Accessories

Filters

FT1000MP Filters (The Basics by WD8ARZ)

I bought the 1000MP without any filters installed. I am thinking about buying some soon, however as I do not have plans in the immediate future to buy all of them, I would very much appreciate ideas from you guys on which 2 (or 3) to buy first. Please note that the 2Khz SSB filter will be one of them, which CW filter should I then go for? LA6LHA, Harald
 

Hello Harald, and you have asked a very good and popular question concerning filters for the FT-1000MP. What I see in your request are two different questions. One is what manufacture and type of filter should you get as regard to quality, and the other is what bandwidth should you get. As for quality, that does have a range and just because a manufacture of
filters had great quality at one time doesn't mean that they do today. I have heard of filters being bought from the major manufactures, and some third party suppliers, that at times are great filters, but also that at times some poor quality ones are released. Poor quality ones are not just a low number of poles, or poor quality components, but the matching of those
components to each other and properly centered with the right bandwidth at the center frequency.... and I am not getting into losses and impedance matching. Make the manufacture that you buy the filters from provide you with the technical specifications for the filters you want, and to make sure that they supply the curves for those filters. Those that can not supply that information are in the wrong line of work. Did I mention warranty and a return policy?

The question about what bandwidth to go with is purely a personal choice. That choice is directed mostly by the modes you operate, and what those modes need for bandwidth to perform properly. Most digital modes would start to get choked off if you use less than 500hz filters. Of course some rtty modes would do just fine with 250hz. CW can be 200hz and less. If you are not a hard core purist in some mode, the bandwidths as indicated on the FT-1000MP filter panel would be great choices for the wide range of modes in use today. Some final observations: Don't forget the filter option for the sub receiver. Remember that each filter you add needs to be turned on in the menu for that filter selection before they will work (page 100 in the owners manual). Filters bandwidths don't have to match the labeling in the filter menu's,
the front panel selection labels, or the manual. If you change the main receiver Collins Mechanical Filter, you can use it in the subreceiver.
 

Remember that there are two IF's to put filters in for the best result for each bandwidth. If only doing one, go with the one closest to the front end, in this case the 8.2Mhz 2nd IF. Most importantly be aware that filters from most manufactures come in two styles. One is the filter housing all by itself and generally is a solder in type. The other comes on a printed circuit module that plugs into the radio. Your owners manual covers that detail, but the text and pictures confuse some. The correct identification for the two types are: YF filters are on the plug-in printed circuit boards, and the XF filters are not. Most of the filters in the FT-1000MP are the YF type, and probably what you need to order. A couple of filter in the radio are the XF type, so just make sure as to type needed before ordering. You will find as a result of adding the additional filters, that not only do you gain the bandwidth improvements for the modes you use them with, but also that the If shift, width and shift controls are more effective as a result. Filters are the best way to go for improving any radio. DSP as it is used today will not bring the effectiveness that filters in the early IF stages bring. By filtering out signals and noise not needed for the operation at hand, the system AGC lets you copy weak signals that would not be heard in the presence of a strong signal. With out the right filters for the mode in use, the AGC will reduce the radio sensitivity for strong signals in the passband causing weak ones to be much tougher to imposable to pull out. DSP filter is in later stages and will only treat the audio and maybe the last if stage, so it has to work with all the crude that comes at it, and so does your ears.

Last tidbit. Don't forget to use the Bandwidth Diversity Reception that you can do with the dual receiver and filter options. Just make sure to use stereo speakers or headphones and that the menu options for audio out is not set to mono. You will be amazed at what your ear and brain can do to pull out signals this way. I also use Mode Diversity to improve copy of AM signals. USB on the sub receiver, and LSB on the main. Best results are when using stereo Headphones, sometimes you can actually hear three aspects of the audio this way. One in the left ear, one in the right, and the other in center. Great way for pulling audio out of noise and fading conditions. Other modes work this way too, and the extra filters go along way to make the right choice for most situations. Let us know what choices you make and who you order them from, and most importantly, the results you have with them. Looking forward to your future feedback. Bill WD8ARZ
wd8arz@ix.netcom.com