Do I Really Need a 300Hz Roofing Filter?

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  • เผยแพร่เมื่อ 14 ม.ค. 2025

ความคิดเห็น • 45

  • @N1IA-4
    @N1IA-4 2 ปีที่แล้ว +1

    Great explanation of the filters and APF! Thank you for doing this.

    • @n4hnhradio
      @n4hnhradio  2 ปีที่แล้ว

      I’m glad you liked it.
      73, de N4HNH

  • @AmazingSteelers1933
    @AmazingSteelers1933 3 ปีที่แล้ว +1

    Thanks. This is very helpful. I was debating this very thing over the weekend. Same with the additional SSB filter on the FTDX101MP.

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว

      I’m so glad you found the video helpful! Welcome to the channel!
      73, de N4HNH

  • @Lync512
    @Lync512 2 ปีที่แล้ว +2

    Thanks for this video!
    I have a Yaesu ftdx10.
    I’m actually looking to get into CW and was debating if I needed the extra filter or not. Interference hasn’t really been an issue. I scan around the cw portion of the band and even with several strong signals I have no issue Making them out. As well this has rather good DSP since it is a SDR.
    I think the money will be better used for a nice key.
    73,
    De KE8GAH

    • @n4hnhradio
      @n4hnhradio  2 ปีที่แล้ว

      The 300 Hertz roofing filter helps the DSP do a better job of filtering but this is mainly needed during contest or emergency conditions, when the bands are extremely crowded.
      As far as keys go, don’t think that you have to buy the $350 keys. I use a $165 Kent TP1-B, and I will put it against a Begali or anything else in the $350+ realm.
      73, de N4HNH

  • @johnc3403
    @johnc3403 ปีที่แล้ว +3

    Looking for videos to decide whether to invest in the XF-127CN 300HZ filter for the FT-DX3000, I came across your video. Really the only video that addresses the decision whether the DX range of Yaesu rigs benefits from the 300Hz filter or not. I have to say, your advice about the APF is excellent. A narrow DSP and a narrow APF is a great combination, even with the 3000's stock 600Hz tightest roofing filter. ..but ...BUT, if you are a CW op that likes to work in the 300HZ range, believe me when I say, the CW decode with the optional XF-127CN 300Hz filter on the DX3000 is FAR nicer, more rounded, smoother and easier on the ear than with the stock 600Hz roofing filter with the 300Hz DSP set. To my ears, there is no comparison. The 300Hz roofing filter produces buttery smooth CW reception compared to the 300Hz DSP (with the stock 600Hz filter switched in). If you are a CW guy and work 300Hz bandwidth on the DX3000 or DX1200, pull the trigger on the XF-127CN. These great rigs deserve this great little filter. John EI5JS

    • @n4hnhradio
      @n4hnhradio  ปีที่แล้ว +1

      The DSP alone cannot make up for the heavy lifting provided by a roofing filter. But a tight roofing filter ahead of stellar DSP is a winning combination. You might like this video: th-cam.com/video/dBw5L2gXAf0/w-d-xo.html
      There is another video publishing on Friday, February 24, about chasing ghost stations. That video will focus on gain structure and filtering with some comparison between a stock 500Hz filter and the optional 300Hz filter.

    • @tomhelo4523
      @tomhelo4523 6 วันที่ผ่านมา

      Hi John,
      I followed your hint and bought a XF-127CN for my FTDX 3k. Question: In had a signifikant drop of the signal with the 300Hz Filter. I had to use the Amp 2 to compensate the drop. It ist much much more than the Switch from 1.5k to 600Hz. Defect? Vy 73

    • @n4hnhradio
      @n4hnhradio  6 วันที่ผ่านมา

      There is always insertion loss through a filter. It could be 6dB or so (=1 S-unit on an accurate S-meter). The receivers are so sensitive these days that we normally don’t need a preamp for most bands. I use IPO and sometimes up to 18dB of attenuation. So 6dB of insertion loss in order to improve selectivity is totally worth it. I cover this in other videos, including my “ghost station” videos.
      That said, don’t just equate S-meter readings with sensitivity. Even with an SDR that relies solely on DSP, if you narrow the digital filter enough, it will cause the S-meter to read lower. That is perfectly normal. Remember that the S-meter is supposed as represent the signal strength at the antenna input, but it is measured from the AGC - in the last stage of the receiver. The more narrow your filter width, the lower the S-meter reading. S/N ration is more important than meter readings.

  • @glennstevenson6242
    @glennstevenson6242 3 ปีที่แล้ว +1

    Great info. Thanks.

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว

      Glad it was helpful!

  • @frankENZC
    @frankENZC 3 ปีที่แล้ว +2

    Great video. I appreciate it! I subscribed! I cant wait to get back into the hobby. Been a Ham since 1971 and just got my Extra, December 2020. Cant wait to use the new license! 73 de WA3RSL.

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว

      Welcome back! I was AWOL for a few years. I might have averaged 4-5 contacts per year for around 12 years. I became more active a few years ago. Then I got involved in Summits On The Air (SOTA). Talk about putting amateur radio to the test. The blending of hiking, camping, and off-the-grid radio is addictive. It’s also good for my health.
      If you haven’t seen my SOTA videos, they are available on the channel. Look for the SOTA playlist.
      Thanks for subscribing and again, welcome back!
      73, de N4HNH

    • @frankENZC
      @frankENZC 3 ปีที่แล้ว

      @@n4hnhradio Thanks! I look forward to a new station, this year, I hope.
      73 de WA3RSL.

  • @GMGB68
    @GMGB68 3 ปีที่แล้ว +3

    Thank you for the video! It would be interesting to make the same test during a big CW contest. If I'm not wrong, the roofing filter acts over RF, and the DPS, only over AF. I mean, In a very crowded contest situation, that's where I think the roofing filer should shine, protecting the receiver from strong overloading signals that are near your operating QRG. 73 de EA6AMM

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว +2

      Welcome! There are numerous videos on the channel that deal with QRM from signals close by in frequency. If you spend enough time watching videos on this channel, you will see many.
      The roofing filter acts like another bandpass filter. But, instead of passing the entire spectrum of a band (i.e. 7.0 to 7.3MHz), it passes a narrow portion of spectrum at the IF (Intermediate Frequency) stage; after the first conversion. With the FTdx5000MP, the roofing filter is operating in the 9MHz, 1st IF, stage. In this video, the roofing filter helps the DSP by filtering down to a 300Hz bandwidth. This means the DSP doesn’t need to work so hard, so it does a better job of minimizing noise and interference.
      Note that a SDR has no roofing filter because it is sampling the signals directly at radio frequencies. There is no Intermediate Frequency where a roofing filter can be inserted into the signal chain. The FTdx101D, FTdx101MP, and the FTdx10 feature a dual-superheterodyne receiver along with a SDR stage, allowing those transceivers the opportunity to benefit from the selectivity of a superheterodyne receiver, with very effective 9MHz roofing filters, while still benefiting from the spectrum analysis provided by the SDR stage. Yaesu calls this “hybrid” technology.
      The DSP in the Yaesu FTdx5000MP is an IF DSP. Most transceivers today use IF DSP. I posted two videos a few weeks ago that show AF DSP, using an external DSP unit. Look for a video entitled, “Hello Old Friend!”
      73, de N4HNH

    • @GMGB68
      @GMGB68 3 ปีที่แล้ว +1

      @@n4hnhradio Thank you very much for the very complete information :-) I'll watch the other videos in your channel to learn more! 73, EA6AMM

    • @GMGB68
      @GMGB68 3 ปีที่แล้ว +2

      @@n4hnhradio Hi AGN! I just watched the "Hello old friend!" video, and I soon recognized him :-) It's sitting over an old friend of mine, my first HF rig, a Kenwood TS-850 :-) 73, EA6AMM

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว

      While the FT-890 is only an up-conversion transceiver, it still holds a special place in my shack. First HF transceiver I purchased. It suffers a bit from phase noise, as did transceivers from that age, but the sound quality of the receiver is awesome. Adding the DSP-59+ allowed it to compete with much more expensive transceivers at the time. And it is still no slouch, as the video shows.
      There is a second video with the DSP-59+ connected to the FTdx10. You can watch it to compare AF DSP to the latest in IF DSP.
      Thanks for visiting my channel!
      73, de N4HNH

  • @staceysmith2697
    @staceysmith2697 3 ปีที่แล้ว +1

    If you have the Yaesu FTDX10 you can buy the 300hz filter @ HRO the filter is a user plug & play filter. Ordering me one tomorrow. Great FTDX10 videos & others.
    73, W5MUT.

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว +1

      I like the 300Hz roofing filter in my FTdx5000 but the DSP filter does such a great job, the 600Hz roofing filter is effective enough.
      The FTdx10 comes standard with a 500Hz roofing filter. But it only needs to serve as a “rooftop”, then the DSP can take over and narrow down to 50Hz.
      If you plan to operate CW without using the DSP filter, then yes, the 300Hz roofing filter will be very beneficial.
      73, de N4HNH

  • @n1rbd
    @n1rbd 3 ปีที่แล้ว

    Bens Best Bent Wire/4 at 08:50!

  • @SteveG4YTK
    @SteveG4YTK ปีที่แล้ว +1

    Hi Doug do you think what pitch you choose matters. Is it down to your own ears ? I keep trying different setting, but I think 620hz works better for my ears ?

    • @n4hnhradio
      @n4hnhradio  ปีที่แล้ว +1

      I like the sound of 550 for rag chew but I can hear 600 better when pulling someone out of the noise. But that’s just me. I do think it’s a personal preference.

    • @SteveG4YTK
      @SteveG4YTK ปีที่แล้ว +1

      Thanks Dough for your thoughts
      @@n4hnhradio

  • @ralphnunn3
    @ralphnunn3 ปีที่แล้ว +1

    Man, I'm glad I ran across this video. I own an FTdx-1200. I know that the APF has been a godsend for me being a newer CW operator (3 years now...). I never knew where in the receiver chain it was implemented. Now I know! Also, I don't think the APF is adjustable on the 1200. But, it helps regardless... DE K7RLN

    • @n4hnhradio
      @n4hnhradio  ปีที่แล้ว

      Menu 107 in the FTdx1200 is where you can set the APF to Narrow. That’s how I run it.
      73, de N4HNH

  • @JxH
    @JxH 2 ปีที่แล้ว +1

    The roofing filter should have a larger dynamic range than a DSP, so it could potentially reject a very-nearby QRO station better than DSP alone. Of course, the entire receiver chain needs to have enough upstream dynamic range to support this theoretical improvement at the IF stage. This topic will inevitably get muddled, because DSP systems might move to (for example) 24-bit depth thus providing incredible dynamic range, the rest of the receiver chain may fail to have enough hardware dynamic range to support the advantage of the hardware roofing filter, etc., etc. Best evidence would be the consensus opinion of hard-core contest operators (assuming that they can reach a consensus). Facts will change over time as technology changes.
    P.S. I wonder if the 300 Hz filter is not "crystal" but perhaps 'mechanical' (i.e. Collins).

    • @n4hnhradio
      @n4hnhradio  2 ปีที่แล้ว

      Yaesu has used Collins in the past.

  • @fullsaildigital
    @fullsaildigital 3 ปีที่แล้ว +1

    Do I really need a 1.2khz ssb filter for my 101? I just don’t see how it can be intelligible that narrow. Especially when the dynamic range and the blocking is that good already!

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว +2

      I don’t think the 1.2 kHz SSB filter is absolutely necessary either. I can press the NAR button on my FTdx5000MP and it will allow me to vary the DSP filter width for SSB between 200 Hertz and 1.8 kHz. I have used it at 1.1 kHz before, to combat contesters moving in on my QSO. The DSP does a good enough job that I don’t think the physical filter is necessary. I can understand what the other station is saying at 1.1 kHz but their audio is very thin. But, when I must, it’s nice to know that I can. But, again the DSP can handle it.
      73, de N4HNH

  • @straightkey
    @straightkey ปีที่แล้ว

    I have the ftdx 3000 and I'm thinking it would be wasted money on my part. Thanks for the video.

    • @n4hnhradio
      @n4hnhradio  ปีที่แล้ว +1

      A tighter roofing filter helps the DSP stage do a better job. The more noise/interference you deal with in the early stages of the receiver assists the DSP and improves the overall performance of the receiver. I illustrated this in the FTdx10 series after installing a 300Hz filter. There was a noticeable improvement with the 300Hz filter, versus the sock 500Hz filter. But the FTdx3000 performs well, compared to many competitive transceivers. The tight filter can make it even better. It's like "icing on the cake."

    • @straightkey
      @straightkey ปีที่แล้ว

      @@n4hnhradio thanks for the input. I may have to reconsider now. 73

    • @n4hnhradio
      @n4hnhradio  ปีที่แล้ว +1

      I advise people that, if they only work CW casually, don’t worry about maxing out the filtering. If CW is your main interest, definitely max out and do it while the filters are still available. Yaesu sometimes discontinues the filters before they discontinue the radio. That happened with the FT-818. That’s why I maxed out the FTdx10 ASAP.

    • @straightkey
      @straightkey ปีที่แล้ว +1

      @n4hnhradio I use cw 99% of the time, so I suppose it would make sense to do what I can to make the operation more enjoyable. We'll, you talked me into it. By the way, my call is KT4RH. Maybe I can work you someday.

    • @n4hnhradio
      @n4hnhradio  ปีที่แล้ว

      Well, I don’t want to talk you into anything. I don’t work for Yaesu. I don’t even have a great relationship with Yaesu. I use their radios simply because they offer the most for my money.
      But, having been a purchaser of amateur radios since 1982, I have learned some lessons along the way. If you think you will want the accessories for a radio that you think you will keep, buy them while they are available. I regret not buying the optional TCXO for my FT-890/AT and my FT-920. They haven’t been available for years and years. Those transceivers tend to drift off frequency a bit. Fortunately, I know how to align them.

  • @peterolsen3886
    @peterolsen3886 3 ปีที่แล้ว +1

    Sorry if this is a bit off-topic. I hope to be able to buy a radio this year, but I can't decide on which one to buy. I'm thinking either the FTDX5000MP Limited with the three mu-tuners and station monitor or a used FTDX9000MP with all three mu-tuners and the DMU-9000 build-in. This wil be my first radio so both of them are beyond my skill level, but I want either of these two radios. I plan on keeping it for many years, so this is also an investment for the future. Anyway, the FTDX9000MP and the FTDX5000MP seem to be very similar radios. Does anyone know how these two compare? What would be the pros and cons of either?
    Thanks for any help

    • @fullsaildigital
      @fullsaildigital 3 ปีที่แล้ว +1

      I say 5000. Newer radio and a VERY good one at that. I don’t think you would notice a huge difference between the two

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว +1

      The FTdx5000MP is the latest design in that realm. I found the ergonomics of the 5000 to be better. The knob placement makes more sense than on the 9000. I know a guy with a 5000, a 9000, and a FTdx101MP. He says he still prefers the 5000.
      I believe the 9000 and 5000 will be phased out in the not-so-distant future. So, if you are going to get either of those, I would recommend that you do not delay. The 3000D had been discontinued, due to supply chain issues. The 5000 and 9000 are only available now by special order.
      I believe the 5000 to be the finest radio ever made.
      73, de N4HNH

    • @peterolsen3886
      @peterolsen3886 3 ปีที่แล้ว

      @@n4hnhradio Thanks turd and Doug. I did notice some oddities with the button and knob placement on the 9000, but I can live with that. One thing I like about the 9000 (the one without the build-in TFT display) is that it has more didicated knobs than the 5000 has, which I like. However, since this will be my first radio, this is just theory for me. Maybe it doesn't matter that there are multi purpose knobs on the 5000. Another thing I like about the 9000 is that it has more meters, but again, maybe this doesn't matter at all. what is your thoughts on this?
      If you have tried your friends 9000, what do you think of it?
      As you can probably tell, I am inclined towards the 9000MP with build-in mu-tuners and DMU-9000, but they are hard to find and a bit expensive. However, it is important for me to make an informed decission about this as I think this might be my first and last radio. I don't care much for software defined radios and I care even less for menu driven interfaces and bling (waterfall etc), and since this is the direction everyone seems to be going, I probably won't buy a new radio anytime.
      Thanks to all who replies and help me make up my mind

    • @n4hnhradio
      @n4hnhradio  3 ปีที่แล้ว

      @Peter Olsen, I can confirm that the knobs on my 5000 all have one dedicated purpose. I don’t care for menu-driven radios and multi-knobs, though I do tolerate the multi-knob on my FT-891, given it’s portability. The reason I like it better than the 9000 is because the knob placement makes more sense on the 5000.
      73, de N4HNH

  • @quadplay2591
    @quadplay2591 ปีที่แล้ว

    your demonstration is slightly flawed, the mechanical filter has better RF rejection on it's skirts. Whereas the DSP will reject out of band signals, it wont be as effective. So you need to do that test in a crowded CW band with strong adjacent signals... then the mechanical filter will shine.

    • @n4hnhradio
      @n4hnhradio  ปีที่แล้ว

      th-cam.com/video/9xELx2rGh3o/w-d-xo.html