Graupner MC 16/20 Nautical 41 MHz

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Graupner MC 16/20 Nautical 41 MHz

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7 September 2015 at 09:36 #60189
Quentin Miciak
Participant
@quentinmiciak17245
Purchased this on e-bay and I need to check out the battery and see if it will actually work. it did come with a receiver but no servos. Per the seller, he never actually used it. I am hoping that a local hobby shop may help me out on this part.

If the above works out then the real fun begins!

I need to track down 75 MHz Tx and Rx crystals for the MC 16/20. I noted that on the title of the radio it included "JR".
1. Does anyone know if JR crystals (or any other make) that will fit the MC 16/20?
2. Secondly does anyone know of a supplier (preferably in North America)?
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7 September 2015 at 09:36 #5384
Quentin Miciak
Participant
@quentinmiciak17245
Took a gamble and purchased one – originally from France
7 September 2015 at 10:46 #60190
Dave Milbourn
Participant
@davemilbourn48782
Quentin

Sorry to be the bearer of bad news, but if the set is fitted with a 41MHz RF module then you won't be able to change frequency simply by changing the crystals. The legal frequencies for surface models in the USA are 27/49/50/53/75MHz. i.e. 41MHz is not legal for model operation. The best you can hope for is that a) you don't endanger life, limb or property by operating the set, and b) no-one catches you doing it.

You may be able to find a suitable Tx RF module but you'll definitely need a new receiver. JR made the MC series of radios for Graupner in much the same way as Futaba made the F Series for Robbe. To the best of my knowledge neither are still in production now that Graupner has effectively been turned into a European wholesaler of Chinese and South Korean toys and Robbe has simply gone bust. The two best-known US hobby shops for model boats are probably Loyalhanna Dockyard (NY) and Harbor Models (San Diego).

Dave M
8 September 2015 at 06:22 #60210
Quentin Miciak
Participant
@quentinmiciak17245
Dave

Thanks for confirming that JR was the manufacturer for the Graupner MC 16/20. I'll check out the two hobby stores you mentioned.

The Graupner manual alludes to being able to swap crystals between air and surface frequencies. In fact, the bulk of the manual is focused towards set ups for airplanes and helicopters. However, you mentioned you simply can't swap crystals but that I need Tx and RF modules. The manual makes no mention of modules (or at least I haven't gotten to that part yet).

I understand the crystal part but I'm lost re the module reference. Please explain?

Thanks Quentin
8 September 2015 at 09:03 #60214
Dave Milbourn
Participant
@davemilbourn48782
The photo on Page 11 of the MC16/20 Programming Manual (UK version) shows two different circuit boards – or RF modules – for the Tx, depending on whether you need to use 35MHz or 40MHz. These are the two VHF frequencies permitted for model use in the UK (along with 27MHz). I don't have a copy of the French/European version so I can't say what options are available for the set you have bought. As you say, the bulk of the manual is concerned with programming model aircraft and helicopters, although there is a sizeable section near the back which covers the Nautic switch modules (not the same as the RF modules).

This RF module circuit dictates the frequency at which the signal is transmitted, in combination with the crystal. You can't fit a 35MHz crystal into a 40MHz module and expect it to work properly. In the same way you need a 75MHz module if you want to use 75MHz crystals. Some radios have plug-in modules which fit into a "well" in the back of the Tx case, while others require you to open the Tx case and fit the circuit internally. Similarly some receivers have interchangeable RF modules, but generally they are manufactured for a fixed frequency band and you'd need a 75MHz receiver.

In short, I'm afraid you have a 41MHz radio and you'll need to buy more than just a pair of crystals to change that frequency to 75MHz. Not that you have to take my word for it………………

Dave M
8 September 2015 at 09:39 #60215
Malcolm Frary
Participant
@malcolmfrary95515
The reference to swapping crystals between air and surface probably refers to those countries where the model bands are shared, but odd channels are used by flyers, even by surface. Or the other way round, I don't live there so I don't need to be exact on that. There was a recent report that some UK air band (35MHz) receivers work with 40MHz band crystals, but trying that with a transmitter would be operating the transmitter out of tested specification, voiding any legally required certification.

The RF module in the transmitter has components that operate in the designed band – the crystal fine tunes the frequency that it will transmit at. Put a hugely different crystal in, there is no saying what might happen. There might be RF power transmitted at the crystal frequency, but it might also be transmitted on a few harmonics as well. It might not be at a useful power level, it might be at a higher level than is legal, it might give an impedance mismatch to the output transistors and kill them. The least likely is that it will work properly.

Inside the transmitter case, on high end devices, the part that sends the signal to air is a module that can be changed for another designed for that band, keeping the existing control functions. A fairly popular move recently has been to replace the Radio Frequency module with one operating in the 2.4 GHz band. Obviously, matching 2.4GHz receivers are needed.
8 September 2015 at 17:40 #60223
Dodgy Geezer 1
Participant
@dodgygeezer1
…and it might be quite easy to replace the insides of the Graupner set with those from a 2.4Ghz transmitter (some of which are very cheap), giving you a 2.4ghz system with the more sophisticated controls of the Graupner…
9 September 2015 at 07:46 #60227
Quentin Miciak
Participant
@quentinmiciak17245
Thank You Dave, Malcolm and Dodgy! I learned a lot from you fellows.

When you toss the dice, you sometimes roll a snake eyes. When I stumbled across the Graupner there was only 2 hours left on the auction. I found an online manual but wasn't able to go through it in detail. Nor did I have the knowledge about the crystal / module pairing. My background has been in current RTF and ARTF planes.

I do need to get a 75 MHz radio system since one of my goals is to build some RC model submarines and I actually have two plans for dynamic subs.

Worst case now for me is to convert it to 2.4 GHz for surface ships and air. Best case is to search for JR / Graupner 75MHz modules on sites like e-bay. I actually found JR 75 MHz crystals.

Thanks again fellows!
9 September 2015 at 10:58 #60230
Dave Milbourn
Participant
@davemilbourn48782
Take care when you go looking for anything for this radio. Graupner produced a later version with the suffix HOTT. This is not the same radio as yours and accessories for it (e.g. RF modules) would almost certainly not be compatible with your set. BTW I've had a good Google around and I can't find any reference to who can legally use 41MHz in the USA. Does anyone out there know?

Dave M
9 September 2015 at 11:59 #60234
Banjoman
Participant
@banjoman
Dave,

There's a table available in the Wkipedia article on frequency attribution, here: **LINK**

If I read it correctly, the 41 MHz band is reserved for government use "fixed" and "mobile" whatever that might mean …

/Mattias
9 September 2015 at 13:12 #60235
Banjoman
Participant
@banjoman
The same chart is also available, together with a text version, on the web site of the US National Telecommunications and Information Administration (NTIA): **LINK**.

/Mattias
9 September 2015 at 13:39 #60236
Dave Milbourn
Participant
@davemilbourn48782
As I read it, that table shows the same use for 75MHz as it does for 41MHz, yet 75 is supposedly a dedicated model frequency. It's as clear as mud. I have my doubts that Deputy Sheriff Cletus of Tumbleweed County would know what was in it (or even that it exists) – PC Plod from Brixton certainly wouldn't. Model radio transmitters are limited to a paltry 100mW output anyway, so I know what I'd be tempted to do ……………….

(NB: This opinion does not reflect that of anyone on the staff of Model Boats magazine or Forum – as far as I know!)

DM
9 September 2015 at 14:08 #60237
Dave Milbourn
Participant
@davemilbourn48782
BTW – is it just my imagination or does an upside-down version of John Parker's wiring diagram for Wattle appear above this thread on everyone's screen?
9 September 2015 at 14:19 #60238
Banjoman
Participant
@banjoman
Dave,

You may well be right — that chart is not easy to decipher — but what I read against 75 MHz (74.8 to 75.2 MHz to be precise) is "Aeronautical radionavigation", which is confirmed by the text version (**LINK**), while the spectrum from 40 to 42 MHz just has the label "Fixed Mobile" and, in the chart, the border colour coding that seems to mean "government exclusive".

And yes — an upside-down wiring diagram does indeed appear above this thread; or at least I, too, have observed that phenomenon …

/Mattias
9 September 2015 at 15:15 #60241
Colin Bishop
Moderator
@colinbishop34627
I have removed the diagram!

Colin
9 September 2015 at 15:35 #60244
Dave Milbourn
Participant
@davemilbourn48782
Thanks, Colin.

Mattias
I wonder if anyone uses it.

Dave
9 September 2015 at 17:22 #60245
Colin Bishop
Moderator
@colinbishop34627
I wonder if anyone uses it.

Patriot guidance systems probably…..

Colin
9 September 2015 at 18:38 #60246
Dave Milbourn
Participant
@davemilbourn48782
I think they might be a little more secure than a crude old PWM model signal!

The answer is for Quentin to switch on his Tx and wait for an hour or so. If the Secret Service/FBI/CIA/NSA don't turn up in force at his door and there's no large explosion close by then I reckon he's safe to use it. If they do then it's 'Act Dumb' time. I have a City and Guild Certificate in that….………………..

DM
9 September 2015 at 18:53 #60247
Colin Bishop
Moderator
@colinbishop34627
Well, when a visited HMS Daring a while back all the screens in the ops room appeared to be running Windows XP but I expect you would approve Dave.

Colin
9 September 2015 at 23:21 #60248
Dave Milbourn
Participant
@davemilbourn48782
Yep – Bill's finest creation to date, and if it's good enough for the Royal Navy then it's OK by me. On the original subject, I'd rather have Quentin's old VHF MC16/20 Nautic than any number of current-issue aeroplane/helicopter 2G4 sets. If nothing else they are so UGLY.

DM
10 September 2015 at 07:28 #60249
Quentin Miciak
Participant
@quentinmiciak17245
I didn't expect this much traffic over a couple of questions.

I probably should provide a wee bit more information and context.

First, if Cletus and the rest of the US alphabet show up, I think I'm with in my legal right to use force upon foreign and illegal invaders of this sovereign nation, Canada. Sort of like repelling borders. At minimum, I first would like to build and mount an Estes rocket battery on my springer tug (first build – kit). I'm a Canadian living in Edmonton, Alberta.

Secoundly, the Canadian Frequency Table is a highly complex and detailed. Even though we talk in terms of 75 MHz and 72 MHz over here in Canada, it's actually very specific sub-frequencies that are designated for surface and air RC. Attached is a link to MAAC, which is the hobbiest lobby and link re Federal control of frequencies.

**LINK**

If you really suffer from insomnia, you can take a shot at this link

**LINK**

A couple of detours at this point. I still have no clue what 41 MHz is used for in Canada. I just now that it is not used in the prairies or the arctic (whole separate and fruitless search process). Canada and the USA do coordinate frequencies being that we are aww shucks good buddies and all.

Thirdly, for those who alluded to the "you might use it and see if anyone notices" there is a lot of uninhabited space in this province. I could find spots within a 30 minute drive of my house whereby I could park and there wouldn't be another living soul within 5 miles (8 km.) of me. This of course is purely hypothetical.

The further I drive into certain areas, the larger the radius of no habitation. Well, no one has found any of the bodies yet. Not referring to anything organic.

Cheers! Quentin

PS: I'll post a few pictures of the infernal device that started this thread in a couple of days
10 September 2015 at 08:28 #60251
Banjoman
Participant
@banjoman
Apologies, Quentin, for any part I've played in getting the discussion off on a tangent; as you may have noticed, though, from other threads, this is (for better and for worse) not an unusual occurence on this forum …

Anyway, if I read the official Canadian frequency allocation table correctly, the bandwidth between 40.98 and 41.015 is primarily (upper case letters) for mobile radiocommunications, secondarily (upper and lower case letters) for fixed ditto …

40.98 – 41.015 MOBILE
Fixed
Space Research

… and reserved for space research, which elsewhere in the same document is defined as a "radiocommunication service in which spacecraft or other objects in space are used for scientific or technological research purposes".

In other words, if you soup up the signal suffdiciently on your 41MHz Graupner tx, you just might be able to make a few satellites dance! Or maybe not …

/Mattias

Edited By Banjoman on 10/09/2015 08:28:36

Edited By Banjoman on 10/09/2015 08:29:50
10 September 2015 at 08:28 #60252
Dave Milbourn
Participant
@davemilbourn48782
I didn't realise that you're Canadian. If it's legal in France then surely you could use it in Quebec?

(I'll get me coat, shall I?)

DM
10 September 2015 at 11:24 #60256
Paul T
Participant
@pault84577
Dave

I think you need a bigger spade…….or stop digging this humongous hole.

Fancy not remembering that North America has more than one country and it not that Canada is the size of Andorra.

I will buy you one of these new fangled atlas things to replace your old empire wall chart but until it arrives you can easily identify where Canada is as its that big land mass that sits above the USA and to the left of Greenland, on your chart it says 'here be dragons' and 'Terra incognita'

Paul
10 September 2015 at 11:55 #60258
Dave Milbourn
Participant
@davemilbourn48782
Paul

A lack of specific information on Quentin's part doesn't necessarily equate to a lack of intellect on mine. It's a mistake easily made – except perhaps by someone with your uncanny 20:20 hindsight. Allow me to express my admiration for your high-level technical input to this thread. Now shove off and finish one of those projects you've been tiptoeing around for months.

DM
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