It does Brian. But a mechanical/crystal IF filter needs no power to operate just the power to the analog stages that it sits between. IF DSP filter is always going to be current heavy in comparison. Unless you are making bazillions of devices then you’ll end up with a software filter running on a DSP and these things are normally written to function with power consumption lower down the list of desires. Mobile phones (were you make millions and millions a week) will have dedicated DSP filtering done in hardware and will be optimised for both power and performance.
Our IF DSP requirements are not mainstream so we will normally be at an awkward point to benefit from what is available cheaply.
Hmmm. Its a long time since I built a receiver, but I seem to remember that mech/xtl filters produce attenuation making extra amplification necessary which reduces the power benefit. Its a pity that 85 or 50 KHz IF transformers (if available nowadays) would carry a weight and bulk penalty…but I have a few pot/core formers in the junk box and a spool of Litz (sp?) wire…
It is a hobby Ron, time has little significance in weighing up if something is worth doing because you are supposed to be doing it for fun right ?
I have to think in two minds about this now, what you do in a commercial sense and for amateur radio are two completely different things.
Don’t forget as you go lower in frequency Q factor becomes less significant. Richards suggestion to use ceramic resonators @ 455 kHz is a good suggestion. If you use a program such as AADE filter design you will be able to accurately determine if your design will meet the stop band and ripple requirements. If your hombrewing something from scratch I am surprised you have selected such a low IF in modern times you can get microprocessor crystals for very little money and build reasonable filters in the 8-25 MHZ range.
Building good ladder filters takes practice, but is hugely satisfying. If your building a high performance receiver I would not recommend cheap crystals as they can be a significant source of IMD. I once bought a set of eight crystals from QT costing in the region of £120 for a particular front end project.
IF DSP can give you a huge advantage, providing it is used correctly. If you look at Peter Rhodes work on the PICaSTAR project you may be able to appreciate this. Whilst DSP processing platforms do consume more power then the equivalent analogue signal chain hardware you buy some of this power consumption back in software gain.The main advantage with DSP is the ability to apply system gain in a more constructive way. You just cannot achieve this to the same system level with pure analogue systems. Conversely though you cannot achieve the same overall linearity with pure digital implementations - a balancing act.
Power consumption higher ? Look at the KX3 uses a ADSP21489 DSP and is currently one of the lowest power consuming portable radios available for its given functionality.
The argument for what can be done in radio amateur circles at the base-band processing level has already been clearly won IMO. We are now getting to the point where FPGA hardware is becoming cheaper and lower in power budget. Exciting times !
What a bargain, show them the colour of your money prevaricators! Not that I’m keen on that particular emporium having had problems with them in the past when they sold me a second hand filter for an FT-2000D and claimed it was new…
I paid £325 for a secondhand 7 years old FT-817 - 2 years ago… and the mic insert failed on me in Ibiza in September, otherwise its been a fabulous radio and has made 1000s of SOTA activator QSOs. Oddly enough I have never used the FT-817 in the shack where superior Yaesu and Icom radio’s are available…
WoW - that is a VERY good deal then, although as the price is only for online orders, whoever grabs one will need to take account of shipping costs on top, but within the UK, hopefully that’s not too bad.
66 Messages of speculation. Has anyone thought to just email Yaesu and ask them?
There were rumors of the 857 being replaced a couple years back and I emailed Yaesu and asked. They were nice and responded promptly. They said no. End of rumor.
Maybe some Yaesu R&D staff are secretly beavering away in the corner of a workshop in Japan designing a 10 watt SDR Transceiver which would overhaul the expensive Elecraft KX3. They were innovative enough to produce the fantastic FT-817 so why not? Us potential buyers will be the last to know if this is the case, but we will be queing up to buy one!
Whilst the FT817 & other current radios will no doubt still be produced for quite some time, it won’t be much longer before Collins mechanical filters go the way of the Dodo. I’m not sure if InRad are thinking of doing the same but this is sad for those of us who appreciate good filters
I purchased my FT817 second hand, did the TX expansion mod to give it 60m & the extra 100KHz of 40m we were given a couple of years ago & it is a superb radio, not only for its size but also when compared to much bigger radios. I could not believe how well such a small multi-band radio performed on 145MHz FM right next to the legendary QRM source that is G/SP-017 Billinge Hill.
I used to think 5 Watts was not enough, it’s more then enough with CW.
That said, this weekend is the CQWW DX CW contest so however much power you have, it may be a struggle to have a normal QSO at times
Yes it is a hobby but I learned long ago that if I wait until I have the time and inclination to build something instead of buying it I miss out on a lot of fun. I have a mixture of home-built and commercial kit. Do I want to build another ladder filter? Dunno. Can I do it in two days? Will it fit in the holes in the 817? Maybe. Or could I buy it and activate two peaks on those two days. Which would I enjoy more?
I don’t activate as much as I should, partly because I want to use a different configuration to the last time and that has to be cobbled together and tested before going bush. Maybe 25% of my “activations” are with instruments in the driveway.
I think you drifted off there Jonathon re 455 kHz. The thread had focused on improving the FT817 (we’ve given up on a replacement anytime soon) and one weakness is the final IF filter which is at 455 kHz. To improve it a replacement mechanical filter is the way to go with crystals the next best. The 817 uses a ceramic filter and when 20 m has a contest on and the band is open the inadequacies show up big time.
So I don’t think I can do a great job with ceramic filters. I know I can do a better job with crystals, if the price is right, which it isn’t.
DSP? Well better start from scratch, or buy a KX3.
(a) It would spoil the fun of speculating and daydreaming about what the replacement would do.
(b) I don’t think they would say “yes” until they were actually shipping it. Existing stock needs to go and a market need enhanced so there are plenty of buyers who will pay the initial price.
You said:“If your hombrewing something from scratch I am surprised you have
selected such a low IF in modern times you can get microprocessor
crystals for very little money and build reasonable filters in the 8-25
MHZ range.”
That’s the bit where I thought you made a diversion as the focus was on FT817 replacement filters not building a new high performance rig.
What I actually asked about was where I could get inexpensive 455 kHz crystals and you suggested QT in Germany and Euro Quartz. Thanks.
For SOTA activating, the the 817 is a great rig and will do “just about” everything the average Activator wants +/-
The 857 is an even better rig, if you’re prepared to lug the extra weight up and down summits …which most acivators are not. Both of these rigs have been around since the last ice age and with the exception of the inclusion of DSP, their specifications have changed little.
From a selling point of view, should you ever get bored with your 817/857, these are the two easiest rigs in the world to trade on. There are always buyers for them. A sensibly priced 817 or 857 at a rally, will usually be snapped up well inside half an hour. I wish I could say the same for many other rigs.
Looks to me as if Yaesu have taken the common sense approach, that if it ain’t broke, don’t fix it. Having said this, it has been my experience of ham radio, that common sense stands at a big premium.
Will there be a replacement/upgrade for these rigs… Apart from Yaesu, who knows. Will Yaesu tell you if they plan one… Not a chance, as Ron pointed out, if they did, sales of both rigs would virtually colapse overnight. Lets face it, what radio ham in their right mind could resist paying a three or even four hundred quid premium for the same radio, with a few extra bells and whistle that s/he will never ever use.
If the 817 was a steal at £435, at under £400, it’s a complete no brainer.
Hi Mike,
I have as a back up radio the Yaesu 897D ~~ are they popular? I bought mine new years ago and would never part with it.
Cheers from wet,windy and cold East Sussex.
Mike
as the focus was on FT817 replacement filters not building a new high performance rig.