Glen Overby, KC0IYT ([email protected]) wrote:
> 1a. How many surface-mounted components are on these boards? No,
> I haven't soldered any surface mount boards yet.
The 222-28 transverter has just a handful (about a half-dozen as I
recall), and I found them to be large enough to work on without any
special magnification. It was my first project ever that had any
surface mount components.
The 902-144 transverter I bought was supposed to be the CK (complete
kit) version, but due to a temporary problem with their supplier of
pre-tuned coils (they were tuned wrong by the supplier), DEM sent me
a "basic kit" which had the main PCB mostly assembled already, so that
they could do the alignmnent of the mis-tuned coils. There were only
a small number of surface mount components, but I would not have had
a problem getting it assembled if it had come as originally planned.
The 1296-144 unit I have was assembled at the factory and sold to me
used by another NLRS member. It is the older style, not what is now
being shipped, but it too would not have been hard to assemble.
I've looked at the assembly instructions for their 10 GHz transverter
kit and that was enough to scare me off. Just so you know that I don't
consider myself to be a 'fearless' kit builder. I grew up with various
Heathkits (oddly enough, NONE of them Amateur Radio related), and miss
those days. But the DEM assembly instructions are 'good enough'.
> 1b. Before I go with a kit, I'd like to know what "tweeking and
> tuning" is required to get the kit from components soldered to a
> board to a working transverter?
Assuming you have some assembly experience and do it correctly, the
tweaking and tuning is easy as can be. You can manage with a DVM.
Of course, if you mess something up, more tools are handy. For
example, I had my 220 handheld to test out the 222 transverter and
it came in handy. I actually did use my oscilloscope to try to
troubleshoot a problem of zero measurable power coming out of the
222 transverter, but in the end, the instrument that made all the
difference was the one between my ears. (Hmm, zero power output
measured, but the heat sink is getting real hot. I wonder if the
jumper cable from the transverter to the power meter is bad? Yep,
dead short!) I also did use a cheap Radio Shack frequency counter
to tweak the oscillator a bit, but if you have a receiver that can
operate on the band you are building, that could serve as an
adequate way to insure you're tuned where you think.
> My test equipment currently includes a 35mhz oscilliscope, and
> 2m/1.5m/70cm SWR meter. I doubt that is adequate for tuning or
> troubleshooting what I'm looking at. What is required, and does
> anybody locally have that sort of equipment?
See above. What you already have should be adequate unless you flub
the assembly.
> 2. What about the TIB kit? This looks like an easy kit to build and
> I don't expect it to require any after-building tuning.
I use one of these for 222, and it was very easy to assemble and works
quite nicely. Of course, I couldn't leave well enough alone, and I
re-designed mine. The TIB generates a negative voltage which is
brought back to the IF radio's ALC input to throttle back its power
output to a level safe for the transverter. The 222-28 puts out 25
watts when driven fully. My RFC 3-211 wants 2 watts of input for 110
watts of output. A bit of a mis-match. So I added an extra box with a
7-position rotary switch that gave me the ability to go from OFF to
5, 10, or 25 watts out; and also 1 watt out plus turn on the RFC amp
to get 50 watts, and also 2 watts out plus turn on the RFC amp to
get 110 watts. The 7th position is another OFF position. Way over-
kill, I could easily get along just fine with 2 watts, 25 watts, and
2 watts plus amp = 110 watts, and be done with it. But it was fun to
tinker with the design and get it to play. And no way to accidentally
transmit 25 watts into the amp that only wants 2 watts.
The original design includes nice things like splitting out the TxIF
and RxIF for you, and automatically switching the IF radio's HF
antenna port to another SO-239 (to which you hook your real HF antenna
feed), and when the TIB is powered down, the transverter gets out of
the way and go right to the HF antenna. Same principle would apply
to 2 meters if using the TIB with a 144 MHz IF rig for the 902 MHz
or higher transverters. I wired mine up so that the TIB was powered
from the +13.8v output of the IC-706, so that it would be impossible
to lose ALC voltage and allow the radio to transmit full power into
the transverter. If the radio is on, the TIB interface is powered,
though the OFF positions still allow you to disable the transverter
and go to the HF port (or 2 meter port in your case).
> 3. I can't recall seeing commercial SWR meters for the higher bands
> (902, 1.2G etc). Where do you get them from, or how do you build
> them?
I use a Diamond SX-1000. It has two sensors (two input and two output
jacks) and four band positions. 1.8-180 MHz, 430-450 MHz, 800-930 MHz,
and 1240-1300 MHz. Full-scale sensitivity is 5, 20, or 200 watts. Has
your typical FWD, REF, and SWR readings. RF Parts is the parent
company of Diamond, and they often have refurbished models for sale
with a full guarantee for a bit of a discount, which is what I did.
As Chris pointed out, the other common solution is a Bird 43 and a
bucketfull of slugs for the bands and power levels you want.
There was an article in QST awhile back describing a kit you could
build to monitor up to 4 channels and display power/SWR on an LCD
display. LDG electronics sold it for awhile, but no longer. And they
had plans for an HF sensor and a VHF sensor, but nothing for the
microwave bands. Bummer.
> 4. What frequency range do these transverters cover? That is,
> 1296 - 144 obviously covers more than just that one frequency,
> but their literature doesn't indicate what the range actually is.
If your IF radio tunes 144-148, then the 1296 transverter will tune
from 1296-1300 MHz. Everything is simply offset by 1152 MHz.
On the 900 MHz band, some people use 902 <-> 144 and some people use
903 <-> 144. Other than that, the same principle applies. All RF
frequencies are offset by 758 or 759 MHz respectively, giving you a
tuning range of 902-906 or 903-907 MHz.
With my 222 transverter, 222 becomes 28, so the IF radio has to cover
28-31 MHz in order to work 222-225 MHz. As it turns out, that's not a
problem, because the IF radio is an Icom IC-706 MkII, which will
transmit 28.0 - 30.0 (for some reason it doesn't stop at 29.7), but
will happily receive all the way to 200 MHz by itself. And how nice
of the ARRL to design the 222-225 MHz band plan so that the only
activity in the 224-225 range (where I can only receive) is repeater
OUTPUTS, meaning I don't want or need to transmit there anyway.
> 5. So, what do AOS and and TIB stand for?
I think I once knew what AOS meant, but the brain cells are failing me
now. A peek at the DEM web site also failed to refresh my failing
recollection. I'm not quite sure what Chris's answer means, either.
As Chris said, TIB = Transverter Interface Board.
Just in case you somehow missed these pages on the DEM site...
Transverter interfacing guide
http://www.downeastmicrowave.com/Inter.htm
AOS product description
http://www.downeastmicrowave.com/aos.htm
TIB product description
http://www.downeastmicrowave.com/tib.htm
and the Diamond power meters web page:
http://www.rfparts.com/diawatt.html
Hope that helps.
73 de W0JT