Inrad Roofing Filter

The amplifier provides enough gain to overcome the filter insertion loss.

Inrad roofing filter.

Inrad roofing filters for the ft dx5000 bench results and observations based on an idea from daniel sandu yo3gjc inrad has taken their stock series of 9mhz filters and fitted them to a daughter card allowing drop in use in the yaesu ft dx5000 series rigs. A two screw terminal board connects to 12v and ground. Installation is simple and requires soldering the 12v and ground wires. The improvement in first if selectivity is dramatic.

One coax is moved and a coax jumper is added. The amplifier provides enough gain to override the filter insertion loss plus a db or two. The wider curve is the oem response and the narrow curve is with the inrad roofing filter mod added. A four position dip switch is used to set up the roofing filter function.

The plot below shows the sweep frequency response of the rf board in an ic 775 radio. This mod works in all versions of the yaesu ft 1000mp line of radios. Inrad roofing filters can substantially reduce the third order intermod from multiple strong signals in the 2 20khz range on either side of the tuned frequency. The n1 n2 switching cable gets extended and plugged into the inrad board.

The icom ic 756proiii roofing filter mod consists of a 6 pole 4 to 5 khz wide filter followed by a high dynamic range feedback amplifier. Twice another frequency referred to as the third order k f 1 f 2 2 response. Two coax cables insert the roofing filter between the rf board and the 9 mhz if board. The 3oimd response of your receiver can generate an interfering signal s right on top of the one you are listening to from two or more signals outside your lis.

Yaesu ft 1000 ft 1000d roofing filter. A supplied jumper cable connects back to the if board. This roofing filter can help reduce the third order intermodulation from multiple strong signals in the 2 to 20 khz region either side of the tuned frequency. This section allows you to select specific add on features for your particular rig manufacturer.

Here we take a look at how these inrad filters measure up to their yaesu alternatives. Installing the inrad roofing filter the mp roofing filter mod consists of a 6 pole 4 khz wide filter followed by a high dynamic range feedback amplifier. Please see our document titled a few words about roofing filters for more details. The plot below shows the sweep frequency response of the front end and first if filter in an ic 756proiii radio.

Select the radio of your choice below to find the filters and or roofing modifications you seek. Filter insertion loss plus a few db.