Group Buy Transverter FAQ
Well, honestly, they may not be "frequently asked", but we're trying to provide as much information for everyone as possible on this page. If you do not find your question answered, ask! And if you disagree with any answer, feel free to discuss.
Group Buy Questions
Which LO (local oscillator) goes with what transverter?
902/903 MHz transverter - 756 MHz LO
1296 USD (upside down) transverter - 720 MHz LO
1296 RSU (right side up) transverter - 1152 MHz LO
2304 MHz transverter - 720 MHz LO
3456 MHz transverter - 720 MHz LO
What's all this USD and RSU stuff?
The upside down and right side up refers to the tuning of your i.f. (intermediate frequency) receiver or transceiver. Using the 1152 MHz LO with the 1296 RSU transverter board yields 1296.0 at 144.0, 1296.1 at 144.1, and so on. If the 720 MHz LO is used, its frequency is doubled to 1440 and therefore 1296.0 is tuned in at 144.0, but 1296.1 is tuned in at 143.9 MHz. Note that some 2-meter transceivers may not tune or transmit below 144.0 MHz. The only reason to use the 1296 USD is to take advantage of using the 720 MHz. LO for multiple bands.
Any kind of guarantee?
Nope! We are just conducting a mutually advantageous group buy of parts. You are on your own, but keep in mind that the "group" is here to help you -- and we do have some rather technically adept experts among the group.
Will the group buy be repeated?
At this point in time, it is very doubtful unless someone else would like to volunteer for another.
Missing parts, lost parts, ruined parts
Of course, if you find a part missing when you receive your order, just email us. With the surface mount very small parts such as capacitors and resistors, if you manage to mangle one or send it off into the wild blue yonder, we'll have a limited supply of extras so an email and SASE will bring you a replacement.
What are the most popular bands?
Of course that depends on your location, but generally the four bands we are considering are, in their order of popularity, 1296, 2304, 902, 3456.
General Technical Questions
How difficult is construction?
First, read W1GHZ's conference paper on the transverters. Yes, they do use the little bitty surface mount (SMT) parts which do require some different skills than putting together "through-hole" parts or tube rigs. Nearly all hams, who are daring enough to actually try SMT, do well and many strongly prefer that type of construction after trying it. There are loads of tutorials on the web, including YouTube, on how to perform SMT soldering. Some hints: good lighting, magnifiers, flux, thin solder, small soldering iron tip, practice. Our parts will be 0805 and 1206 sizes. If you don't know SMT, we suggest you get some practice in on other simple kits first. If you are still uncomfortable with doing SMT work, you should be able to find some willing ham nearby who would do it for you. There are really not that many parts to each board. Since we are not supplying complete kits (ala Heathkit style), you will need to complete them with your choice of connectors and enclosure along with such things as the 8 volt regulator, any power reducing pads, etc.
What is the IF (intermediate frequency)?
Generally a 2-meter transceiver (or separate transmitter and receiver) is used. The 1296 USD version requires tuning below 144 MHz for frequencies above 1296.0 MHz.
How good is frequency calibration?
Fairly good, but it is dependent on your canned crystal oscillator used in your LO board. There is no provision for adjusting these can type oscillators, so the user must correlate actual frequency on his transceiver.
How much drive power is needed on 2-meters?
About 1 milliwatt ( 0 dBm ) maximum is required. Use caution not to exceed this amount!
Can these transverters be used with the DSP-10?
Yes, it appears a very good match! (That's my plan --AE5K) For those wondering what a DSP-10 is, it was featured in a 3-part article in QST in the fall of 1999 (wow, that long ago?) by W7PUA. http://www.proaxis.com/~boblark/dsp10.htm
The DSP-10 puts out usually better than 10 dBm, so a resistive pad is in order.
Can they be used with small HT's (handi-talkies)?
Why not? Would make a nice rover station, but remember most HT's are only FM mode and most activity on the microwave bands take place using CW or SSB! Again, beware of pumping too much power into the transverter on transmit.
OK, what's a "rover" station?
One that is usually quite portable and is often used in microwave contests to give more grid contacts, or often in a non-contest situation it could be a station located on mountaintops or other good operating sites. Due to antennas used, a rover station is most often not mobile (transmitting while in motion), although some hams have that capability.
Is there a problem using transceivers with their power adjusted down?
With many commercial transceivers, there is a potential problem with them putting out full power when first being keyed up and before their AGC takes control. This produces a spike that may kill the first stage in your transverter. The most foolproof method of making sure you have the very low power needed is to use a resistive pad -- but then that complicates things since the pad provides the same dB loss on receive also if left in the pathway, so usually some relay switching arrangement is used then.
What modes can be used? AM, SSB, FM, etc.?
Interesting question! All can be used, but we run into "band plan" problems. You could cause some concern with other operators by using FM on 1296.1 MHz for instance. Check out common usage of the band you are operating in and be considerate. These transverters don't put out much power by themselves, but with the right antenna and right location they have capability of communication and interference, especially in more populated areas.
How do these transverters compare with DEMI and DB6NT
These are meant to be "cheap and simple" and were originally designed for rover type operations. They are certainly not toys and you can expect good performance, but let's face it, they are NOT as good as the much more expensive and fine products offered by DEMI (Down East Microwave) or DB6NT. They will get you on the air and could provide much enjoyment with a proper antenna. Their performance should be able to be enhanced with additions of low-noise pre-amp, more filters, and power amplifiers. The author makes the strong suggestion of using additional filters when used with a power amplifier. Since they are so "cheap and simple" as Paul W1GHZ puts it, many will buy and build two to have an extra to loan out or as a spare.
Are there any other groups/organizations for microwave?
One of the very best conferences for microwave devotees is called MUD or Microwave Update and is held annually at various locations. Next one coming up is in October 2009 and is being held in Dallas, Texas and hosted by the North Texas Microwave Society (NTMS). http://microwaveupdate.org/ The NTMS is also a good organization, especially for those in the DFW region. http://www.ntms.org/ We in the 4-State Microwave group are trying to encourage more activity in our area (Arkansas-Kansas-Missouri-Oklahoma) and adjoining regions.
Can you suggest other options for IF transceiver?
The Yaesu FT-817 is a popular low powered and compact all-mode transceiver. Here's a website that will give you some information: http://www.ussc.com/~turner/ft817pg.shtml
Here's one more from Art, KY1K: "You and your group MIGHT want to be aware of Dave, WB6HDW's DC to 900 MHz transceiver, which is an SDR. http://wb6dhw.com/ It has good receive sensitivity and puts out 100 milliwatts. It costs under $200 to build, which is a little pricey, but half of that price is the low phase noise LO. Right now, it needs a computer sound card to operate. But, for a single op station that has a computer anyway, or for a rover, the rig should have allot of appeal. It sure beats the heck out of spending $1000 or more just for an IF radio! It is in development now, but the beta builders pointed out some needed changes, so it will possibly go through another limited production run. They are of course available as a kit, I sell the kits. But there is no obligation for anyone to buy my kit and the PCB is public domain for those who want to order their own."
What about "sequencing" -- is it needed?
Yes! We'll have more on our web pages soon on this. Meanwhile we would encourage discussion on the 4smicrowave reflector on this topic. (Sequencing means you need to switch your antenna relay from receive to transmit before the transmitter transmits and not release it until the transmitter has stopped putting out RF -- else bad things happen!)
2304 & 3456 MHz Transverters
What about the pipe caps?
These are not supplied in the group buy since they should be readily obtainable at hardware stores or places like Home Depot, Lowe's, Menards, etc. Prices have gone way up on these as copper prices have risen. I was able to save some money by playing the "low price guarantee minus 10%" game with Home Depot vs. Lowe's ;-) My mother, a real penny pincher, would have been proud of me!
What about the 5 volt requirement?
Yes, the 2304 and 3456 use +5 for the first MMIC stage. Maybe a solution is to use a TO-220 type 7805 in the 720 LO board and get power from there? More on this later.
Copyright © 2009, AE5K - Modified on 2009-Mar-23