[NLRS] 10 Ghz..... beginner looking for help...

Sat Aug 8 00:14:52 EDT 2015

On 8/7/2015 5:02 PM, Gregg Lind wrote:
>
>
> I purchased the 10 Ghz Demi transverter at the CSVHF conf in Denver now I
> am learning what it takes to get on 10 Ghz... The transverter traveled back
> to  DEMI since Steve offered at the conference to check it out and make
> sure it working... so I am trying to get prepared so I can use it this
> summer if at all possible... for a contest..
>
> These are the items I am trying to purchase and find in the quest to get on
> 10Ghz
>
> 10 Ghz feed horn and waveguide to SMA... to use on a TVRO dish

The TVRO feed isn't bad. I started with a new Direct TV dish and feed. I 
took the circuit board out of the LNB, then I pulled the dielectric 
circular polarization septum out and drilled out the die casting to 3/4" 
diameter. I made a plate to short where the circuit board had been, and 
drilled and tapped for a SMA connector based on the dimensions for using 
3/4" water pipe for 10 GHz waveguide from ARRL publications. It measured 
32 DBi gain at a MUD and has been working decently. I think K0AWU has a 
web page about the NLRS conversion started by N0EDV that involves a 
tuning screw. I haven't checked for match carefully, but I think mine is 
working decently.

There are plans for an easy to build rectangular horn in Paul Wade's 
original QEX article about using the RCA dish for 10 GHz. Its on his 
W1GHZ web pages or antenna book I believe. Those that regularly beat me 
in the 10G+ contest use that feed. I need to add a preamp and more 
transmitter gain but will only get the preamp working by next weekend.
>
> I currently have 2 dishes (oblong multi-lnb versions) -  not round dishes
> but I have a number of leads on a "Direct Dish"  I hope to get one in the
> next few days.

The near round dish is probably a better parabolic than the oblong ones. 
I don't know their shape, but I figure on measuring some day as I have 
acquired some just to learn what the shape is. I suspect its parabolic 
in the short cross section and cylindrical in the long one so the offset 
feeds don't make such a mess as a pure parabolic will with offset feeds.
>
> I need a tripod to support the system- any suggestion for what to buy and
> look for? What to purchase? Where to look... I looked at camera tripods not
> sure this enough support... so I been looking for heavy duty.

Heavy duty camera tripods, the kind with leg braces hold up pretty well. 
I'm using a Quick-set Sampson. I made my own tilt head from a couple 
unistrut angle brackets. For a dish pivot (my dish holds the transverter 
and the IF) I got a category 2 to category 3 tractor three point lift 
sleeve welded to a plate that I bolted to the bottom of the dish frame 
with an angle block so the pivot is nearly vertical when the elevation 
is at the horizon. I use a shortened three point implement lift pin for 
the pivot. I also made a stubby quad pod to use from inside the truck 
shell or on the truck roof with a similar elevation tilt using two 
unistrut angle brackets. I have a picture of the tilt scheme on line at 
www.geraldj.networkiowa.com/PIX/TripodTiltHead.JPG and the dish mount at 
www.geraldj.networkiowa.com/PIX/DishMount.jpg case on these links is 
critical. I used a fine thread bolt for the clamp with a couple 
Belleville spring washers. I used a bit of channel to hold the bolt head 
from turning so it takes only one wrench to adjust the tilt tension.

I've seen sturdy camera tripods modified with longer braces so the legs 
spread further. On a lighter tripod I've used a bungee cord to hang my 
battery from the tripod for better stability. I have turned tripods over 
more than once. Last spring in the garage it broke the IF radio 
encoders. While roving its landed in grass so far every time.
>
> 2M IF rig for the transverter. I have a Icom 7000 that I can use but it
> looks like most people will dedicate a radio to the setup... This is my
> main radio for all my rover transverters... so I am not sure I want to
> "unhook this for 10 Ghz".

FT817 is very nice, I like the FT857D because the DSP has helped me make 
contacts. There is a Kenwood single band multimode that has been used, I 
sold one to Fred Spinner last time CSVHF was in Cedar Rapids. I have 
looked at the FT290RII as an IF and have one that I don't like very 
well. Neither of these has room for a CW filter and I've found on long 
paths that the CW filter helped make the contact. And I've not found an 
audio filter gave the same enhancement of signal to noise ratio of the 
500 Hz IF filter. I've seen FLEX 1500 and Elekraft K3 used as IFs in 
Minnesota. If I had gone to Denver, this 290RII would have been on the 
swap meet table. It has the power amp attachment and a bias problem so 
the power amp only amplifies drive peaks. It would be nicer as an IF 
with the low power connector on the back replacing the PA. I haven't dug 
in to see if it can be fixed. The SSB looks good on the scope on low 
power but rotten on high power.

I have the 2m output of my transverter 857D turned down 
(www.geraldj.networkiowa.com/papers/CSVHF2010/xvtr857align.pdf) to two 
watts to keep from overdriving the DEMI transverter which can be set to 
take any trsmitter power from milliwatts to 10 watts. I don't like 
driving it with 10 watts though it can be adjusted to not be overdriven 
(article at www.geraldj.networkiowa.com/papers/AnticlippinB.pdf) The 
trouble with dumping 10 watts into the transverter internal dummy load 
is that heats the transverter which makes the crystal change frequency 
while transmitting. I have slowed that by cutting the IF power and then 
I made sure I have a 40 degree C positive temperature coefficient 
thermistor against the crystal and the crystal is surrounded by bits of 
dow blue board to slow its temperature changes from external influences. 
Some day when I'm in the transverter far enough to change the drive 
options I may lower it even more.

Turning down the output by lowering the transmitter gain works better 
than depending on ALC power control which tends to spike at the 
beginning of each transmission causing splatter at the least or fried 
transverter parts sometimes.
>
> I will be traveling to MSP in the next few weeks to see my nieces new
> baby... so if you had something I maybe able to accommodate a eyeball
> Qso...

  A Saturday morning breakfast would be a good time to meet up there.
>
> Gregg Lind
> KC0SKM
> gregg at thelinds.net
> 319-431-7235
> ______________________________________________________________
>
73, Jerry, K0CQ