In the 6ish years I've been a ham I have not once touched or operated on 60 meters. It is the only HF band that is unexplored territory for me. That being said, 60 meters may be unappealing to many hams as it was for me. You're only limited to 5 channels with 2.8KHz of bandwidth, mode choices of SSB, narrow data modes such as PSK31 or CW, and a maximum power limit of 100 watts ERP. Not very appealing :|
However...we have a lot to work with here, given the little bit of real estate we have on this "Rock Band." CW has a bandwidth of a few hundred hertz, whereas a single channel on 60 has 2,800 Hz of bandwidth. This means that many CW QSOs can occur on the same channel at one time, right?
Wrong.
CW communication MUST take place ON the center frequencies, listed below. So, no, you cannot move around within the 2.8KHz window. Still kinda stinky...
Many 60 meter operators are also QRP and many more run QRPp levels. 60 meter crystals are also not hard to come by, and in fact, one Czech operator I believe was practically giving some away for free (minus about $2 shipping) to encourage more 60 meter operations.
Well that's much more appealing now, let's get started!
The Project
Yeah, I'm going to use a Pixie. But why use such a simple and quaint circuit?
For starters, the Pixie comes stock for 40 meter operations, or 7MHz. 60 meters is slightly below, at around 5.2 or 5.3MHz. The only thing we need to change in this circuit is...well, nothing (that is, if you want to leave the stock LPF). Yes, that's right. The only thing we need to change is our crystal, and bam - we're on 60 meters! Remember, we ARE devised into channels, so 60 meters is perfect for rockbound operations!
Great! Wonderful! The End.
...or maybe not.
Further Mods
Because it's not a true Pixie without any modifications.
Since 60 meters is channelized, we can literally install a crystal switch to switch between only two frequencies or all five, however you want to configure it. A simple SPDT switch will work great for two crystals. Here is an example schematic:
I will more than likely produce PCBs for this circuit so stay tuned! These would also work well with other QRP circuits too such as the Ten Minute Transmitter.
Not too difficult and just 4 components. As for tuning - no need. 60 meters is channelized for a reason, just use the on-board pot for fine tuning :)
Next, we'll need to refine the low pass filter. If anything, I highly recommend using a band pass filter instead of the included low pass. Kanga kits has an excellent write-up that discusses how to construct a very effective one with components you already have.
Why 60 meters suddenly?
It's an underutilized band. No, seriously, it is.
60 meters is excellent for NVIS during the daytime. A dipole for 60 meters is about 87 or 88 feet in total, so not too much space. In addition, with a simple fixed-frequency QRP kit like a Pixie, 60 meters fits the bill tenfold.
Recently, I've been scouting around on WebSDRs and I have been listening to all 5 channels of 60 meters. Channel 3 appears to be sporadically filled with FT8 from time to time (I strongly recommend AGAINST using FT8 on 60m period), channels 4 and 5 both appear to be used on a regular basis for both CW and SSB. Channel 5 is a DX channel by de facto, and while DX isn't necessarily impossible for QRP, it may or may not be feasible.
The main reason us hams don't get a wide array of bandwidth is because of the National Telecommunications and Information Administration (NTIA), which is a governmental entity. Concerns were raised very late in the FCC's deliberation of allocating 60 meters about possible interference. It has also been loosely suggested that the US Armed Forces use 60 meters heavily. Us hams are known as domestic and secondary consumers, meaning that we are limited to domestic use on a secondary basis. All ham traffic should yield to traffic that has primary privileges on these frequencies.
In a nutshell, if you are told to stop transmitting - STOP TRANSMITTING!!!
Channel 1: 5332KHz
Channel 2: 5348KHz
Channel 3: 5358.5KHz
Channel 4: 5373KHz
Channel 5: 5405KHz
For CW (Designator 150HA1A) operations, you MUST tune your radio to these frequencies. CW has a bandwidth, as mentioned previously, of <150Hz, and while this is narrow, it is imperative that you tune your radio to these specific frequencies.
On special occasions, the military will allow QSOs to occur between Armed Forces stations and amateur radio stations, furthering and strengthening the bonds between the ham community and the men and women defending and protecting this country from threats, both foreign and domestic.
Sourcing Crystals
Crystals for the 60 meter band, namely Channels 4 and 5, can be found on KC9ON/3rd Planet Solar's website. They only come in HC49/S packages but these will work perfect with the Pixies. These crystals are sold at about 25 cents a piece - go get you some!!!
Of course if you can't source crystals, you can use the Si5351 method that I discussed in a previous post. Feed the 5351's output into the amplifier transistor's base via a decoupling capacitor and remove the entirety of the oscillator section. See the post for more information.
Pixies are down to about $3 to $4 on AliExpress with FREE shipping right now. Go grab several and get to experimenting!
No comments:
Post a Comment