35 mhz - any value

[Martyn K]

Posted by Peter Miller on 07/03/2018 08:17:29:

Correct me if I am wrong but isn't there a problem using 2.4 close to heart pacemakers. Or is that all radios? This being the reason that you have to go outside a hospital to use a mobile phone. or at least into the corridors.

I cant comment on the risk to pacemaker users, but the use of phones in hospitals and aircraft is I believe FUD. I think the real reason is that Airlines and Hospitals simply don't want people having loud conversations on mobile phones in a stressful area.. Remember a phone is transmitting/polling very regularly. Its still an RF/digital signal. Doesn't really make any difference whether someone is actually talking..

[The Wright Stuff]

To be honest, while it is true that the value is simply what people want to pay for it, the second-hand supply enormously exceeds demand, and therefore the value is pretty low.

I think most of the arguments about 35 MHz versus 2.4 GHz are red herrings. Even if both were equally good from a technical perspective, or even if 35 MHz was deemed to be better for whatever reason, the value of 2.4 GHz is still much much higher because that is what the manufacturers are currently producing and supporting and where the high-end features are.

So, to say that "35 MHz sets are almost worthless" does NOT imply that 35 MHz is fundamentally inferior.

[Bob Cotsford]

Posted by Simon P on 07/03/2018 07:24:51:

I would be careful rubbishing the exclusive 35MHz band based on the technology available when it was widely used. We might need it one day, 2.4GHz is a free for all. I wonder if any of the techniques and technologies we have these days on 2.4GHz could be back ported to 35MHz. I know a microchip intended for wireless computer mice is a large part of what gave manufacturers easy access to 2.4GHz and there probably isn’t something like that for 35MHz FM but if a microchip were to exist and have the same ins and outs perhaps it would be possible to transfer new technology to the old 35MHz band.

As I understood it much off the ability of 2.4GHz sets is possible because of the higher frequency/wider bandwidth allowing for higher data transmission speeds. Go back to 35Mhz and you run into transmission rate issues.

[Peter Christy]

Posted by Bob Cotsford on 07/03/2018 11:41:16:

As I understood it much off the ability of 2.4GHz sets is possible because of the higher frequency/wider bandwidth allowing for higher data transmission speeds. Go back to 35Mhz and you run into transmission rate issues.

That's only true if using PCM - and the more "bits" you transmit, the greater the latency! PPM is - for all practical purposes - instantaneous. PCM introduces latency for a number of reasons. First of all, it takes time to encode the signal at the transmitter, secondly, the bandwidth restrictions mean that if you transmit more information, you have to do it more slowly, and finally - the real killer - it has to be decoded at the receiver and checked for validity before being passed on to the servos.

The later generation sets got around some of these problems by using "creative accounting" - only transmitting auxiliary channels every other, or every third or fourth frame. But even on those, there is a perceptible delay between banging the stick over and the servo starting to move. You don't get that with PPM or on 2.4 GHz.

On first generation PCM sets the delay was very noticeable!

But PCM did bring improved security, so it was generally considered an acceptable trade off. And quite honestly, unless you were a stick banging 3D heli pilot, you would probably never notice the difference in practice!

--

Pete

[Alan H]

All my indoor models have the excellent Schultze DSP Rx's in them (used with a Hitec Eclipse Tx) and I have no intention of changing them to 2.4GHz. There's never a frequency clash as everyone else is using 2.4GHz. On the other hand all my outdoor models are on 2.4GHz. As others have said, nobody is interested in buying 35MHz gear.

[J D 8]

More models have whoopsies on landing these days because flyers do not have pennants on their transmitters inicating a change of wind direction.

And they just do not check the windsock.

PS.I also still use 35 on some models.

Edited By J D 8 on 07/03/2018 12:13:45

[Bob Cotsford]

Posted by Peter Christy on 07/03/2018 12:04:56:

Posted by Bob Cotsford on 07/03/2018 11:41:16:

As I understood it much off the ability of 2.4GHz sets is possible because of the higher frequency/wider bandwidth allowing for higher data transmission speeds. Go back to 35Mhz and you run into transmission rate issues.

That's only true if using PCM - and the more "bits" you transmit, the greater the latency! PPM is - for all practical purposes - instantaneous. PCM introduces latency for a number of reasons. First of all, it takes time to encode the signal at the transmitter, secondly, the bandwidth restrictions mean that if you transmit more information, you have to do it more slowly, and finally - the real killer - it has to be decoded at the receiver and checked for validity before being passed on to the servos.

The later generation sets got around some of these problems by using "creative accounting" - only transmitting auxiliary channels every other, or every third or fourth frame. But even on those, there is a perceptible delay between banging the stick over and the servo starting to move. You don't get that with PPM or on 2.4 GHz.

On first generation PCM sets the delay was very noticeable!

But PCM did bring improved security, so it was generally considered an acceptable trade off. And quite honestly, unless you were a stick banging 3D heli pilot, you would probably never notice the difference in practice!

--

Pete

and model match, telemetry, all the bells and whistles that are common on 2.4 sets?

[Peter Christy]

Posted by Bob Cotsford on 07/03/2018 12:24:03:and model match, telemetry, all the bells and whistles that are common on 2.4 sets?

Well, we managed without all those for around 50 years, so whilst they may be nice toys to have, they certainly aren't essential.

Don't get me wrong, I'm not knocking 2.4 GHz. I'm just pointing out that 35 MHz is just as viable as it ever was - maybe even more so now, with most users on 2.4 GHz. And as others have pointed out, if we don't use it, we stand to lose it!

And there's still a lot of people using it in this neck of the woods. The glut of cheap - but good - 35MHz gear also means that those of limited means are still able to enjoy the hobby - perhaps with better gear than they would have managed in the past!

--

Pete

[eflightray]

When you're flying and some annoying person comes up and starts asking the usual silly questions, and just being a distraction, you can't swing round and clobber them with the aerial with 2.4. (without it looking deliberate  .

35MHz did have some useful advantages.

Ray.

[rcaddict]

so the moral of the story is by keeping my 35 gear lying in a box somewhere in my garage Im doing us model fraternity a great service

[Cuban8]

I never had a problem with PPM 35 meg gear itself for all the years I'd been flying, but the fundamental weakness with all those old radios was the not insignificant risk of getting shot down by a club mate or rogue operator in the next field. I'd not want to go back to all the faffing about with peg boards and people fitting the wrong crystals and aerial flags. How so easily we forget all that stuff.

[Bob Cotsford]

I never had a problem with drum brakes, carbs and points ignition either. Set your points every 500 miles and off you go. Having experienced disc brakes, fuel injection, ABS and all the rest - would I go back to the old ways by choice? Not a chance. It's the same with 2.4, I enjoy having 16 channels available, S-Bus, signal strength and battery voltage warnings, model match and all the rest that comes with it. I still have an FF8 and FF9 that I could convert back to 35 if need be, I just hope I never need to.

Up until a couple of years ago we had something like half of the club running 35, now I think everyone's on 2.4. I bet we have a fair bit of 35Mhz gear tucked away between us.

Ray, you have a good point re the long aerials, they did have their uses.

[Cuban8]

I'm confident in saying that both of my clubs are exclusively 2.4 now.

[Peter Christy]

Posted by Bob Cotsford on 07/03/2018 16:03:21:

I never had a problem with drum brakes, carbs and points ignition either. Set your points every 500 miles and off you go. Having experienced disc brakes, fuel injection, ABS and all the rest - would I go back to the old ways by choice? Not a chance.

Back in 2012, I drove over to Ballenstedt in the old East Germany (near the Polish border) in my (then) 41 year old car. Going around Hanover, there was a massive traffic jam on the ring road, and it was a boiling hot summer's day! To cool the engine, I popped the bonnet onto the latch (it opens forward, so no safety issues), and all the Germans alongside were helpfully pointing out that my bonnet was open!

The car got through the jam without missing a beat, and having shut the bonnet proceeded down the autobahn quite happily. However, for the next ten miles or so, I passed a stream of new Audis, BMWs, Mercs and VWs, all at the roadside with steam pouring out the front. I helpfully pointed out that their bonnets were open, but its true - they have no sense of humour!

I was really thankful I was in an old, but very simple car! If anything HAD gone wrong, it would have been easy to fix at the roadside!

And yes, I quite agree that modern 2.4 GHz radio gear is cheap and reliable. But it is also largely soul-less. Perhaps why there is such a movement building for "retro" models, with single channel leading the way!

I have to say that of late, I've been getting as much fun out of flying a single channel model - complete with rubber band driven escapement - than I have out of any of my newer and fancier toys!

--

Pete

[ken anderson.]

Posted by Paul Marsh on 06/03/2018 18:00:35:

35 Meg is dead, and all my 550 aircraft are all on 2.4, but spread over the makes of Futaba, Spektrum, Hitec and Tactic. None on 35. Have kept one or two JR rx's for my X-347, for sentimental sake, thats all..

..................................................................................

Paul-you have to be a contender for the Guinness book of records with all of the model aircraft (550)you have..

ken Anderson ne...1 records dept.

[Cuban8]

I had 35 gear from 1984 to 2012 (ppm) and 27 before that, and I can honestly say that I don't recall ever experiencing a glitch that was noticeable whilst flying the model. With 35 PCM I've seen several flyer's models lock out for no good reason and a couple of nice models crashed after the radio froze. I could never understand the craze for expensive PCM sets that seemed no better than PPM.

[Paul Marsh]

The main reason why 35Mhz is not used, is that all the shows allow 2.4 only, due to amount of disciplines used. In the past, trying to control the peg board at Weston Park flying in the night was horrendous!

I turned up and put my peg on 78 and turned on. A model crashed and was destroyed. A very irate pilot said who switched on ch 78. I said me, but my peg was on the board. his key was on the floor. What happened, is the peg board was knocked over and someone put the keys back - in different places!

I had shot someone down, even not my fault. The poor guy whos plane had gone in understood, although at first before he found out, wanted me to pay for his plane.

After that, when 2.4 came out, i never used 35 meg again and never will. I found it dangerous - being shot down on at least 3 occasions, one where someone turned up and turned on, and my Gangster Mk1 went in...

It may work, now, but some things are better left in the past...

[Former Member]

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[Former Member]

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[Former Member]

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[ken anderson.]

3 cheers for Hedy lamarr....and pretty with it...clever lass.
Ken Anderson...ne...1...2.4 dept

[rcaddict]

peg boards .......forgot about them - what a pain

[Former Member]

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[Tom Thomas]

The old view that using mobiles in hospitals would interfere with life saving equipment is just that, ....old.... my wife watches a well known doc on londons St. George's etc... and almost every episode shows people on phones.

So no peter, no need to move away from the patient.

[Dave Cunnington]

Oldgit : If after all that has been said here you are still wanting rid, and you are not too far from Lincolnshire, then please let me know

Rgds DC