I’m searching for a SSB filter for my FT817 and needless to say…… the original Yaesu / Collins ones seem to be quite difficult to find. This one came up as a compatible alternative…… has anyone tried one out and able to relay any comments?
It’s nowhere near the performance of the Collins mechanical filter. Collins no longer make the filter elements which is why they are hard to find.
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73 Chris
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About 15 years ago a friend installed a Yaesu YF-122S filter in his FT817, and was disappointed to find that he not only could not hear any difference, he could not measure any difference too! We decided that either the YF-122S filter was poor, or there was some signal bleed-around the filter.
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Interesting… was it a new or used filter? Plus, how do you get to hear whether there is any difference? Listen via an SDR?
Repeated pressing of 7C (NAR) in the 817 menu lets you alternate between filters. A tighter filter should give a more restricted audio range and better adjacent channel rejection. He never said if it was new but in those days it was available from stock.
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I have had good experience with Inrad filters (I’ve got their 500Hz CW filters in my 817 and my 920). Their FT-817 page has two SSB filters and they appear to have both the 2kHz and the 2.5kHz ones in stock. Although their page does say they are using up their stock and that Collins don’t make them any more.
See International Radio ::...
But as Brian says, I doubt you will hear much difference. What width is the standard filter built into the rig?
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The handbook says 2.2 kHz at -6 dB, 4.5 at -60, which is fairly good. I think that for me any narrower would degrade readability.
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The performance of secondary filters in the FT-817 is limited by the PCB design in the radio itself. Even a good crystal filter yields quite modest performance with poor stop band attenuation. The additional SSB filter in particular is almost useless due to other constraints within the radio. An additional ceramic filter for SSB is money down the drain really.
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If there seems to be no differences when pressing NAR, check that you have set the appropriate menu item for an optional filter. You need to specify the YF122S. Otherwise the logic in the radio will not switch over to the alternative filter on SSB.
I have tried one of the Collins filters and it was markedly different from the stock Murata filter. I needed to change the carrier frequency to get it to sound good, but it was then very good, as you’d expect, and much better than the stock ssb filter.
Once the menu item is set correctly for an SSB filter, the NAR option described above will switch over to the alternative filter.
Andrew VK1DA/VK2DA
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All the details for installing a new filter are given on page 74 of the manual, my friend followed them.
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Hi Brian,
Yes, it’s a bit hard to advise someone retrospectively, especially 15 years in the past, but I posted the advice in case someone else finds a similar problem and is puzzled by finding no difference when switching to the NAR option.
73 Andrew VK1DA/VK2DA
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Regarding the optional filter offered, as some of these filter options have a wider bandwidth than the standard (Murata) ceramic filter, it will clearly not offer any better selectivity. It may well offer a wider bandwidth for reception and transmission, which changes the apparent quality of the signals received. But with most other signals being transmitted at about 2.4 khz bandwidth, the extra bandwidth simply increases the noise without making any improvement in the quality of a 2.4 khz signal being heard. I can’t see any benefit in a wider filter, so my advice would be to decline the offer.
73 Andrew VK1DA/VK2DA
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That was what I concluded when I fitted mine.
73,
Rod
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I think that with particularly an SSB filter it is the skirt bandwidth that makes the difference, you can only go so far with narrowing the -6 dB width before reducing readability. If you look at the specifications, the YF-122S filter is actually wider than the provided filter. I would guess that the only advantage gained from installing a YF-122S filter is very slightly better audio fidelity, which is why I didn’t bother with it. OTOH, if I had been into CW I would have immediately installed a narrow filter when I bought my FT817.
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I bought both the.narrow SSB and a CW Collins filters when I heard they were going out of production. I then found I could only have one alternative filter, so chose the CW filter. It was good but I had to make sure the menu was set to recognise it and then select it prior to use. See comments by VK1DA.
The SSB filter is surplus and the 817 is not much used either. There are better rigs. I was intending to use it with transvertors and may still do so.
73
Ron
VK3AFW
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Somewhere I’ve seen a 3rd party board that allows you to fit both of the filter modules after removing them from their standard PCBs. You select which one the narrow button uses by setting either SSB or CW in the menu.
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Agreed Brian. I have a 1.8kHz filter in my TS-430S and its usefulness is restricted by the characteristics of the operator’s voice. It suits some people very well, others just become less intelligible. I certainly would not have purchased a narrow SSB filter had it not come with the rig. Now a CW filter, that’s a different matter entirely, but of course you will have to take my word on that. 
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Hi Colin,
Yes there was a group advertising with the W4RT callsign, they offered various filters and upgrades for the 817 among other radios including the IC703. Their dual filter board substituted the mech filter from the YF122s for the stock ceramic filter, removing the old filter. In CW mode, the NAR option switched in the CW filter chosen, either the 500 or 300 hz mech filter. When Collins stopped making those filters, W4RT no longer offered the dual filter boards and all of the collins mech filters. I have the dual filter board in my IC703 and it is a very good mod to that already good radio.
I think it was W4RT whose website contained an article extolling the virtues of the low passband ripple in the mechanical filters (<3db) compared with the much greater ripple in a crystal or ceramic filter. The perceived improvement in the signal quality was said to be substantial. I guess that is one reason why the Collins S line always sounded so good.
When I had the Collins SSB filter in my 817, I found there was a marked difference in the perceived sound of the receiver between USB and LSB. I experimented with the carrier settings in the extended menu, until the USB and LSB sounded similar in tone and both tuned through a carrier in the expected way. A critical ear is essential for such activities.
A lot simpler than grinding crystals.
73 Andrew VK1DA/VK2DA
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Perhaps not! The DSP on my FT857 kicks in with a 240 Hz audio bandwidth in CW, and I have a 500 Hz filter in my TS-520S for CW, so I have a good idea of how desirable they are even though I choose not to operate CW.
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