Eggbeater II (2)

Wow, that was easy. Nailed it all together. Actually, even though I found some RG62, without the delay line (some call that thing phasing), thus, linearly it will be polarized for now.The whole is mounted to a 40mm PVC pipe. No surprise here.

The surprise came when hooking it up the the MFJ analyzer. The SWR shows a minimum of 1.1:1, and, that actually takes place at 435MHz! K5OE did not promise too much. BTW, with AOL services closed, I hope Jerry's original page will show up again somewhere else.

Now that the standby RX-aerial is done, part two of the exercise will probably be to build TPMs (Texas Potato Masher) to be placed on a cheapoe rotator for TX.

The first setup is now more or less completed. Shopping for more PVC plumbing done.

Finally, I decided to leave in aerial linearly polarized. When remembering correctly, the difference would be 3dB. OK, this could make or break the link-budget, but than, this is supposed to be the first setup of its' kind that I made... collecting experience is a part of the game, I figure.

Now, lets wait for the first signals to appear!

UHF Eggbeater II

Having had the FT-736R inactive for sooooo looooong, it's time to think about putting together some aerials for space communications.

In the past I looked into the subject-matter before, but never actually found time and space to set things up. Thus faintly, my walnut recalled something called "The Eggbeater" and "The Eggbeater II", both, to me, are variants of the famous Turnstile. Some zick-zack thinking resulted in the decision to build an Eggbeater II for 70cm. Actually, I bought the material for the VHF version too.

If you are now puzzled what I am talking about, click here.

Here in Europe, we usually talk metric. The closest equivalent to #10 (AWG I assumed) copper wire I could find in my local hardware store was 6mm² copper wire.

The result, so far, can be seen in the image below. Bits and pieces still have to be assembled on a PVC pole. Before doing this, however, I first intend to test the aerial with both linear and RHC polarization.

ahh!

Now we are getting somewhere. Frequency for the subharmonic L.O. reached. I actually got two parameters to play with for frequency adjustment, the capacitor in series with the crystal and the supply voltage of the ocillator. This is actually adjusted and measured at 5V. Oscillation stops at about 4V. The circuit itself however, is designed for stabilized 8V. Thus, here are some degrees of freedom for the final tuneup.

As a last resort, I blamed it on the crystal, as suspected before. The crystal I used in the first attempt was not good, as shown by the replacement which more of less on the spot produced the correct frequency. Ouf! I need to build myself a crystal tester, I guess. Could possibly spare me some sleepless nights ;-)

The signal itself is not that perfect yet. I will have to install some resonating filter, I guess, to smooth out those humps and bumps to something that comes closer to a sine-wave than that...

Finally, the Poliakov-type mixer works best with a well balanced sine-wave.

Oh, and if you are interested in what I actually used for transistor, it's a 2N2222A. The rest of the bits and pieces are somewhat obvious and not worth to be mentioned individually...

hä?!

No matter what xtal-oscillator I build, it allways oscillates by far too high.

Now, with a huge amount of inductivity I got my 5068.8kc crystal pulled "down" to just below 5070kc.... I don't get it! I remember times, when I did not manage to pull a crystal above it's nominal frequency. OK, yes, I know the game about series and parallel resonance, and, when it unknown which one of printed on the device...

Back to experimentation, and maybe I will sort things about before going nuts!!

Photos of the E-probe

This aerial, or better electric-field probe, is now in successful use for quite a while (see earlier posts). The design is similar to the one by PA0RDT. To me, this is a very short Hertzian dipole with high Z front-end and a high gain pre-amplifier.

The whip is encased as the two photographs show. Yes, it's plumbing parts that for the enclosure... advantage: waterproof!

The active aerial is use in combination with a Target HF3/W receiver, which supplies 12V for active antennae on the flip of a switch, very handy! The receiver itself is certainly not the best ever made, however, the combination is unbeatable in ease of use for naval weather reports, FAX reception, NAVTEX , Volmet or broadcast reception.

plans for this evening....

Not having done anything other than QSOing, fun too, I admit, it's again time to wrestle solder. As starter, I will tackle the 30m-WSPR-TRX.

Since this will be a subharmonic design, I wanted to ensure a nice sine-signal for the diode pair. First plan, here, a slightly pulled up 5068.8kHz crystal in a Colpitts oscillator. Somewhat standard, isn't it? The aim is a super clean sine carrier with a frequency of 5069.35kHz. The pull would thus be a whopping 550Hz, that should be doable without any further issues.

Let's see how far I get, how stable it will be and if an oven should be added...

73 for now!

no progress

Sorry to write, but there has not been any progress on any of my projects lately. This must have something to do with all the parts that had been delivered lately ;-)
Honestly, this weekend was reserved for other activities... We will see about the upcoming weeks.

Open projects:

• the AXEmite
• 30m PSK-TRX
• 30m WSPR/QRSS-TRX
• long-wave generally
• TRX for maritime nets (20m)
  

Further in the planning (amongst others):

• combined QRSS RX for 80, 40 and 20
• dedicated QRSS RX for 22m
• NAVTEX RX (518kHz)
• propagation alert RX for 6m and 10m
• APRS TRX (old Taxi-radio)
  

If there only were more hours in one day...

today: xmas!

All my stuff came, all in one day, crystals, trimmers and the /p-antenna.

20,250.0kHz

Just bought 100 crystals having a frequency of 20,250.0kHz. Presently, I have a job for two of those only. Lets see what ideas pop up later...

BTW, the idea is to build a super VXO and divide it by two... NO, not the VXO, the frequency it generates ;-)

WSPR/QRSS transceivers

WSPR is fun, and not only, it make some sense, propagation phenomena can be looked at decently.
However, having the band of own WSPR activity blocked is bad enough, even worse, having a transceiver blocked...

For 30m-WSPR, Gene (W3PM,GM4YRE) made a nice design, check this out. Nice ideas, however, I would/will do one or the other thing in a different way. Nevertheless, the basic idea is to create a DSB-signal, with some sideband separation by a simple single crystal filter. My present design ideas will not fall short of digital ICs and probably something subharmonic...

For 20m however, another nice option is available with a combination of standard computer crystals for a superhet design.

With a carrier frequency of 14,095.6kHz, the obvious choice would be a 4,096kHz and a 10,000kHz crystal. Either one could serve as I.F. in a ladder-filter. However, I found some 4,068.5kHz crystals, thus, for my attempt, 10,000kHz will be the I.F., allowing for a second frequency suiting the 20m PSK31 range.

Additional option: add yet another crystal and be ready for the 20m QRSS band, yep, that would then be a 4,000kHz crystal.

The next building project is in the queue.

QRT for now, "back to the drawing board" if you want ;-)