The FT920 Resource Page
Last update: Monday, 10-Mar-2014 15:33:41 GMT

December 22, 1997

INRAD let me know that the SSB filters will be about 10 weeks out. If you want to know more information about other filters available from INRAD, go to their web page.

December 21, 1997

There is a minor problem with the new SSB filter. I thought it was working well, when in fact it wasn't working at all. George at INRAD (International Radio) was kind enough to call me saturday morning, and we discussed the problem at great length. Then I got a call from Don Baughman, K7MX, who also has one, and he explained in greater detail what the problem was. Don is the one who actually found it. Because of a different grounding for the Yaesu filter, the INRAD filter will not work properly if installed in place of the stock filter. The INRAD filter must be wired in place to work.

I believe that all is working now, and George is going to be making a change to the filter which will cause some delays in shipping (I believe). My hat goes off to George and Georgia for their great customer service. They are really trying offer a drop in solution for a lot of radios.

I will be taking about 10 days off over the holidays, and I really hope to spend a bit of time on the air. If you hear me (mostly on 20m and 15m and during the RTTY roundup), please give me a shout, and give me a signal report. I'd really like to know how this combination of filters works.

December 17, 1997

Just got done with my first QSO since installing the new SSB filter. The INRAD filter has a very nice sound. I can only describe it as warm. The selectivity is great and it makes the receive audio sound great. The report given was also positive. Too bad I cannot have both filters for an A/B comparison.

All in all, right now I am a very happy guy. Now we'll just have to wait for a good phone contest to come along to see how it does. Perhaps it is time to look at getting the AM filter, and try out a new mode.

December 16, 1997

The INRAD 2.1kHz SSB filter has arrived. I found that the installation process is relatively simple, but not for the faint of heart. It requires that you remove the main circuit board, and unsolder the existing filter. If you are not comfortable working with these components, PLEASE do not risk damaging your radio; get the assistance of someone who is experienced with this type of work.

In order to remove the main circuit board, you need to remove the bottom cover just as when installing the CW or AM filters. The next step is to remove the DSP unit. Looking at the board from the back of the radio (upside down), its the large shielded unit at the right towards the front of the radio. Remove the three screws holding it in place, and gently lift it straight up. You can then remove the wires plugged into the side of the DSP, and it will lay nicely over the side of the radio.

Next, remove the twelve screws holding the main circuit board in place, and gently slide the board to the front of the radio. As you slide it, lift the front edge so that you are able to get the connectors at the back of the board to slide out of the radio chassis. At this point you can then flip the board over, toward the front of the radio (you don't need to disconnect the ribbon cables.) With some solder wick, you can remove the solder from the original filter, and then it will be possible to pop that filter out. Be careful, when removing the solder, to ensure that you do not overheat the filter (which will loosen the posts on the filter), or that you do not overheat the traces or nearby components.

The INRAD filter is a very nice piece of work. It looks great, and fits perfectly. Solder the four posts in place, and reassemble the radio.

Replace the twelve screws holding the main board in place, and then reconnect the DSP unit. Be sure to line up the edge connector correctly. Then replace the three screws that hold the DSP. Finally, replace the bottom cover, and test your installation.

I'll have more observations about the performance of the filter, after I get a chance to actually put it on the air. I'll be looking for reports about the signal, and sound quality, as well as how the filter compares to the stock filter.

December 15, 1997

Just to clarify things... I have not yet received my SSB filter from INRAD. It should arrive in the next day or two (of course considering the usual delays due to the season). As soon as the filter arrives, and I have a chance to install it, comments will be placed here.

December 11, 1997

There is information about modifying the FT920 for open transmit circulating around the internet. I have only a few comments about these mods.

First, use them at your own risk. It has been mentioned that one owner screwed up his radio, and had to have it repaired by Yaesu. Then there is the reminder that transmitting outside the band edges is not allowed except in certain circumstances (like MARS or CAP licensing).

If you need to have your radio modified for transmitting outside the Amateur bands, I suggest having it done by an authorized Yaesu source. It shouldn't cost you anything.

FLASH: I just received notification that INRAD will have lots of new filters for the FT920 "imminently". In addition to the 400hz CW filter (#701-A), the following filters will be available shortly.

Part no.ModeBandwidthPriceinstallation
#708-ACW250Hz$110on a custom PC board
#710-AAM6.0kHz$110on a custom PC board
#709SSB2.1kHz$110solder in (replaces original filter)
#711SSB1.8kHz$110solder in (replaces original filter)

The #709 filter tested out:

        2.1kHz @ -6dB
        3.1kHz @ -60dB
        Shape Factor = 1.47
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