Monday, 10-Mar-2014 15:33:41 GMT
April 22, 1998
First impressions of the new filter assembly: It looks great, and works just as well. I was tuning around 20m last night, and the filter selectivity is fantastic. Keep in mind that I can only go by my ears, but it is nice to be able to tune about 3kHz either side of an S9+20 signal, and not hear any splatter, bleed thru or any part of that signal. The adapter has really improved the selectivity of the filter when compared to my lousy (wired in) installation. And the filter was better than the OEM even then.
I did check into the local 6m net last night, and let them know about the new filter assembly. I didn't transmit much, but I did listen for a couple of hours, and I am very happy with the way the radio sounds. I might just put the OEM filter back in to remind myself how much of a difference the Inrad filter makes.
April 21, 1998
Happy day... my radio has returned home from its journey to Oregon. The UPS driver was kind enough to NOT leave it at the front gate (as they have been known to do in the past). I did, however, have to track him down in my housing tract to retrieve the box.
Now that the radio has been unpacked, the first thing to do was look at the filter installation and the adapter board. The adapter board is a beautiful piece of work. I have to say that I am impressed. The whole assembly looks far better than I expected, and my hat's off to George.
Tonight, I hope to get on the air... it has been nearly two weeks, and I am getting a little itchy. Perhaps a little RTTY and then a little phone? I'll look for a crowded section of the bands to give a little (perception) test of the filter. More comments after I get back on the air.
April 14, 1998
I just received a fax from International Radio showing the 709, 711, and OEM filters.
George's notes: The outer curve shows the typical OEM filter. The middle curve is for the IR #709 and the inner curve is for the IR #711 filter. The flyback responses are from the OEM unit as the IR filters show no flyback in the 80dB dynamic range which is graphed. Measured bandwidths are as follows:
|Filter||-6 dB||-60 dB||Shape factor
|OEM||2450 Hz||4300 Hz||1.8
|#709||2125 Hz||3225 Hz||1.5
|#711||1875 Hz||2825 Hz||1.5
April 13, 1998
International Radio emailed me over the weekend, and said that they will be announcing that the SSB filters for the FT920 are ready to go. They have had my radio for a few days, and had the opportunity to test a few things. George also sent me a graph showing the difference between the 709A (2.1kHz filter) and the OEM 2.4kHz filter. I hope to get more graphs showing the 1.8kHz filter as well.
My installation of the 709A filter was not the greatest (I simply wired it in place). George mentioned that with the adapter in place, and with the grounding that it provides, there is an addition 10db of selectivity beyond what I was getting.
Addendum: I just got off the phone with International Radio, and the SSB filters are going to ship. We are happy with the results, and hope to have photos, installation instructions, and graphs for these filters very soon.
April 11, 1998
Just received word from George at International Radio, that the filter adapter works great. He reports that there is now better selectivity and the possibility for other great things from Inrad. More information to follow as it becomes available!
April 10, 1998
I have shipped my FT920 off to International Radio in Oregon. The parts for the SSB filters are in, and George is working with my radio to ensure that everything works well before any filter kits are shipped. Hopefully, all will go as planned, and I'll have more information soon, as well as comparisions between the stock filter, and the 2.1kHz, and 1.8kHz filters from Inrad.
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, Mark A. Downing
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