N5AC

OK1DFC has completed his 2.3GHz EME transverter built on a N5AC A32 Synthesizer board and a DEMI 2.3GHz transverter.  The completed transverter allows for cross-band T/R in any of the four international 2.3GHz subbands with a single synthesizer board.  Check it out here:

OK1DFC Crossband transverter

Steve

I’ve been commuting to Austin (from Dallas– 200 miles) for about a year now with my job and it was getting old so we decided to move the whole family down to Austin.  I’ve been a little slow shipping orders the last couple months because we’ve been packing up the house and getting moved.  The new lab is all set up now and I’m back to processing orders as they arrive.  If you’ve ordered something recently, it should be shipped in the next couple of days.  Thanks for your patience.  Our new address is:

9001 Full Moon Cv
Round Rock, TX 78681

The original apolLO I driver was built several years ago and only had support for 32-bit operating systems and has not been tested to any extent on Vista.  We have recently added 64-bit support and support for Vista with a new driver for the apolLO I USB-programmable oscillator.  This driver should download automatically if you are connected to the Internet.  If you are not being prompted to update your driver, you may also manually download it here as a ZIP file or here as an ISO file.

I have recently seen two situations where an apolLO I fails to lock, but does not appear to have a hardware issue.  Upon investigation, I discovered that the EEPROM where the setup is stored (frequency, etc) has been overwritten in the first location.  Specifically it has a 0xFF instead of an 0×23 in it.  I am not currently check-summing the values or performing any other checks and so it causes bad data to get loaded into the synthesizer.  This occurs for firmware 1.15 and earlier.  I have updated the software to check to ensure that if a 0xFF is found, it is replaced with a valid 0×23.  This is a temporary fix until I can find the root of the problem

I have not seen any other cases of this, but this could be because others assume they have damaged the board, etc.  If you have a no-lock situation when you believe it should be locking and have made sure that it is not your 10MHz reference and a valid frequency/PFD (R and N) are in the board and would like to check for this problem, you have a couple of options:

1) If you have access to a Microchip programmer, you can check the first EEPROM location (0) and verify that it has a valid value.  If it does not, you can reset the board to a factory state by writing 23 0D 70 04 00 00 00 0A 00 00 00 40 into the EEPROM starting at location (0).  Be sure to read the entire program, view the EEPROM, update it and then perform a program.  If you do not read the entire contents of the part first, you can write an empty program back into the part!

2) You can return to board to us and we will rewrite both the EEPROM and the updated software into the part and return the board to you.

If you have any questions, please feel free to drop me an email.  Note that the apolLO-32 does not use the EEPROM and therefore cannot have this problem.  All values are hard-coded in the software in the apolLO-32.

73/Steve

Several new apolLO-32 frequencies were added in the latest revision of the software, C5.  The majority were for international (non-US) allocations including the 10,450MHz band in Japan.  Details can be found in the frequency list here

DEMI has just unveiled their new WSSA-M tunable Weak Signal Source based on the apolLO-32.  Previously, to get a weak signal source it was necessary to buy one per band.  This new DEMI product built on the apolLO-32 has a rotary switch allowing you to select up to five of the preprogrammed apolLO-32 frequencies.  There is also an internal option to use a on-board TCXO for a completely self-contained signal source.  The frequency list is available in the documents section of our website here.

Details on this and the other weak signal sources from DEMI can be found on their website and in this flyer:

http://www.downeastmicrowave.com/PDF/wssA32_pd.PDF

DEMI WSSA-M Weak Signal Source

The unnamed dish pointer project won a 2nd place finish in the annual SVHFS design contest last weekend.  The dish pointer has a 3-axis accelerometer and compass for sensing the absolute position of a dish as well as a pair of H-Bridge drivers to run linear actuators.  An LCD shows the position of the dish and has the menu lines for the buttons (not shown).  The sensor/drive mechanism are separated from the control by a pair of Ethernet cables.  I’ll be working on this guy for the next few weeks and I’ll put some more info up here when the software is more complete.  Stay tuned!

Dish pointer hardware

The website was displaying some PHP junk from sometime on Saturday 4/25 through this morning.  It was caused by an error in the vendor we use for a shopping cart and it crops up from time to time.  FYI, we use the shopping cart simply to prepare an order for products and then we transfer the order to Google Checkout.  Google is responsible for collecting payments and we never touch the actual payment information.  I have run a full-up ecommerce site before when I owned another business and it was routinely the target of hacks.  None were successful, but I did spend considerable time monitoring it and with someone else to do it for a small fee (Google), it was just the right way to go.  It allows me to focus on electronics and you know your card information is safe with the big boys.

Several requests for additional frequencies have been made since the apolLO-32 first shipped with 32 frequencies pre-programmed.  While some have opted to get an apolLO-I and program in their particular needed frequency, some would still prefer the convenience of a pre-programmed set of frequencies.  For the revision C board, an additional 3 jumpers were added increasing the number of pre-programmed frequencies to 256 (yes, we could rename it the A256, but seems a little silly at this point!).  And with the additional space, I’ve been busy adding additional frequencies.  Some of these are for international amateur allocations and others are for somewhat unusual IF frequencies.  

If you intend to use an A32 in a fairly typical IF/RF combination for your particular country, I will gladly add the requested frequency to the pre-programmed set.  For a specific frequency for a beacon, say, it probably makes more sense to use an apolLO I where an arbitrary frequency can be programmed. 

Here’s the list of recently added frequencies for Rev C2: 902.1, 1275, 1420, 1152, 1128, 1116, 1268 and for Rev C3: 1151, 1077.5, 1078, 1127.5, 1022.3, 1022.4, 1149, 1267, 1276.  No frequencies are deleted and so you just need to ensure that the revision of the board you are using is at least the revision specified to have that frequency.  The testing sticker (pictured) will show the specific board revision for all revisions C2 and after.  If the revision of the board is important to your application, be sure to ask for a specific minimum revision when you order from us or DEMI.

The list of frequencies can be found here: apolLO-32 Strap Positions.

A32 Revision Sticker

Jim, WD5IYT, and I went roving in January again (last week) and had a blast.  We were QRV from 6m-24GHz (11 bands).  One interesting thing that happened a couple of times was a step-function shift in audio on received signals on a few bands.  Unfortunately I do not have a recording of this, but imagine if you have a VFO that tunes in 100Hz steps and when you are listening on sideband, you just click the knob a few times.  This was also heard on my transmit signal.  Apparently, RF is getting into my GPSDO — an HP 58540a (400W of 2m no doubt) and causing it to either reset or get confused about where it is.  It always quickly recovered, but this underscores the need for some shielding on the 10MHz lines running around if they will be exposed to a high-RF environment.