Inexpensive inline filter


#1

Dont have the Tools to build so I need to go the purchase route but the funds are limited.

Ive been digging through the net like crazy trying to find a inline bandpass that would work to cut down some of the
noise I have around here. I have 2 massive cell towers less than a mile from me. (plus my own Ham Radio station).


#2

Not sure how limited the funds are… This seems to be a nice product for the purpose.
But building one is fun too (see my blog for details). Or maybe find a neighbour ham who likes plumbing…
/paul pa3dsb


#3

Get this one from Mini-Circuits. It is an SMA inline for only $40. It isn’t dead on, but it is close enough to 1090Mhz (it is 1065 Mhz). Have one connected to my SBS-3.
minicircuits.com/MCLStore/Mo … 0529614623


#4

This looks interesting rtl-sdr.com/update-homemade- … -same-pcb/

would like more details … it certainly looks low cost.


#5

Acutually that one looked interesting and I can solder (would only do the filter part) but making the Printed Circuit is the issue.


#6

[quote=“paulmerkx”]
Not sure how limited the funds are… This seems to be a nice product for the purpose.

that = 112 + US Dollars, way out of the wifes budget :slight_smile:[/quote]


#7

All you need these days is a laser jet printer, some PCB supplies and a bit of practice. I stopped making them because it just got to be annoying for me, but it’s not unrealistic to do. If you got a big enough group together you could order the PCBs already printed just needing soldering for fairly cheap as well.


#8

[quote=“w7psk”]

How does $81 sound? Filter with an amp…


#9

The article mentions a PCB fab plant that works from the drawing files for something like $10 inc postage for one to three peices (depends on required board size - which I haven’t had time to establish)


#10

I’ve had prototype PCBs made at https://oshpark.com . It didn’t cost too much and the quality was great.


#11

oshpark.com works from the Eagle .brd file and charges $5/in^2 for three boards. This board is 4.14 x 1.8 inches, so it works out to $37.25 for three of them. They come with a pretty purple soldermask and gold-plate finish.

If the layout could be shrunk to fit in a 5 x 10 cm rectangle (which, on first glance, looks pretty do-able), you could get 20 boards done by seeedstudio.com for $41.90, still with the ENIG finish (but with green soldermask rather than purple). If HASL is OK, that knocks $20 off the price. This price is for 10 ea., 10 x 10 boards that would need to be cut in two to yield 20 boards. Their price for 10 ea., 5 x 10 cm boards is only a few dollars less than their price for 10 ea., 10 x 10 cm boards.


#12

I’d like to get in on a group buy, if this is where the discussion is leading.


#13

I wasn’t really suggesting a group buy, but I guess that’s kind of an obvious way for it to go. There are at least three different Chinese companies (itead, seeed, and elecrow) offering PCB fab services in lots of 10 boards, often cheaper than you’d pay for a single board stateside. And for whatever reason, 5 x 10 cm is almost the same price as 10 x 10 cm with all of them. If we didn’t need a gold finish, the price per board could be just over $1.

Just to be clear, I’m not volunteering to coordinate a group buy. The board size would need to be reduced by at least 6 mm on the long dimension (the price increases significantly if it’s over 10 cm), and while I might feel comfortable tinkering with a simple, low-frequency design, I honestly have no idea what if any effect that would have on this design. I’m quite sure it can be done; I just don’t have the knowledge/skill to be comfortable doing it. I also don’t have access to any tools to cut the boards apart at the moment.

The rest of the parts look like they would be very inexpensive–the SMA connectors would be the most expensive by far, at $3.25 ea.; the remainder of the parts would total less than $1.


#14

I’d be interested in a couple on a group order. Perhaps a separate discussion would be in order.


#15

I’d be interested too. I wonder if one of the cheap ebay suppliers in HK would be interested in supplying these (copyright permissions etc allowing) since they have access to cheap fab plants and China post. or maybe one of the Antenna suppliers from Slovakia / Bulgaria.