru hole plating issue, I've got at least 5 spots where there are pads on both sides of the board that are pads to nowhere, and in each case where there is a missing ground.
It kinda looks to me like in many places the wrong type of pad on the top side of the board was picked in the artwork, should have traces to the ground plane rather than isolated pads, there are both kinds on the top side and probably easy to confuse - but I'm not an expert on the process.
I have heard from a couple other guys with similar experiences so am trying to get a comprehensive list together of what that board needs, to send to FAR  so they can either fix the board or pass along the patches.  I doubt they sell a lot of them these days, but everyone I talk to that's built one remains impressed.
If anyone else has anything for a list of issues on that board, please let me know so I can add it to the list.
Thanks, Scott
73 Scott
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14674 2018-04-30 17:57:00 zf2scka9p Re: FAR HyCas Circuit Board
Jim, you are a gentleman. a scholar, and an engineer!  And I owe you a couple 807s if we're ever in the same place.
I'd just sat down with coffee, a VOM, a bright light and a magnifying glass to start going over the board top to bottom when your note came through, and you've saved me a ton of time, as your list has 5 issues I hadn't yet identified.
In case anyone else is doing this, the only things I found that weren't on your list are:
1) Q11 emitter ground missing, same situation as Q10 and Q12; and
2) this may be board specific, but on mine, there was a tiny bridge in the top side of the board that would interfere with using a 3 pin connection to an off board R6, if set up that way.
I figured R5 would be an experiment, so had put a couple pins and a jumper plug there, so that I could off board a pot for that, and found the issue you mentioned while doing that.
And while my installed Q10 base is above ground, after you pointing it out, I see that was lucky, rather than smart :)
I had intended to use mine in my Progressive, but have decided that rather than fix something that isn't broke, and after getting some great ideas from Allison, it will go in a new single band (til I get 40 meters working well) single conversion receiver, which at the moment is looking like a QRPLabs VFO, into a not yet arrived SV1AFN FSA3157 H-Mode mixer module kit, plus or minus appropriate level/filter/matching issues..  I'm very curious to see how that compares to a Progressive in contest conditions.
Thanks very much again for, I know there are at least a couple other guys on here that will be happily looking over their boards in earnest after seeing your comprehensive list. 
And if I ever find a source for a good, through hole plated board I'll let you know for sure, as I would like a couple too.
73 Scott ka9p
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14711 2018-05-02 17:02:06 bellettau Re: FAR HyCas Circuit Board

HI All,

While I haven't built the HyCas board, I have built what appears to be a very, very close copy of it, except for the AGC section, by EI9GQ. [Eamon writes in Radcom and has a book "Building a Transceiver" published in 2015]

Eamon's IF strip is slightly different to the HyCas in that each stage is tuned and he uses a pair of JFETs in each stage.  The upper JFET could easily be replaced with an NPN transistor and the stages could be untuned and it would be near if not identical to the HyCas design. My build resulted in just under 70dB gain with AGC voltage at ~6v.

I built mine in two parts so i could modify if desired, the IF and the AGC section, both on 50x50mm PCB's initially home etched, then had a few made with plated through holes, made so i could incorporate them into my HF rig, old school crystal filter style. (using the eBay KVN 9MHz filters, currently available around for $30.)  AGC also based on work by EI9GQ.

I placed pictures and Sch details under my call in the files section for interest..


14757 2018-05-07 06:51:39 jim_amos_n8cah Re: FAR HyCas Circuit Board
Hi Glenn,

Thanks for the alternative IF design.  I'm wondering if you notice any difference in the AGC action?   Your circuit does offer multiple AGC settings, and also provides the S-Meter drive circuit.

I've developed an alternative layout for they HyCAS as part of an exercise to learn KiCad.   The first pass is done, but I did not preserve the reference designators.   I think I need to go back and update those to the original design to avoid confusion since the original reference designators are used from original documentation.  I did add SMA connectors as I'm using those on my board for easy measurement and connection to my test equipment.   I also used a transformer input circuit instead of the LC, but the board will accommodate either, but I do need to look at the footprint for the tuning cap.   I'm also considering doing a version in the original layout and posting as an alternative to the PCB express version.  But, I'll post what I have for feedback.

I was wondering if anyone else had any suggested modifications for component types used?    The input tuning capacitor comes to mind, and possibly the inductors.   But, my purpose is to generate some board files that can be used for buying boards off of Oshpark, and PCBWay.   I've priced my current board which is measuring 161mm x at $23 for 5, so that's pretty good for plated holes, silkscreen etc.


14770 2018-05-09 03:26:07 bellettau Re: FAR HyCas Circuit Board
Hi Jim, it's early days actually in my testing. AGC appears to work well, but that's just an audible test, no actual measurements made.   Since I made my mine 'modular' in that 2 50x50mm PCB's are used, then I can always change the AGC side if necessary. My project is still under construction. I have the Rx side running and now waiting for a couple of Chinese made PCB's to arrive, for Tx side of things.

On most of my boards i try to allow for various components to be used, so for the trim caps, if you look at the PCB (files area under VK3PE) you will see that I have allowed for several different types to be fitted.

I try to keep all my PCB's within the 100x100mm sweet spot for jlcpcb.com, allpcb.com etc. I think the HyCas pcb is larger than that.

14797 2018-05-14 21:19:35 zf2scka9p Re: FAR HyCas Circuit Board
Jim, that's exciting news.
As you mentioned about Glenn's post, it would handy if the S meter circuit from Wes' site was on the same board.
And it might be handy to have a few pads for an attenuator on the output so that the level is user configurable with extra junk offboard).
And as I recall a few of the ZOI boards had multiple holes in the trimmer cap areas so that no matter what you had, you could fit the trimmers of almost any configuration without too much difficulty.
Thanks, Scott 
(and thanks again for your list, after implementing your notes, I was able to quickly faithful reproduce the AGC curves and after trying it in the ZOI, am building a new receiver around the HyCas and wanting to do another HyCas for the ZOI :) 
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