Steve, N2CEI, over at DEMI discovered that if you place the BNC connectors for the IF-common and Reference port next to each other (generally what you would do since there’s already a hole in the panel), some 144 MHz RF may leak into the reference in on the apolLO board during TX only. This has the effect of producing spurs every x kHz where x is the modulus of the phase detector update frequency and the TX frequency. Essentially, at 144.1 on most transverters this would be every 100kHz. To fix this, all apolLO-32’s have been modified with an input LPF and all subsequent boards will have this mod on the board. If you have already purchased a board and the LPF is not present, drop me a note (apollo at n5ac dot com) and I’ll send you a retrofit kit to mod the board. If you use low drive level (10mW or so) this may not even be a problem for you. The 2W drive guys will have a problem, though. Also if you want me to mod your board, I’d be happy to do that if you want to ship it back here.
I’ll put up the mod instructions later today.
ApolLO-32 boards have now been tested and are shipping from us as well as from DEMI. We have stock to fill all orders with about 10 left over so everyone that has ordered one so far should receive it as soon as we can get the boxes stuffed!
Just a quick funny story too — my daughter, Jen, is helping me test the boards. We are modifying all boards with an input LPF to keep 144/432 MHz out of the reference port on the synthesizer (see next post). After I do this, Jen programs the boards and tests them on four key frequencies. Well the assembly house got a component in backwards … a tantalum capacitor. Many of you may know what happens when one of these guys goes in backwards, but for those of you that don’t know it is real exciting. She put the board in and flipped the switch. There was a loud pop and when I looked up there was orange-red flame shooting out of the top of the cap. Jen had this horrified look on her face. We laughed about it after I explained that it was the assembly house’s fault and it was no big deal. Welcome to the world of capacitors!
I’ve added the apolLO-32 docs to the documentation page here
It had become evident that I was going to have a hard time testing 100 apolLO-32 PCBs in short order without a test fixture. Mechanical wiz Greg Jurrens (WDØACD) suggested that I build a test fixture with spring loaded pins, guide pins, etc. which all sounded great except I had no clue how to do it. Greg volunteered to help me after I twisted his arm. I made a speed run down to Austin yesterday and he masterfully created the device you see below. I still have to add some switches and bolt the thing together, but it connects pads/pins on the board to connections for power and test by locking the board in the fixture. It’s a wonderful thing. I should have it finished in the next day or so and begin testing boards so I can send them out. Thanks for your patience!
The silver “pins” are guide pins made from 6×32 all-thread filed off at one end (it’s not pretty but who has guide pins in their junk box?). The gold pins are spring loaded test pins that either get soldered on the bottom (power, ground, etc) or have a connector put on them (programming cable for example). Wiring goes between the two polyethylene sheets. There are 15 spring-loaded pins in the jig, but you can’t see them all because they are in-line with the camera. You may recognize the standard “what have I gotten myself into” look on Greg’s face on the right.
I just received the first batch of 100 assembled apolLO-32 boards back from the assembly house. I’ll be testing them and filling orders shortly. A batch will also head out to DEMI for use in their products and for folks that have ordered from DEMI. For those that have already placed orders for the apolLO-32 directly from me, your orders will be shipped out by the end of the week next week (8/29) provided testing goes as planned. Everyone that has ordered a board will get a board and a retrofit kit parts (blue LED, BNC connector, instructions) also.