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Author Topic: FTDX-101 20m signal image on 32Mhz?.  (Read 249 times)

ZS5WC

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FTDX-101 20m signal image on 32Mhz?.
« on: March 11, 2023, 08:41:02 AM »

Has anyone else seen this on the FTDX101?.
Seems like an 20m image on 32Mhz?.

https://m.youtube.com/watch?v=O0bH5DVl1Lw
73 de William ZS4L / ZS5WC
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WA2JHS

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #1 on: March 11, 2023, 10:03:01 AM »

yes...my ftdx 10 did the same thing....
73
Bill
Wa2jhs
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KX2T

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #2 on: March 11, 2023, 01:16:32 PM »

I think there is something to be said when looking at the specs of the FTDX101D/MP it states that the published specs are for Amateur Bands Only. The way I would translate this is that the radio is mainly a ham band only for its outstanding performance and that it may receive from almost DC to 70Mhz its not designed for best performance in the SWL/lower VHF spectrum.
 In my book if I wanted a decent SWL/Ham band radio I would buy a 7300 but been there done that, I would rather have balls to the wall HF Ham bands top performance then even care about SWLing. I myself would prefer that these current HF radio's design just for the ham bands and give optimum performance there.
 I had a 7300 and then the 7610, when 40 meters just around sunset would really started to open up and you would tune above 7.3 the SWL broadcaster would all me over +40db over and sometimes higher  in signal strength without any pre amp engaged in which the only bands I use the built in pre amp is when 10&15 just start to open up. Back to 40 meters at night and if your would tune the 7610 around 7.150 +- you would hear rather loud spurs and I men at S9 or over. Engage the Digi Select and it would drop about 2 s units and place another 20db of attenuation and it was still there. IMO Icom was more interested in making a HF spectrum radio then Ham band were both the FTDX10 I owned for 9 months and I have had the 101D for way over 1 year have had no spurs or issues in the ham bands. I  have looked night over night and the only thing I will see but do not hear at all is sometimes only on the spectrum scope I will see a signal pop up only on one sideband but there is no audio signal at all this is becaause the section of these rigs to give you the sdr display is nowhere near what the superhet/sdr section gives you. BTW put the VC tune on the 101D and that signal disappears on the spectrum scope.
 I know the next bitch will be is that you paid almost $4K or more for this radio why doesn't it work better on 32mhz well like I said before if you wanted a better HF amateur band  radio well these rigs give you that but honestly if you want swl radio there are literally tons of radio's for not allot of money that will give you those frequencies. It comes down to a mater of choices, my money is on BEST ham band performance and I do believe Yaesu has done this well.
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KX2T

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #3 on: March 11, 2023, 01:28:05 PM »

BTW I watched the video and frankly are you kidding plus the comment below about flagship radio sell sell sell is absolutely ludicrous. I use 10 metes and 12 gives me an indication if 10 might be open, 32mhz is way removed from 10 and not even anywhere near 6 so tell me why is 32Mhz important or do you just want to have a bitch fest on one of the better rigs out today.
BTW image rejection specs on this radio is for the ham bands only, they do not spec image rejection on anything else so maybe if this bothers someone question the company before you buy and ask them if there specs are basically for ham bands only or all of HF plus VHF. I have looked for junk signals that not only pop up on the spectrum scope but also ones that you can hear on every HF band plus six and there I have seen nor heard nothing with an antenna connected.
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KX2T

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #4 on: March 11, 2023, 01:32:00 PM »

BTW if you really don't like the 32Mhz thing I'll give you a hundred bucks for the rig if its all that band! LOL ;D
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G4AON

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #5 on: March 12, 2023, 04:58:48 AM »

By using a low first IF (8 or 9 MHz) you have the advantage of a high close in dynamic range. Plus being able to see “how much better the radio is” compared to some others on Rob Sherwood’s list… the downside is poor image rejection compared to radios with a much higher first IF (typically up to 70+ MHz). The choice of a high/low IF is a compromise depending on whether you want better dynamic range or image rejection.

Normally in a low IF amateur transceiver you run the VFO on the high side and receive through the TX low pass filter. The image is then 2 x the IF away on the high side of where you are listening. Image rejection is enhanced by the TX LPF.

My guess, and I haven’t checked, is that above 30 MHz the 101 runs the VFO on the low side resulting in images 2 x IF (18 MHz) below the dial frequency where any TX low pass filter is not effective.

I would be more concerned if you receive images of 10 to 12 MHz on 10m.

Plus, as others pointed out, the spec will only be valid in the amateur bands.

73 Dave
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ZS5WC

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #6 on: March 12, 2023, 09:47:00 AM »

 :)Interesting comments and very interesting there Dave.
No , I'm not bitching about the rig, I just thought the anomaly was an interesting one, something I had not seen before.
Does that mean that these rigs don't have receive bandpass filters ?. Obviously that filter for 20m would not be selected at 32Mhz?.
Perhaps if VFO2 wasn't selected , that BPF for 20 would not be selected, or do they rely purely on the Preselector?.
AS you pointed out, as long as the unwanted signals don't appear within the Amateur Bands.
73 de William
ZS4L  ZS5WC
 
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AC2EU

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #7 on: March 12, 2023, 11:17:18 AM »

:)Interesting comments and very interesting there Dave.
No , I'm not bitching about the rig, I just thought the anomaly was an interesting one, something I had not seen before.
Does that mean that these rigs don't have receive bandpass filters ?. Obviously that filter for 20m would not be selected at 32Mhz?.
Perhaps if VFO2 wasn't selected , that BPF for 20 would not be selected, or do they rely purely on the Preselector?.
AS you pointed out, as long as the unwanted signals don't appear within the Amateur Bands.
73 de William
ZS4L  ZS5WC

maybe the spur is from the control /display harmonics?
 

W1VT

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #8 on: March 13, 2023, 05:49:13 AM »

Typically the ham radio market is so price sensitive that only ham band RF BPFs are available, even if you are willing to extra for general coverage filters.
But, the now obsolete Elecraft K3 had the KBPF3 filter option, which included those missing general coverage filters!

https://elecraft.com/pages/k3-non-s-version-manuals
see page 45
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G8FXC

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #9 on: March 13, 2023, 07:35:56 AM »

... 32mhz is way removed from 10 and not even anywhere near 6 so tell me why is 32Mhz important or do you just want to have a bitch fest on one of the better rigs out today.
...

The potential problem is that the images extend to 40MHz - which is slowly being released to European hams. But Yaesu are quite clear about it - performance only guaranteed in the ham bands as they were when the radio was designed!

Martin (G8FXC)
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G4AON

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #10 on: March 14, 2023, 07:26:50 AM »

Further to my last post, I have checked the RSGB RadCom October 2019 review of the ‘101, and as I suspected, the oscillator runs on the low side above 30 MHz resulting in picking up the 20m image frequencies when tuned to 32 MHz, as mentioned in the original post.

Rather a strange configuration, but the manual states the spec is only applicable within the amateur bands.

73 Dave
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K6BRN

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #11 on: March 14, 2023, 10:48:57 AM »

Hmmm.  Why does anybody think this is news?

Amateur radio transceivers are always opimized for ham band use at the expense of general coverage, which is a "bonus feature" that simply didn't exist in older tube sets and many (especially earlier) solid state rigs.

Even radios designed for "general coverage" have images/spurs/etc., especially when covering five octaves (or more) of frequency bands.  Compare the the optimizations of the older Kenwood R5000 and TS-440S.  They LOOK the same, they FEEL the same, but the R5000 is a much better general coverage receiver, just as the TS-440S is much better on the ham bands.  Both can RX images of very strong signals (used a TS-440S for years), though not as much as a downconverting receiver, and spurs (galore), despite the TS-440S 45 MHz (upconverting) receiver and the R5000's 58 MHz IF.  But NOT so much that it's a real problem.

Drake introduced upconverting, general coverage receivers in its 7-series (1978/79) transceivers to reduce images, at the expense of filter performance.  Now we're back to downconversion for it own (close-in signal rejection/filtering) benefits on ham bands.  OK.  Fine.  Both work and have slightly different benefits.

Regarding the FTDX-101D/MP ... a nice amateur radio transceiver, period.  The O.P. of this thread simply noted one artifact that can be found across its RX range.  That artifact is not the only one.  Yet it's amateur band performance excels.

No worries.  A lot of amateurs still like their upconverting radios, too, like the FTDX-9000 crew.

Brian - K6BRN
« Last Edit: March 14, 2023, 10:53:10 AM by K6BRN »
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W1VT

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #12 on: March 14, 2023, 11:38:02 AM »

I built a little receiver accessory box for my Ten Tec Argonaut to fix some receive issues.
When I lived in Honolulu I realized that I had some receive issues from line of sight AM broadcast, so I added bandpass filters for 10 and 15 meters.
I also added an RX preamp, switchable adjustable resistive attenuator, and a RX input connection.

Zak W1VT
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KA4WJA

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #13 on: March 18, 2023, 09:55:47 PM »

Gosh, a radio that is not perfect?  Next thing we'll be discussing is gambling in Casablanca?  Hi hi

Guess it won't come as a surprise that I agree here with most of what Jim, KX2T and Brian, K6BRN, wrote.
But, I wish Jim would tell us what he really thinks.  :) hi hi (good to hear from you Jim!)

And, a big thank you to Dave, G4AON, for giving us some rig-specific details.  Thanks!

Yes, I'm usually the guy taking about the other half of the radio ---- the transmitter!  But, guess I'll spend a few minutes commenting on the half that everyone else concentrates on.  :)


Yep....I'm one of those that prefer my old 1970's tech "up-convert" radio, the Drake TR-7....debuted for sale in early 1978, when I bought my first one (bought a second one, an early 1979 model, about 20 - 25 years later)....and continued in production 'til early 1983, with a total of ~ 12,500 made...the last 18 months of production / the last ~ 2000 units, being the TR-7a models, which are identical except they came equipped with some original "options" (noise blanker and CW filter) as standard, and had an "input surge protection" circuit added, as well as having transmit mic signal input routed to one of the two "spare" RCA jacks on the rear panel, simplifying RTTY/FSK hook-ups.

This ole' venerable rig was designed in the mid-1970's....starting about the time the "C-line" came out (mid-1973) Drake's chief design engineer (Milt Sullivan, K8YDO) started to look at designing their next rig (the TR-7), and he hired the gentleman that had just designed the Heathkit SB-104, to help him and his team....and from 1974, or so,  R.L. Drake with Milt and his team, went onto to create what would turn out to be a revolutionary radio, the TR-7....the IC-7300 of its day!  :)


Yes, yes....I'm a TR-7 "fan boy", but I'm not a new-comer to the TR-7....bought one new in 1978.
And, I am a realist, I admit that by today's standards (50 years on), the TR-7's VCO's are noisy, its PTO (vfo) does drift upon start-up and the first 10 minutes or so....and, as for "modern features", it has no memories, only one vfo (needs the optional external vfo, to run "split"), no DSP, no "band-scope", etc...
But, it's transmitter is wicked-clean....will run 150 watts out 100% duty-cycle, etc...and, aside from the above old design issues, its receiver holds its own against many modern 21st Century rigs.

About the only thing that "modern" tech could improve on this venerable beast is lower phase noise VCO's (ya' know there have been many scientific / engineering improvements in the ~ 50 years since it was designed), and none other than Ulrich Rohde wrote about this upgrade regarding some other radios of this era, and if I was interested in serious CW contesting (where close-in RMDR and close-in IMD3 was critical), I'd buy a replacement VCO board and make some changes, and try it out....but I'm not much into CW, and certainly not into CW contesting, so no worries with the TR-7!  :)
{oh....it's unlikely, but "possible", that changing the mixer and 1st IF amp to some more modern parts might help a tiny bit....but, unless the VCO's are changed, this would be a waste....especially since the TR-7's "up-conversion" uses a high-level DBM and a low-noise JFET 1st IF (48mhz) amp, producing a very sensitive front-end (MDS = -134dbm) without any RF amp / pre-amp!  So, the only major issue is the 50-year-old VCO's. }


Here's just a brief description of the TR-7's receive front end, too bad some of our new/modern rigs aren't similarly designed (with new/modern components)...from the TR-7 manual:

Quote
Incoming signals from the antenna pass through a band-switched low-pass filter module. the transmit / receive antenna switching, and a band-switched high-pass filter module [and, these filters are low-loss air-wound coils and silver-mica caps....oh, and band-switched hi-pass filtering is something many "modern" ham rigs do not have, leaving even more ways for issues to occur. :( ]. These filters create an in­put bandpass filter.  The limits of which are defined by the yellow numerals on the front panel BAND switch. A separate receiver and/or receive antenna can be connected in this path by removing the jumper between the EXT RCVR and EXT ANT jacks on the rear panel and making the appropriate connections.

The output of the high-pass filter is connected to the input of the Up-Converter module, along with the VLF antenna input and the 25 kHz calibrator output. The VLF antenna is connected through a 20 dB attenuator due to the fact that the input an­tenna filters are bypassed by this input. [this attenuator also reduces your VLF transmit output by 20db...so, 630m and 2200m operation is 20db lower, unless bypassing this internal attenuator....something I may do, as the harmonic output of the TR-7 on 630m and 2200m is within FCC spec as-is, how about that from a ~ 50 year old design....so who knows...]
Signals at the input of the Up-Converter module are mixed with the output of the synthesizer VCO to create a 48.05mHz  intermediate  frequency (IF) signal. Conversion is accomplished by a high-level, double balanced mixer to provide a very wide dynamic range.  The output of this mixer is amplified by a low-noise, high dynamic range junction FET amplifier to insure adequate receiver sensitivity. This stage is followed by a four-pole monolithic 48.05mHz crystal filter. The purpose of this filter is to attenuate signals removed more than +/-4 kHz from 48.05mHz. thus protecting the remaining stages of the receiver from strong interfering signals.
In this manner, optimum receiver dynamic range is pre­served while providing excellent sensitivity.
[Some have opined that retuning/narrowing, and/or adding more poles to this 8khz wide, 4-pole "roofing filter" would improve the TR-7's "close-in" receive IMD3 spec, which it would do....but, unless changing the VCO's, you'd still be "noise-limited" i.e. this would not do much to improve the RMDR.
As narrowing this "roofing filter" (1st IF filter), as well as adding further poles, would change the shape of noise pulses, which would require realignment (and possible redesign?) of the TR-7's excellent noise blanker (the NB-7, which was a ~ $75 option in 1978 ($90 in 1979), which is ~ $350 - $370 dollars today, just for the noise blanker!), and since changing the VCO's would go a LONG way to making the 50-year old design of the TR-7 compete quite well with 2020's design rigs, this (the VCO's) would be the first thing to upgrade...and then adding switchable narrower 1st IF filters, and a "new & improved" TR-7 would find itself floating up towards the top of "the list"....okay, it might not ever be at the top, but darn close, hi hi]
 

In 1979, a TR-7/DR-7 with NB-7, a couple narrower 2nd IF filters, etc. was ~ $1595 list / ~ $1450 - $1500 "street price"....That's a "street price" of about $6200+ in today's dollars!
Plus an addition $175 (in 1979 dollars) for the remote VFO...so, that's almost $7k in today's dollars, all-in!


 
And, have a look below, and ask yourself, how many "modern" amateur radios' manuals discuss the radio and its design like this?
Heck, how many RF design engineers discuss these things at all, anymore?
Maybe the guys at Apache Labs do, but I suspect few, if any, others....(maybe, just maybe, the boys at Elecraft...but doubtful they proceed with much that isn't something "whiz-bang" they can "sell" to the contester crowd?)

Milt Sullivan [K8YDO], et al, at R. L. Drake took great pride in the design and engineering of every system / part in the radio [TR-7]....you think "YaeComWoodFlexCraft" has even one guy/gal that even cares enough or has the smarts to do that?
Doubtful, but even if they do have someone that good on staff, are they given the time and authority to actually make a radio, noise blanker, etc., that is as good as ones made > 45 years ago, I highly doubt it.
Which is why we get the radios we get these days, fancy yes, great lab test results yes....but fun and easy to operate, hmmm, the jury is still out on that! :)

Here's a quote from the TR-7's manual, discussing just the NB-7 Noise Blanker (and, this is just ONE circuit):
Quote
Circuit Description:
    This noise blanker system is comprised of the three major networks described below. Refer to the proper schematic for your particular version to follow this description.

    Transmit Path
    In transmit, diode CR815 is turned on with +10T via RFC812 and RFC813 from pin 37. The 5.645 MHz double sideband transmit signal is fed to the output coax connector through C833, CR815 and C838. When CR815 is on, CR814 will be reverse biased, thus holding the receive path off.

    Receive Path
    In receive, diode CR814 is turned on with +10R via RFC810 and RFC811 from pin 24. In version 1, the receive signal is applied to pin 22 and coupled directly to the blanking gate, comprised of T810, CR812, CR813, and T811, then through C830, CR.814 and C838 to the output coax connector. In version 2, the receive signal again enters from pin 22, however, then passed through a matching amplifier consisting ofQ816 and associated circuitry. The output of Q816 is then coupled to the blanking gate of T811, CR812, CR813 and T811, passes through C830, CR814 and C838 to the output coax.

    Noise Processor
    The Noise Amplifiers consist of Q810, Q811, and U810 cascaded and tuned to 5.645 MHz by L810, L811 and L812 respectively. The output of the noise amplifier string is split by C828 to the pulse detector and C827 to the noise amplifier AGC circuit. Q812 and associated circuitry comprise the noise amplifier AGC detector and amplifier. The AGC voltage is applied to gate 1 of Q810 and Q811 via R826 and R829 respectively.

    The pulse detector, CR811, responds only to the positive half of the amplified bipolar input pulse. The network of R839, C831 and C835 wave shape the pulse at the base of the pulse amplifier QB 13. Again, the output pulse of Q813 is shaped by R847 andC840 and is applied to the gate driver, Q814. Resistor network R842 and R843 provide fixed reverse bias for the blanking gate. Q815 is a DC switch for +10R and +10NB.


    Theory of Operation
    The 5.645 MHz receive signal, with noise pulses, is applied to pin 22. In version 1 this signal is coupled directly to the blanking gate. In version 2, amplifier Q8I6 amplifies the signal and noise pulses to drive the blanking gate. Tuned amplifiers Q810, Q811 and U810 amplify this low level signal up to a high level to drive the pulse detector CR811.

    This detector responds only to the positive going portion of each noise pulse from the output of U810. Following the detector is an RC network which shapes the pulses for driving the level shifter Q813. Again, on the output of Q813 is still another RC network for wave shaping. The gate driver transistor Q814 responds to the negative going pulse from Q813 which allows the blanking gate to tum off, thus muting the receive path and blanking the noise pulse.

    Since the noise amplifiers run such high gain, Q812 and associated circuitry comprise an AGC loop to maintain a near constant output level to the detector. This allows detection and processing of very weak as well as very strong noise pulses without degrading the blanking action.


Now, some are saying...."huh?  What is this guy spouting off about?  This is a thread regarding a perceived issue with a FTdx-10 image issues when operating way out-of-band, why is he off on Drake TR-7 fan-boy advertisement?"
Well...

Well, the answer is....to show you all that there is no "perfect radio", and to try to compare one designed for one purpose / in one era, to others designed for different purpose/different era, is sort-of a waste.  :)  hi hi
And, Brian went to the Kenwood 440 vs. the R-5000, to make a point, and Jim compared the Yaesu's to his old '7300 and '7610....so, I'm just a bit more long-winded.
 
But, if some also gain a new respect for an almost 50-year-old TR-7, well that's a nice secondary plus.  :)


73 to all,
John,  KA4WJA
« Last Edit: March 18, 2023, 10:10:12 PM by KA4WJA »
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G8FXC

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Re: FTDX-101 20m signal image on 32Mhz?.
« Reply #14 on: March 19, 2023, 01:57:48 AM »

Gosh, a radio that is not perfect?  Next thing we'll be discussing is gambling in Casablanca?  Hi hi

...


73 to all,
John,  KA4WJA

Well, as I said above, I don't think we would be remarking on it at all if it were not for the fact that several countries are now beginning to release a spectrum allocation around 40MHz to the ham population. The howls of anguish that I've heard regarding the FTdx101 series of radios have all come from a couple of Irish hams who are amongst the first in Europe to have permission to operate 40MHz and are hearing stations on 20m as they tune around there. Yaesu, of course, made no commitment that the radio would be usable on those frequencies - it's just unfortunate that the band allocation has only recently been made and nobody had bothered to check the performance of the radio around there. I have to admit that it came as a surprise to me that it would actually tune to 40MHz.

Martin (G8FXC)
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