Bert Modderman Engineer

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I have 4 different filters available for now and i hope to have a wider choice of filters in the future.
you can also ask for custom designs. i already made several for instance for 2500mhz and 2200mhz


NEW 2320 2400MHz filter! 100 euro

The filter shown far below on this page for 2320 to 2400mhz was to narrow and many customers where not happy with its bandpass.
So i decided to create a new one myself with 2 notch filters.
this filter has 0.75db loss max from 2330 to 2490 and 1db at 2320 and 2400. 2300 to 2320 also usable.
im actualy measuring lower loss i think. analyzer says 0.36db for 2360.
need to make a few more filters to find optimum but max loss will be 0.75db garantueed.
wifi supression above 2400mhz can be done in 2 ways. agressive or mild.
see graphs. the agressive wifi suppression setting starts falling down from 2390 and 2425 is almost 50db suppressed.
the mild setting makes the filter run to 2400mhz with 2425mhz 15db suppressed and 2450 approx 40db.



graph with the hard setting for wifi suppression. i doubt anyone needs this kind of suppression but show what the filter is capable off.

below has an integrated 2db scale graph that shows ripple of about 0.25db from 2330 to 2390.
markers are 2320 and 2400 and center 2360. (the 2 outside are 2425 and 2450)


Because the lower filter for 13cm with notches was realy hard to reproduce with good specs i decided
to redesign new 13cm filters.
the first attempt is this low loss, very broadband, duplex filter.
50db down at 1245, 60db down or more from 1260 and above.
downside, only 10db down at 2500 and 14db down at 2200, but 45db down at 2000

housing is only 9cm x 4cm and losses are around 0.3db to 0.5db from 2330mhz to 2390mhz
this filter is 80 euro and is only ideal for duplexing with 23cm and blocking 1800mhz signals.
if wifi is your problem then this is not your filter.
but is excellent for the dx-er and contester because of its very low loss and good attenuation of 23cm.


 

2320 MHz DC9XG SSB interdigital filter 80 euro

 


2320-2400 MHz interdigital filter with 2 adjustable notches 100 euro.

Specifically designed for atv use. Also blocks wifi interference.

It looks expensive but its alot of work on the lathe and milling machine to make it work good.
All rods need to be turned exactly to length and all the holes need to be tapped straight.

Thanx to PE1KYC who improved and adjusted the design of DC9XG for atv use

Here the filter is tuned for 2345-2390 bandpass and its blocking wifi and everything from 2410 and above:

The bandpass has 0.5db loss. The 40db value could be more because that was the end of my watt meter.
This is the best the filter can do, i could not get the bandpass wider or the bandstop closer (without hurting the bandpass).
Without network analyzer it is very hard to allign the filter like this.

The filter can also be tuned to 2320 and having a strong bandstop at 2360 or 2387mhz.

 

Duplexing via a repeater is now possible.
I used 2 beams side by side with a distance of 50cm away from eachother to duplex
with a repeater that was received B5, but only just. It had a few spikes in the screen.

This picture was received back from the repeater on 2352 while i was transmitting at 1280mhz with 300watt+