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Author Topic: A different version of the IC7300 or FTDX3000 question - no contesting  (Read 1055 times)

K6BRN

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Hi Peter:

I don't think I'm overestimating the MTUs.  They BEGIN to make a difference on a strong signal that is pumping the AGC, IF that signal is at least 8 KHz away from the signal of interest AND the MTU is tuned to take advantage of its broad skirts, by placing the interferer as deep into filter rolloff as possible before the signal of interest is attenuated too far as well.

I use them a lot and have characterized them (see link to my review, below).  There is a learning curve - the MTUs are NOT like the active preselectors found on tube rigs (and even some early transistor transceivers) in that they are totally passive and very broad.  So it takes some finesse to get the best out of them.  But their strength is that they are tunable AND come before the preamps and AGC.

BTW, I've learned how to use them a little better than when I did the review.  Still, they are not miracle filters, but when used in non-obvious ways, they do provide some help, even in band, per my first paragraph above. 

https://www.eham.net/reviews/view-product?id=7949

Brian - K6BRN
« Last Edit: July 09, 2020, 12:44:15 PM by K6BRN »
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KX2T

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Brian  you are right on the money as far as the 3000 having lower noise floor in the IPO position then the 7300 with no pre amp but looking at the lab numbers of the 3000 in the IPO no pre amp and then to the 7300 W/O pre amp there is a real difference in sensitivity. The 3000 is at -127db and the 7300 at -133 db so to compare radio to radio in noise floor you would have to place the 3000 at Pre Amp 1 which is -138db and then use 6 db of attenuation, then you will have a closer comparison. The one thing Icom didn't do is add a three step attenuater but that could be calculated on the RF gain control, when owned both yes the high frequency audio response on the Yaesu was and could also be rolled off so that also makes it seem more quiet. Judicial use of the NR on the Icom almost does the same thing but when you look on a scope it does reduce the noise component extremely well even when the level has been brought up allot with no under water DSP artifacts. I feel there is a real need for either company to look at the $2K price range radio with up graded features and who knows maybe Yaesu might dive into the SDR market cause although the FTDX101 has a soo called SDR back end the front end is still a superhet, a dam good one at that but they need to look closer at Icom's DSP/SDR development, even Flex is lacking in this area but as history has shown Icom started very good DSP development way early on.
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K6AER

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Your noise floor is determined by the antenna. Even a 50 years old 75A4 is better than a typical antenna noise floor by 20 dB.
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K6BRN

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Your noise floor is determined by the antenna. Even a 50 years old 75A4 is better than a typical antenna noise floor by 20 dB.

The antenna type, polarization and directional gain CAN affect apparent noise floor of an HF station.  But it's environmental noise, both man-made (A/C inverter drives, power lines, solar installations, etc.) and natural (like lightning strikes) that usually dominates in amateur HF applications and is variable from location to location.  If I were doing a G/T calculation at a fixed thermal noise temperature the antenna gain WOULD make a difference and this is a pretty important figure of merit in a thermal noise dominated environment.  This becomes important in EME communications at higher frequencies.  But not so much at HF.

Regarding quiet receivers, phase noise in earlier solid state receivers (like the ever-popular TS-440S) can make a significant difference, particularly its tendency to spread (widen) other noise sources across and into the tuned bandwidth.  Because of spreading during the mixing process, noise sources outside of the tuned bandwidth can be translated directly into the IF and AF filter pass-bands, which can make high phase noise receivers harsh to listen to, even if the phase noise by itself is not objectionable.  The bandwidth and amplitude of the phase noise in the synthesizer will determine how fatiguing this is to an operator.  Ironically, older tube and non-synthesized solid state receivers, like the Collins 74A4, have much less problem with phase noise can have a much "mellower" tone that is less fatiguing.

Both the Icom IC-7300 and Yaesu FTDX-3000 have relatively low phase noise compared to a TS-440S and also have fairly low distortion in their RX audio chain.  That combined with modern digital noise reduction, even at minimum setting, makes them relatively easy to listen to without fatigue.  Try listening to a TS-440S or similar vintage synthesized rig, next to an FTDX-3000 and you'll immediately hear the difference.  Or put the TS-440S next to an old Collins rig.

Brian - K6BRN
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HB9PJT

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I don't think I'm overestimating the MTUs.  They BEGIN to make a difference on a strong signal that is pumping the AGC, IF that signal is at least 8 KHz away from the signal of interest AND the MTU is tuned to take advantage of its broad skirts, by placing the interferer as deep into filter rolloff as possible before the signal of interest is attenuated too far as well.

https://www.eham.net/reviews/view-product?id=7949

Brian - K6BRN
Hi Brian, thanks for the link. There you write:
Quote from: K6BRN
Yaesu markets the MTU filters as providing “…ultra sharp RF selectivity for the front end of the transceiver”, and that is EXACTLY what they do, and they do it WELL, with a typical 6db bandwidth of 40-60 KHz ...
But that means, 8 kHz ffrom the signal of interest it may be down less that 6 dB since 40-60 kHz refers to 6 dB. If you see in that conext an improvement of the AGC it seems to me the AGC system in that TRX is not ok.

73, Peter - HB9PJT
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KX2T

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Hi Brian ,many years ago I owned the early Kenwood TS820 which was followed by the Yeasu FT901DM, now between those two radio's the specs did read better on the Yaesu yet the 820 seemed to have a lot less RX noise. Years later I bought a TS930S that entered a new phase for radio's, full RX coverage, many more selectivity controls but in the end a very noise radio because of there synthesizer have much higher noise added to the system. I also owned the 440S and that was nothing but a noisy  RX. There was something nice and simple about the early tube/ss rigs, they were ham band only, they didn't need to cover DC to light so there designs were less complicated plus the RX sections could be made with a lower noise floor of course phase noise did exist but these newer radio's are soo far ahead its not funny.
I look back at the last 30 years and a lot has changed, these newer radio's do soo much more with very nice sounding RX sections that would have cost tens of thousands of dollars back in those days but today anywhere between $1K to $12K you have a hoard of radio's to chose from.
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K6BRN

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Peter (HB9PJT):

I think we are talking past each other. 

The Yaesu MTUs are agile passive filters and it is possible and useful to adjust them to "ride the skirts" where both the signal of interest and the offending signal are attenuated - but the offending signal is deeper in the rolloff.  Note that deeper into the side skirts rolloff gets much steeper than the passband rolloff.  This BEGINS to be useful around 8 KHz or so - that's simply my experience, and unexpected. No one said its a great filter at that point for eliminating in-band interference.  But recall that the receiver bandpass filters are VERY wide, with the result that a LOT of out of band noise and interference makes its way into the receiver passband, pumping the AGC as well and absorbing dynamic range.  The MTUs are quite GOOD at suppressing THIS interference, which is prevalent when operating on 160M and even on the higher bands during events, like Field Day.

What I DID NOT expect is that they help significantly with FT8, most likely by suppressing (shaping) the noise floor a bit - just enough to make a difference in a marginal contact situation.  Still not miracle filters and expensive for what they are - even though I paid about 40% of list price. 

Again, this is based on direct learning experience with them.

Brian - K6BRN
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K6BRN

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James (KX2T):

Yes, I agree entirely.  I moved from an HW-101 to a Kenwood TS440S and gained a lot of stability and features (memory, better filtering, 10M repeater tones...).  But the TS440S was PAINFUL to listen to for long periods whereas the HW101 was not fatiguing at all.

And you're right - the modern rigs, even those at the lower cost points, have mostly cleaned up that problem.  Lots of good choices out there - which is why I often chuckle over "Which is the best rig?" questions.  (Answer:  The one you actually USE!)

BTW - I still have my old TS440S (had a lot of fun with that radio) and have found that if I run the audio into a West Mountain Radio CLRdsp noise reduction unit, the fatigue goes away.  But the CLRdsp, new, is about 50% (or more) of the value of the TS440S, so its really better just to get a more modern radio.

Brian - K6BRN
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KX2T

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Brian I didn't have the HW101 but had built the original HW100 which was my first real SSB xcvr so back then I thought it was the cats nuts plus a decent radio but after I came out of the air force I sold it to a ham friend on base and when I got home I had a friend who worked for Saxton wire and cable who sold me a Swan 500CX, the ssb rx was nice and smooth on the old Swan but had to buy a 508 VFO because of the drift on 10 meters was horrible but after a few years I ended up trading the ole Swan in for a Drake TR4, then the TS520, then an FT101E, then back to a TS520S, all very good rigs but the 820 was the first what most considered competition grade for its time next to a Drake 4 line or Collins.
Yes I have owned a few Yaesu radio along with the Kenwoods.
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K6BRN

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Hi James (KX2T):

FB regarding your journey from the HW-100 to the 820.  Sounds like a fun trip, with many more adventures than I've had.

The first radio (receiver) I built was a Heathkit HR-10B.  That was a terrible receiver with many issues.  But I had a lot of fun with it anyway.

When I had the chance to get a battered HW-101 and rebuild it, I was very happy.  And when completed, THAT radio was a dream come true.  It handled very well and was two quantum leaps beyond the HR-10B (and it transmitted!)  I still miss the HW-101.  Never got tired of using it.

Always lusted after the SB-104, though. And like many childhood dreams (cars, radios, etc.), I still do and have to slap myself eveytime I find one - because the last thing I need is yet more old radio equipment.  My CA home does not have a basement - and really needs one for this hobby.

Then I switched to a used TS-440S and was simply amazed at how stable it was and how easy it made running AMTOR and RTTY.  Not to mention memories and filtering choices.  While I made the occasional CW contact, it was not my preferred mode, and I was by now a new engineer working in the field of digital comms - and that passion carried over to amateur radio.  I did work SSB, but found the audio harsh no matter what I did.  Which pushed me even harder into the digital modes.

From there, I helped test and improve some early packet radio modems and eventually drifted away into starting a family.

Today, my stations are a mix of Yaesu, Icom, Kenwood and Elecraft gear, with a bunch of older stuff in the closet I've been trying to trim down.

Life really is a journey - and I'm happy to have survived this long to enjoy it.  Not all of my friends have been so lucky.  So I like to look back and appreciate where I've been and who I've lived life with, rather than regret what might have been.

Brian - K6BRN



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KX2T

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Brian, I remember friends who built that heath HR10B plus the DX 60 which was the poor mans version of the novice Drake station the 2C and the 2NT , now that was a cats nuts novice station in 68 and 69. The very first RX was a Lafayette SW RX which drifted like 10khz every half hour so you were constantly spotting your transmit frequency plus a two tube xtal transmitter made from TV junk parts with a whole 20 watts out on 40 meters, if you worked another state you were happy! Then the HQ100 which was a little better plus a night kit T60 and that could produce 60 watts almost the novice 75 watts input!
I found a Lafayette HA350 which was a dual conversion ham band only RX used that had a 2Khz mechanical  filter which was really a big upgrade from
the HQ100 and I do believe it was made by Panasonic back then so it felt and look really nice but once I got my general class I found a local ham who just purchased a HW100 kit and was excepted to a university in California, he said he would not have the time with school to build it so I bought the whole kit with PS for $200 from him, that was a real radio compared to the novice gear.
Yes it nice to stroll down life's fun times  plus I did go threw allot of Yaesu gear when I was hog wiled into contesting in the nineties, started with a IC751A but that radio could not handle doing M/S, the front ends would melt, then the FT990 which was the poor mans FT1000D and then I traded up to the 1000D but when the original MP came out and its second order IMD was over 80db well had to have that radio along with half my buddies buying the same rig cause they could be run in a M/s station without toast at the end for front ends. Today its a different world cause back then our radio's were only protected by coaxial stubs and the original ICE band pas filters, today you have plug and play devices that let you run a multi element tribander and run three stations with Kilowatts off one antenna system, so designing a station back then then would not toast the RX front ends on a 1/3 acre plot had taken allot of work, proper grounding and antennas had to be placed were they would not be too much interaction between bands but it could be done. As the old song says 'those were the day my friend I thought they'd never end" but alas they did.
I am very happy to have lived threw some very fond times with this hobby plus the friendships I have had with a few close ham buddies that keep that smile on ones face, I very much agree that appreciating what we all have had and done with not only the hobby but the good friendships we made along the way, No Regrets at all!
Jim KX2T
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