Saturday, April 17, 2010

Off Topic: Acer Aspire One 110L HDD mod

I went out in order to buy stuff... what I came back with was a 30GB USB-HDD called LaCie Little Disk. When I connected it to a PC, the hardware recognition reported a Samsung HU030HA disk. Ah! That calls for google ... this and this came up. I am actually able to read both, Italian and Dutch.
It all comes down to pulling the ZIF cable from the drive and insert it (same end) the other way around.

Here's what the drive looks alike, the ZIF cable is already turned.

Now lets have a look at the open Aspire One 110L. The SSD is still in place. In order to remove it, the right hand side I/O PCB need to be removed, since the SSD's second holding screw is hidden below this PCB.

Now, with the HU030HA installed, just before the I/O PCB was reinserted.

This is what you have been waiting for:
$ sudo hdparm -t /dev/sda

 Timing buffered disk reads:   56 MB in  3.02 seconds =  18.53 MB/sec

BTW, my Aspire One is running Jolicloud. Was it worth building in the HDD? I don't know yet. The netbook feels somewhat more responsive, mass-storage is increased from 8GB to 30GB and there is no need to be afraid of too many write cycles...

Wednesday, April 14, 2010

IBP Beacon Superhet-RX XTALs

IBP beacons are nice and easy propagation indicators. With dedicated single frequency receivers, a nice propagation alert system could be built. Basic idea here, detect Morse-code and signal strength by means of micro-controllers, transfer this information to a PC and upload it to a web-page (e.g. grabber).

For coverage of all bands, 5 receivers would be required. Again I was thinking of the N3ZI boards, which would need pairs of crystals. Some back and forth thinking and looking at numbers, I was able to find pairs of well available crystal pairs. The suggested IF would be represented by the lower frequency (better ladder-filter) or cheaper crystal.
This is what I came up with: (suggested IF / suggested LO)

20m (14.100MHz)
  • 4.096MHz + 10.000MHz
  • 2.097MHz + 12.000MHz

17m (18.110MHz)
  • 8.000MHz + 10.106MHz

15m (21.150MHz)
  • 6.144MHz + 15.000MHz
  • 8.867MHz + 12.288MHz

12m (24.930MHz)
  • 14.746MHz + 10.180MHz (*)

10m (28.200MHz)
  • 4.194MHz + 24.000MHz

(*) 10.180MHz is a crystal found in 22 channel CB-radios.

Now, lets hope that the PCBs are a success, and a fully automatic propagation alert system will welcome the upcoming solar cycle.

    Ceramic Resonators for VFO use

    Not only crystals make suitable LOs, VXOs or super-VXOs, there are also VFOs designed with ceramic resonators. VFOs with ceramic resonators are not stable enough for QRSS or WSPR, however, CW or SSB do not require the same VFO stability as the digital mode.

    Some resonator frequencies (MHz) I know about:
    • 2.00
    • 3.58
    • 4.00, 4.03, 4.16, 4.19, 4.50, 4.91
    • 5.00, 5.50, 5.74
    • 6.00, 6.50
    • 8.00, 8.64
    • 10.00, 10.70
    • 12.00
    • 16.00
    In combination with some crystals, those resonators would make some awesome VFOs.

      Tuesday, April 13, 2010

      Universal NE612 PCB

      N3ZI offers nice little PCBs (click here) for superhet receivers.
      It appears that those little receivers can easily be turned into transmitters. I got some ideas in my mind, which I will successively add to this post, so, stay tuned.

      For a 10MHz I.F. and a crystal controlled LO, please see my earlier post. For QRSS I would favor 7000800Hz, 14000800Hz, 21000800Hz and 28000800Hz, since crystals (oscillators) are available for 3MHz, 4MHz, 11MHz and 18MHz.
      More cheap crystal combinations could be found on my web-page. Note that only pairs with M=1 are "drop in" compatible with N3ZI's PCBs.
      One nice option appears to be a dedicated 17m WSPR receiver, or maybe even a transceiver. This design would make use of a 8.000MHz I.F. and a 10.106MHz crystal (30m QRP). A tiny bit of pull and the carrier frequency should be 18.1046MHz.

      600m is easily available with the following crystals: 5.000MHz - 4.5000MHz - 4.000MHz - 3.500MHz - 3.000MHz - 2.500MHz - 2.000MHz.
      Remember, the subtractive mixing product compensates for thermal drift of the oscillators.

      Transmit?? you may ask yourself... Yes, I believe that Douglas' PCBs are equally suitable for generating a single side band signal. Please have a look to the schematics on N3ZI's webpage.
      A modification to a transmitter, in my view, could be the following:
      1. feeding an AF signal to pin 1 of U1, the input filter and transformer make place for an AF network
      2. X6 should have the same frequency as the filter-crystals
      3. U2 is now a converter, thus, X5 serves the LO
      4. Q2 a buffer, C17 should therefore be replaced by a some means for linearizing Q2
      5. C22's capacitance should definitely be reduced
      I figure that this PCB, modified for transmit, together with a simple MP3-player, makes an excellent base for a MEPT in combination.

        Two PCBs will provide a nice and easy transceiver. One PCB just like intended, the other modified for transmit as shown above. Here, some additional considerations seem appropriate:
        1. feed the BFO from the RX board to U1 of the TX board, alternatively use an external BFO
        2. feed the LO from the RX board to U2 of the TX board, alternatively use an external LO or VFO

        As soon as I got the first results, I will write an update on this site. Stay tuned....

          Monday, April 12, 2010

          10.000MHz I.F. Superhet Crystal Combinations

          Employing a 10MHz I.F., some options for a cheap and simple crystal controlled LO could be:

          • 3.599900 = 10.000 - 6.400
          • 7.000800 = 10.000 - 3.000
          • 14.000800 = 10.000 + 4.000
          • 21.000800 = 10.000 + 11.000
          • 28.000800 = 10.000 + 18.000

          • 14.0956 = 10.000 + 4.096

          • 13.560 = 10.000 + 3.560

          • 5.000 = 10.000 - 15.000 (WWV)
          • 14.194 = 10.000 + 4.194 (SSB)
          • 15.000 = 10.000 + 5.000 (WWV)
          • 21.060 = 10.000 + 11.059 (QRP)
          • 28.432 = 10.000 + 18.432 (SSB)

          • 20.100 = 10.000 + 10.106 (Radio Jove) 

          Ceramic resonators
          Ceramic resonators can be pulled further and more easily. This results in less stable VFOs which will be good for CW and SSB. They could be stable enough for some digital modes such as PSK. They will certainly not be suitable for QRSS, WSPR, etc.
          • 10.000 - 6.50 = 3.500
          • 10.000 + 4.00 = 14.000
          • 10.000 + 4.03 = 14.030
          • 10.000 + 4.16 = 14.160
          • 10.000 + 4.19 = 14.190

          Maybe there are more combinations available. Please let me know. I will update this list as soon as there is more...

          Ten Tec SCOUT/ARGO Modules for 600m?

          Having both radios, the Ten Tec SCOUT 555, for more than 10 yrs by now, and the ARGO 556 ( = SCOUT w/o the P.A.) which I was lucky to obtain some months ago, a thought came to me if the transceivers modules could be modified for 500kHz or even 136kHz.

          In principle nothing should speak against this. The SCOUT uses an I.F. of 6.144, the L.O. is generated by a 2.2MHz PTO signal, mixed to and by a NE612 XO/mixer in the band modules.
          For 80m that means: 7.444 (XO) + 2.2 (PTO) - 6.144 (I.F.) = 3.500 (QRG)
          This would mean for 500kHz: 4.444 (XO) + 2.2 (PTO) - 6.144 (I.F.) = 0.500 (QRG)
          It would be necessary not only to replace the crystal but also the LO filter network.
          The 160m module can be tuned to about 1.5MHz, however, the PTO stabilizing aka FLS (frequency lock system) does not lock in anymore, Ten-Tec mention here that the AM band rejection  in the 160m module would be causing this.

          Since the modules also carry the band filter, it seems that no modification to the radio itself is required.

          Now we've seen that 4.444MHz is the highest usable local oscillator frequency. So, what crystal will be available and where would the lower band edge will be?
          • 4.433MHz => 489kHz
          • 4.194MHz => 250kHz
          • 4.096MHz => 152kHz
          • 4.000MHz => 56kHz
          The PTO has a range of 500kHz from the lower band edge, so all the above standart frequencies will cover the 600m band.

          Saturday, April 10, 2010

          WARC bands - WSPR/QRSS Crystals

          OK, 30m is trivial, so let's forget about that for a moment.
          What about 17m and 12m?

          For 17m I found a very suitable combination:
          • 13.104MHz + 5MHz = 18.104MHz
          Some upwards pull by 600Hz, and we are there. Personally, I would build the filter(s) from 5MHz crystals, the pulled XO would therefore be at 13.104MHz. Both crystals are available from Pollin (

          12m will be somewhat more tricky:
          • 16.9344MHz + 8.000MHz = 24.9344MHz
          Here, a downwards pull by 9.8kHz is required to reach the WSPR band, that is a lot. However, it should be doable with the 16.9344MHz crystal, which would therefore serve as XO while the 8MHz crystals will form filters. Those crystals are also available at Pollin.

          Just as a quick reminder, there is nothing wrong with operating QRSS next to WSPR.