Rectangular Waveguide Feed with Septum Polarizer

Septum feed only = $350.00 Scalar Brackets = $75.00 Mounting System = $175

Specifications:

TX port Return Loss = > 30dB (1.08:1 VSWR)

RX port Return Loss = > 21dB (1.2:1 VSWR)

Isolation TX from RX = > 30dB

Weight = 9 pounds

Very sturdy construction, designed for rear mounting with four 1/4-20 tapped holes for mounting

the feed or for mounting LNA, etc. Also can be mounted with my feed mounting system.

Septum polarizer provides excellent circularity with no tedious tuning adjustments required

Connectors: Typically N-type on TX port, and SMA on RX port. RX can be N-type if desired

Pricing: You might ask how I priced the feed. First for starters, the materials for the feed alone cost

over $175. The construction requires precisely drilling 52 holes. 34 of these holes are

tapped. Drilling and tapping edgewise into 1/4" 6061 aluminum is tricky. Precisely cutting the

stair-stepped septum is excruciating and getting a perfect fit inside the tube can be

challenging. Same goes for the rear plate. So obviously the majority of the expense is labor,

but it is much much less per hour than a typical consulting or fabrication rate. I’m not doing

this to make money, but much more so to encourage 1296 MHz EME operation. The scalar brackets

and mounting system are even more labor intensive, so are actually quite a bargain.

Scalar (choke) ring info:

I have normally recommended the cake pan scalar. The Fat Daddio PRD-183 18" x 3" pan is the

closest dimension to the optimum size based on many studies. The pan has normally been available

on Amazon.com for around $35 but recently has not been in stock. If you want one of these pans,

I may have info on other sources, so send me a note.

On my system the pan has improved my sun noise reading by about 1.1 dB, so I consider it

worthwhile. I have heard others claiming greater improvement. Many folks are concerned about

feed blockage especially on smaller dishes. The blockage on a 3 meter dish is not significant

compared to the benefit of having a scalar.

More Information:

Pictures of feed with scalar (not included): http://kl6m.com/23cm/cakepan/cakepan.html

Construction Techniques Paper from EME2010: http://kl6m.com/23cm/23CM-SEPTUM-FEED.pdf

Additional info on the use of the septum feed: http://ptt-ak.com/SeptumFeed/feednotes.pdf

KL6M Septum Feed Mount

IMG_1091.JPG
2,717.31 KB

This mounting system has set screws which allow easy adjustment of focal point using sun noise.

This allows you to adjust for OPTIMUM performance.

I have enough material for four of these. Not sure I will make any more after this.

septum-mount3Mdish.pdf (I have drawings of other sizes on request)

1296 MHz (23cm) is a fantastic band for EME. This is where the majority of EME takes place lately.

This is a screen shot (CW) at my station from a recent DUBUS EME contest: http://kl6m.com/sdr/dubus2017a.jpg

For more information contact Mike, KL6M at arrl.net or mike at KL6M.com