Friday, February 20, 2015

HF Upconverter - Assembly and Initial Testing


After a few days or working on my new HF Upconverter I got it working!  I'd been waiting for some Buck type DC-DC converters.  So I could connect the OCXO (3.3vdc) up to the 13.8vdc from my primary Astron RS-35M.  One of the Buck converters drops 13.8vdc to 12.0 vdc, then a second one drops it again from 12vdc to 3.3vdc.  They seem to be working fine.  The 12vdc is variable.  The 3.3vdc is not which is kind of a bummer, but it's at idle on my Fluke meter 3.29vdc. (probably close enough although if I'm going to the trouble of an OCXO I'd like the PS's to be adjustable).  I'll probably hunt around for a Buck DC-DC 12-3.3vdc that is adjustable.  These things are CHEAP on ebay.  Total spent on both was around $15.00 combined including shipping.  Which beats spending hours building them at this point.

I am running the OCXO HF upconverter right now as I type this, and it seems to be rock solid so far.  No FM Bcast interference (which I didn't think I'd have with all the shielding).

I have a fair amount of work to do yet on this.  However, the fact that the SBL-1+ Mixer and the OCXO work as expected is definitely encouraging.

I am listening right now to 14 Mhz Morse Code on the FTDX-5000 and also on SDR# at 109 Mhz.  (remember the FTDX-5000 uses a 9Mhz IF Output that I'm tapped into, so the actual VFO frequency is irrelevant since all signals are sent out in the 9 Mhz realm.

Anyway...I just wanted to post that as simple as this is right now and working as well as it is, I can't wait to add the Lo and Hi pass filters to my Homebrew HF Upconverter that is accurate to within 200ppb (that's parts per BILLION)!  NO DRIFTING has been noted in my testing thus far.

Tomorrow I'll start it up from cold, and see if there is any noticeable.  I'll also post some updated pictures of where the project is now.

Things are subject to change until I setting on a mixer.  While the SBL-1+ works fine I'm curious how well the the other two I ordered from Minicircuits will work.  The are supposed to be better, and certainly should be at 4-7x the cost of the SBL-1+ (which was only $9.95).

This is FUN STUFF!

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