Europa-List Digest Archive

Mon 01/20/14


Total Messages Posted: 14



Today's Message Index:
----------------------
 
     1. 01:31 AM - Re: Dipole aerial (Grahamhall123@gmail.com)
     2. 05:31 AM - Re: Re: Ammeters & Voltmeters (Greg Fuchs)
     3. 05:54 AM - Re: Ammeters & Voltmeters (Greg Fuchs)
     4. 06:33 AM - Re: Ammeters & Voltmeters (Max Cointe (Free))
     5. 06:42 AM - aluminium sheet supplier in uk? (Rowland Carson)
     6. 06:53 AM - Re: Ammeters & Voltmeters (Rowland Carson)
     7. 07:12 AM - Re: aluminium sheet supplier in uk? (John Price)
     8. 08:28 AM - Re: Re: Ducati rectifier/regulators (Jan de Jong)
     9. 08:33 AM - Re: Ammeters & Voltmeters (Max Cointe (Free))
    10. 08:47 AM - Re: aluminium sheet supplier in uk? (tennant)
    11. 10:03 AM - Re: aluminium sheet supplier in uk? (PETER MORGANS)
    12. 11:39 AM - Re: Re: aluminium sheet supplier in uk? (Rowland Carson)
    13. 01:03 PM - Re: Re: Ammeters & Voltmeters (Fred Klein)
    14. 02:22 PM - Re: Re: Ducati rectifier/regulators (Greg Fuchs)
 
 
 


Message 1


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    Time: 01:31:29 AM PST US
    Subject: Re: Dipole aerial
    From: "Grahamhall123@gmail.com" <grahamhall123@gmail.com>
    Hi Dave, Thanks for most helpful reply. When time and weather allow I will give a go! Will let you know how it goes. Regards Graham. On Jan 19, 2014, at 6:43 PM, "David DeFord" <deford.dave@gmail.com> wrote: > > Graham, > > You are right to be dubious about your results, as they don't reflect the > behavior of an undisturbed dipole antenna. Readings like these are most > often caused by current flowing on the outside of the shield of the coax > feed line. This is why we put toroid cores around the coax near the feed > point of the antenna. If the size and material of the core are > satisfactory, the outside current is blocked. What you read in this case > reflects the characteristics of the antenna by itself, rather than the > antenna plus the feed line, which acts like another antenna connected in > parallel with the dipole. > > The easiest way to determine whether your toroid core is effective is to > simply grab the coax in your hand near the end that connects to the radio > (where the swr meter should also be located), while watching the meter > indication. Your should be able to run your hand along the coax over a > length of about a meter with minimal disturbance in the swr meter reading. > Alternatively, changing the length of the feed line by about half a meter > should have little effect on the reading. If this is not the case, you need > a more effective toroid. Ferrite cores are generally better than powdered > iron, and larger cores are more effective than smaller cores, assuming the > same inner diameter and core material. You should also try not to disturb > the antenna with metal objects and human bodies within 3 meters or so. > > Good luck! > > Dave DeFord > N135TD > >> -----Original Message----- >> >> --> <grahamhall123@gmail.com> >> >> Can anyone help please. >> I am trying to tune my dipole aerial as per instructions from Europa to >> my krt-2 radio using a swm. >> My initial reading were >> Swm 1.7 on 118.00 frequency >> 5 on 127.00 >> 2.6 on 136.9 >> >> I therefore started trimming 3 mm at a time off the ends of each copper >> tape. >> This caused the lowest frequency swm reading to increase, the middle >> range to fall and the 136.9 also to fall. >> The results for each 3mm trim were >> 118.00. 127.00. 136.9 >> >> 1.4 5. 2.4 >> >> 1.6. 4.2. 2.0 >> >> 2. 4.0. 1.9 >> >> >> 2.4. 3.0. 1.6 >> >> >> 3.0. 2.6. 1.4 >> >> >> At this stage I lost my nerve and stopped trimming the aerial! >> >> Europa instructions say middle range frequency should be lowest swm >> reading. >> >> Can any of you out there advise on what I've done or indeed should do? >> >> Best wishes to you all. >> >> >> Graham. > > > > >


    Message 2


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    Time: 05:31:46 AM PST US
    From: "Greg Fuchs " <gregoryf.flyboy@comcast.net>
    Subject: Re: Ammeters & Voltmeters
    Maybe there is a way to make the Ducatti regulator much more reliable. Going by the schematic on the Contrails website, there is nothing much special about this regulator. It is very similar to many other motorcycle regulators that operate without a field control voltage. At least it is similar to a regulator I made for my own motorcycle, about 5 years ago. Similar to what someone explained a few emails ago: The unit monitors the regulated DC output voltage. If it is too high, it grounds the alternating current (AC) that is coming direct off the alternator, until the DC output voltage is in range (probably something less than about 15 volts). If the load of the aircraft is high, the alternator voltage (AC) is low hence the DC output is less than 15V and the clamping device need not fire. Hence, the clamping device (SCR, or the like) will LAST LONGER with higher aircraft loads. Then why are people seeing the regulator failing at high loads? Well, it must be the rectifier diodes that are failing. They are the only high-power devices that COULD fail, based on the schematic (which isn't drawn perfectly, but good enough to tell what's happening). Luckily, both sides of the diodes in the regulator are accessible by the external terminals of the regulator itself. If one were to take two high-current diodes (maybe use Schottkey's, which have a much smaller turn-on voltage..that will almost guarantee complete bypass of the smaller Ducatti diodes), with their cathodes connected to the 'R' terminal and each one of the anodes connected to the 'G' terminal on the regulator (one for each), the internal diodes would either be helped or mostly bypassed, as long as the turn-on voltage for the power diodes was less than or equal to the turn-on voltage for the Ducatti's internal diodes. Doesn't hurt to try it either way.. Alternatively, one could connect the anode of one diode (lets call it diode #1) to one of the 'G' terminals (on the Regulator) and the cathode to the 'R', while diode #2 anode would be connected to the other 'G', with its cathode connected to the 'B+' terminal on the Regulator. This should be do-able, since B+ and R are one and the same, according to the schematic. Has anyone done this?....or maybe someone can try and report back any success. That's the way I see it anyway, Greg


    Message 3


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    Time: 05:54:29 AM PST US
    From: "Greg Fuchs " <gregoryf.flyboy@comcast.net>
    Subject: Ammeters & Voltmeters
    Fred, By definition, a current is measured by sticking a voltmeter across a series resistor...albeit a very very small-valued one, so as not to impede the current flow in the circuit. It is small enough to be thought of as a wire. Similar to what Graham was saying, I too, have used the voltage drop across a wire to measure current. However, a ready-made shunt is preferable. It is designed to be more stable (linearized) than a wire (over heating effects, etc). A store-bought current meter usually has a calibrated shunt already installed between the two terminals in the back of the meter. Large wires need to run to this type. Alternatively, the 'Resistor' could be located remotely i.e.. by the battery. This way large wires do not need to be run to the instrument on the panel. It can be complicated for sure. Might be easier to just run the heavy wires to the pre-made Current meter and call it good. My explanations act like they've had a six-pack sometimes. Hope this makes sense. Greg -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Fred Klein Sent: Sunday, January 19, 2014 8:20 AM Subject: Re: Europa-List: Ammeters & Voltmeters Frans...thank you for your thoughtful reply to my concerns, especially by spelling things out in crayon to a guy who is electronically-challenged...just what I needed, although, when you write: > To measure amps, you need to have a resistor somewhere in the wire. I > prefer to have this directly at the battery because this resistor is > doing the least harm at that place, and if it fails, has the least > impact on your flight. And it gives you the most useful information at > that location. ...I must admit that I have no idea WHY a resistor is essential, nor can I imagine what criteria are appropriate for sizing such a resistor, nor do I understand why failure would cause minimal harm if it's located directly at the battery... All the best, Fred


    Message 4


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    Time: 06:33:24 AM PST US
    From: "Max Cointe (Free)" <mcointe@free.fr>
    Subject: Ammeters & Voltmeters
    Hi there All, Excuse my french, but wouldn't be necessary that the current sunk by the starter doesn't go through the shunt? Max Cointe mcointe@free.fr F-PMLH Europa XS_TriGear Kit #560-2003 912ULS/AirmasterAP332 490 hours F-PLDJ DynAro MCR 4S Kit #27-2002 912ULSFR/MTProp MTV7A 1600 heures -----Message d'origine----- De: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] De la part de Greg Fuchs Envoy: lundi 20 janvier 2014 14:54 : europa-list@matronics.com Objet: RE: Europa-List: Ammeters & Voltmeters --> <gregoryf.flyboy@comcast.net> Fred, By definition, a current is measured by sticking a voltmeter across a series resistor...albeit a very very small-valued one, so as not to impede the current flow in the circuit. It is small enough to be thought of as a wire. Similar to what Graham was saying, I too, have used the voltage drop across a wire to measure current. However, a ready-made shunt is preferable. It is designed to be more stable (linearized) than a wire (over heating effects, etc). A store-bought current meter usually has a calibrated shunt already installed between the two terminals in the back of the meter. Large wires need to run to this type. Alternatively, the 'Resistor' could be located remotely i.e.. by the battery. This way large wires do not need to be run to the instrument on the panel. It can be complicated for sure. Might be easier to just run the heavy wires to the pre-made Current meter and call it good. My explanations act like they've had a six-pack sometimes. Hope this makes sense. Greg -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Fred Klein Sent: Sunday, January 19, 2014 8:20 AM Subject: Re: Europa-List: Ammeters & Voltmeters Frans...thank you for your thoughtful reply to my concerns, especially by spelling things out in crayon to a guy who is electronically-challenged...just what I needed, although, when you write: > To measure amps, you need to have a resistor somewhere in the wire. I > prefer to have this directly at the battery because this resistor is > doing the least harm at that place, and if it fails, has the least > impact on your flight. And it gives you the most useful information at > that location. ...I must admit that I have no idea WHY a resistor is essential, nor can I imagine what criteria are appropriate for sizing such a resistor, nor do I understand why failure would cause minimal harm if it's located directly at the battery... All the best, Fred


    Message 5


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    Time: 06:42:28 AM PST US
    From: Rowland Carson <rowlandcarson@gmail.com>
    Subject: aluminium sheet supplier in uk?
    I'm seeking a source of small quantities of aluminium sheet in UK - eg 6061 or 6082. This is mainly to modify the standard ducting to fit Neville's cowl, but there are also other small parts I want to fabricate. There used to be an outfit called PFA Metals but they seem to have folded their tent. I can't find another firm that does 6061 or 6082 in small quantities (although there are several who offer aluminium of anonymous grades). Does anyone know of such a firm in UK? in friendship Rowland | Rowland Carson ... that's Rowland with a 'w' ... | <rowlandcarson@gmail.com> http://www.rowlandcarson.org.uk | Skype, Twitter: rowland_carson Facebook: Rowland Carson | pictures: http://picasaweb.google.com/rowlandcarson


    Message 6


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    Time: 06:53:01 AM PST US
    From: Rowland Carson <rowlandcarson@gmail.com>
    Subject: Re: Ammeters & Voltmeters
    On 20 Jan 2014, at 14:32, Max Cointe (Free) wrote: > Excuse my french, but wouldn't be necessary that the current sunk by the > starter doesn't go through the shunt? Max - the shunt is positioned beyond take-off point for the starter motor. See the attached wiring diagram for my Europa G-RODO, based on the one in the manual. in friendship Rowland | Rowland Carson ... that's Rowland with a 'w' ... | <rowlandcarson@gmail.com> http://www.rowlandcarson.org.uk | Skype, Twitter: rowland_carson Facebook: Rowland Carson | pictures: http://picasaweb.google.com/rowlandcarson


    Message 7


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    Time: 07:12:53 AM PST US
    Subject: Re: aluminium sheet supplier in uk?
    From: "John Price" <nicolaandjohn@talktalk.net>
    Try LAS Aerospace in Devon or I've sourced aluminium from 'Click Metal'. They will cut pretty much to any size. John. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=417269#417269


    Message 8


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    Time: 08:28:59 AM PST US
    From: Jan de Jong <jan_de_jong@casema.nl>
    Subject: Re: Ducati rectifier/regulators
    Re two-phase bridge rectifier/regulator. The 2 thyristors in the rectifier bridge do not short the AC input or "dump" anything. On the contrary, they disconnect the DC output from the AC input when the output voltage threatens to exceed the set voltage. All output current passes through one branch of one diode and one thyristor in series half the time and through the other identical branch also half the time. Heat development is proportional to the output current and the voltage drop across a branch. Voltage drops increase somewhat with current, so heat development increases more than linearly with output current. In the Ducati device the diode is reportedly a MR2510 pill (typically 0.75V at 10A, 0.8V at 20A), the thyristor can be a 2N6504 (typically 1.1V at 10A, 1.3V at 20A). So at 10A the two branches of the bridge are each expected to generate 0.5 x (7.5 + 11) = 9.25W (total 18.5W) of heat. And at 20A the two branches of the bridge are each expected to generate 0.5 x (16 + 26) = 21W (total 42W) of heat. ( a failure mode for the Ducati device is reportedly the loss of continuity of a diode pill attachment through thermal cycling; fitting external parallel diodes has been proposed as a solution; replacing the whole device seems more sensible ) Cheers, Jan de Jong


    Message 9


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    Time: 08:33:50 AM PST US
    From: "Max Cointe (Free)" <mcointe@free.fr>
    Subject: Ammeters & Voltmeters
    Many thanks Rowland! Very helpfull. Max Cointe mcointe@free.fr F-PMLH Europa XS_TriGear Kit #560-2003 912ULS/AirmasterAP332 490 hours F-PLDJ DynAro MCR 4S Kit #27-2002 912ULSFR/MTProp MTV7A 1600 heures -----Message d'origine----- De: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] De la part de Rowland Carson Envoy: lundi 20 janvier 2014 15:52 : europa-list@matronics.com Objet: Re: Europa-List: Ammeters & Voltmeters On 20 Jan 2014, at 14:32, Max Cointe (Free) wrote: > Excuse my french, but wouldn't be necessary that the current sunk by > the starter doesn't go through the shunt? Max - the shunt is positioned beyond take-off point for the starter motor. See the attached wiring diagram for my Europa G-RODO, based on the one in the manual. in friendship Rowland | Rowland Carson ... that's Rowland with a 'w' ... | <rowlandcarson@gmail.com> http://www.rowlandcarson.org.uk | Skype, Twitter: rowland_carson Facebook: Rowland Carson | pictures: http://picasaweb.google.com/rowlandcarson


    Message 10


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    Time: 08:47:44 AM PST US
    Subject: Re: aluminium sheet supplier in uk?
    From: "tennant" <barrington.tennant@gmail.com>
    Hi Rowland, I have 25 sheets of 6061 T6 - 1mm x 1220 x 1830 mm in stock from an over delivery. How much do you want?? I could cut up a sheet to packet service size & send it pretty cheaply. Barry post at tennant-metall.de -------- Barry Tennant D-EHBT At EDLM - Germany Read this topic online here: http://forums.matronics.com/viewtopic.php?p=417288#417288


    Message 11


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    Time: 10:03:29 AM PST US
    From: PETER MORGANS <petermorgans181@btinternet.com>
    Subject: Re: aluminium sheet supplier in uk?
    Hi Rowland,=0AYou might try Skycraft at this link --------- http://www.sky- craft.co.uk/acatalog/Skycraft_Home_Builder_Permit_Aircraft_Aluminium_Stock_ Material_6061-T6_Sheet.html=0A=0ARegards=0APeter Morgans=0A =0A=0A_________ _______________________=0A From: Rowland Carson <rowlandcarson@gmail.com> =0ATo: Europa e-mail list list <europa-list@matronics.com> =0ASent: Monday, 20 January 2014, 14:41=0ASubject: Europa-List: aluminium sheet supplier in rson@gmail.com>=0A=0AI'm seeking a source of small quantities of aluminium sheet in UK - eg 6061 or 6082. This is mainly to modify the standard ductin g to fit Neville's cowl, but there are also other small parts I want to fab ricate.=0A=0AThere used to be an outfit called PFA Metals but they seem to have folded their tent. I can't find another firm that does 6061 or 6082 in small quantities (although there are several who offer aluminium of anonym ous grades). Does anyone know of such a firm in UK?=0A=0Ain friendship=0A =0ARowland=0A=0A| Rowland Carson- - - - - ... that's Rowland with a 'w' ...=0A| <rowlandcarson@gmail.com>- - - - - - http://www. rowlandcarson.org.uk/=0A| Skype, Twitter: rowland_carson- - - Faceboo k: Rowland Carson=0A| pictures: http://picasaweb.google.com/rowlandcarson ==================


    Message 12


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    Time: 11:39:19 AM PST US
    Subject: Re: aluminium sheet supplier in uk?
    From: Rowland Carson <rowlandcarson@gmail.com>
    On 20 Jan 2014, at 16:47, tennant wrote: > I have 25 sheets of 6061 T6 - 1mm x 1220 x 1830 mm in stock from an over delivery. > > How much do you want?? > > I could cut up a sheet to packet service size & send it pretty cheaply. Barry - 25 sheets of 6ft x 4ft - that sounds like a serious over-delivery! I'd like to have some pieces about 18 inches long by a foot wide. Could you guillotine a quarter (ie 457.5mm) off the length of one of your sheets then cut that 3 times crosswise to give 4 pieces each 457.5mm x 305mm? Would that go through the post OK? I'm posting this reply on the forum to also thank all those who responded, but I suggest that Barry & I continue our negotiations in private from here on ... For comparison, I checked on the price and availability from the suppliers suggested by other posters and found thus: for 48" x 24" x 0.040" 6061 T6 Skycraft 30.66; delivery 11.00; VAT 8.33; total 49.99 LAS 48.08; delivery 12.50; VAT 11.72; total 70.30 Click Metal only 1050 grade (pure aluminium, too soft) available in 1mm thick - they do 6000-series grades in other things such as profiles or thicker plate. Thanks again to everyone for their suggestions. in friendship Rowland | Rowland Carson ... that's Rowland with a 'w' ... | <rowlandcarson@gmail.com> http://www.rowlandcarson.org.uk | Skype, Twitter: rowland_carson Facebook: Rowland Carson | pictures: http://picasaweb.google.com/rowlandcarson


    Message 13


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    Time: 01:03:34 PM PST US
    Subject: Re: Ammeters & Voltmeters
    From: Fred Klein <fklein@orcasonline.com>
    Jim...thanks for your help...I did not realize I needed to order an external shunt w/ the little modular Mitchel ammeter...all will be well...Fred


    Message 14


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    Time: 02:22:05 PM PST US
    From: "Greg Fuchs " <gregoryf.flyboy@comcast.net>
    Subject: Re: Ducati rectifier/regulators
    Respectfully, I believe that the circuit configuration that you are thinking of is incorrect, Jan de Jong. The SCR's do EXACTLY 'dump' the AC output DIRECTLY to ground. When one end of the thyristor connects to the alternating current output of the coil, and the other end to ground...then that is all they can do but short the AC output to ground. It is not acting as a PWM-like device at all, simply a grounding device. Call it a direct-connect. You mention heat. The direct-connect method is the best way to deal with the heat. The forward voltage drop of the 'dumping' device is low, and the current does not need to go through the diodes at all, which are bypassed...hence your lowest heat output. Since the 'dumping device' connects the alternator output directly to ground, without going through the diode, what is the power dissipated? While in the dumping mode, lets say the current to dump was 10 amps(I'll use your generously supplied information, so I don't have to look up specs) it would be 1.1V * 10 amps. That's it. 11 watts. That is much better than the 18 Watts in your configuration. >( >a failure mode for the Ducati device is reportedly the loss of continuity of a diode pill attachment through thermal >cycling; fitting external parallel diodes has been proposed as a solution; replacing the whole device seems more >sensible >) Well, maybe so! However, if the failure mode is a loss in continuity, that would mean the diodes are opening. That would also mean that connecting the external diodes to the regulator would bring it back to life! Regards, Greg -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Jan de Jong Sent: Monday, January 20, 2014 7:40 AM Subject: Re: Europa-List: Re: Ducati rectifier/regulators Re two-phase bridge rectifier/regulator. The 2 thyristors in the rectifier bridge do not short the AC input or "dump" anything. On the contrary, they disconnect the DC output from the AC input when the output voltage threatens to exceed the set voltage. All output current passes through one branch of one diode and one thyristor in series half the time and through the other identical branch also half the time. Heat development is proportional to the output current and the voltage drop across a branch. Voltage drops increase somewhat with current, so heat development increases more than linearly with output current. In the Ducati device the diode is reportedly a MR2510 pill (typically 0.75V at 10A, 0.8V at 20A), the thyristor can be a 2N6504 (typically 1.1V at 10A, 1.3V at 20A). So at 10A the two branches of the bridge are each expected to generate 0.5 x (7.5 + 11) = 9.25W (total 18.5W) of heat. And at 20A the two branches of the bridge are each expected to generate 0.5 x (16 + 26) = 21W (total 42W) of heat. ( a failure mode for the Ducati device is reportedly the loss of continuity of a diode pill attachment through thermal cycling; fitting external parallel diodes has been proposed as a solution; replacing the whole device seems more sensible ) Cheers, Jan de Jong




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