Today's Message Index:
----------------------
1. 08:36 AM - Spinner CJ-6 (Robin Hou)
2. 08:49 AM - Re: Spinner CJ-6 (Gary Gabbard)
3. 12:24 PM - Re: Spinner CJ-6 (Cpayne)
4. 01:09 PM - Re: Antenna Yak52 (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
5. 08:38 PM - Re: Antenna Yak52 (Walter Lannon)
6. 08:49 PM - Re: Antenna Yak52 (Walter Lannon)
Message 1
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What kind of spinner is on this CJ?
http://www.abpic.co.uk/popup.php?q=1350846
It looks like those Reno round engine racer; very slick!
Is there any speed advantage? Do you remove the gill shutter?
Message 2
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| Subject: | Re: Spinner CJ-6 |
Don't remove the Gills. In winter operation
you will nor be able to keep to the oil warm enough
to maintain oil pressure. If you don't believe
that try Flying around on a cold winter day
with the Gills wide open. It won't take very long
before your oil pressure will drop below minimum
red line. Gary. CJ N22YK
Sent from my iPhone
On Jul 7, 2012, at 8:32, Robin Hou <rmhou@yahoo.com> wrote:
> What kind of spinner is on this CJ?
> http://www.abpic.co.uk/popup.php?q=1350846
>
> It looks like those Reno round engine racer; very slick!
>
> Is there any speed advantage? Do you remove the gill shutter?
>
>
>
>
Message 3
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| Subject: | Re: Spinner CJ-6 |
That would be my airplane a few years ago, it now has different LERX and I replaced
that Les Crowder spinner with a smaller one. The reason is that you cannot
mount the shutters with this spinner. Works OK down here in Florida but not
way up North in Waycross, GA during the winter.
BTW, selling that spinner this week, look for it in bright Red on another CJ. Yes
it did add a few knots...but only after everything else is OK, rigging, etc.
Craig Payne
Message 4
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Roger that Warren. As you know, the feedpoint impedance of a 1/4 wave radiator
is actually about 36 ohms, giving a best match of about 1.5 to 1 VSWR. Whereas
in order to feed a 5/8 wave design, you try to make the 5/8 wave antenna appear
to be about 3/4 wavelength which will establish a pretty good match and also
give the ideal low angle of radiation that can be gained with the actual 5/8
wave length of the antenna. This is typically done by using a base loading
coil. Typical aircraft designs avoid 5/8 wavelength due to the compressed pattern
that is good for fixed stations, but bad for a moving platform with pitch
and roll.
Only really cheap avionics shops use RG-58 for the reasons you specified. A much
better alternative and what aircraft owners should specifically ask for is RG-142
B/U which is a teflon dielectric silver tinned double shielded coax that
has a higher velocity factor than standard coax and thus lower loss. This coax
is good for short runs even at 1.5 GHz, such as a GPS antenna for example.
If more flexibility is needed in the coax (the teflon is kind of stiff), I recommend
RG-223, which is the same as RG-142, except it has a poly dielectric rather
than teflon.
If you are a warbird with LONG coax runs, I recommend RG-393/U which is the roughly
0.5" variety of PTFE dielectric coax. It has even lower loss (large center
conductor) is also silver tinned. Again if stiffness is a factor, the alternative
is RG-214.
I recommend avoiding crimp on connectors of ANY type. Avionics shops love them
because they are easy and FAST to put on. Putting a standard BNC or TNC connector
takes time, and a little bit of soldering skill. That said, I never ever
use crimp-on's.
But just for giggles let's compare ....... A 20 foot run of RG-142 at 130 Mhz
will give a loss of about 0.9 dB But with tongue in cheek, let me also submit
that a 20 foot run of RG-58 will have a loss of 1.0 dB, thus a difference
of only 0.1 dB. At 1500 Mhz, basically GPS range, you are looking at a 20 foot
run of RG-58 having 3.8 dB of loss and RG-142 3.2 dB, a difference of 0.6
dB
So a true nit-picker would submit that the higher cost of RG-142 is not worth it
..... but I submit it is much more rugged, and will last MUCH LONGER compared
to anything else.
Of course, the real advantage of RG-393 is that it will handle 10 Kw of average
power at 20 Mhz... needed when you are running a 3CX3000A7 with 7000 volts on
the plate.
Take care Warren,
Mark
WA3JPY
________________________________
From: owner-yak-list-server@matronics.com on behalf of Warren Hill
Sent: Fri 7/6/2012 2:47 PM
Subject: Re: Yak-List: Antenna Yak52
Mark,
As you know, a straight 1/4 wavelength vertical radiator has a relatively narrow
bandwidth. The SWR will be good at 1/4 and possibly 5/8 wavelength, but rises
quickly after that. There is no way to make a single element vertical antenna
efficient from 118 to 136 MHz. It can be tuned at the center frequency and we
just have to accept the high SWR towards the ends of the band. Also, the anodized
aluminum panels on the CJ do not always conduct well between each one.
The other weak point in aviation communications is the coax and the BNC connectors.
RG-58 is pretty lossy at 120 MHz and a poorly fashioned BNC connector easily
has a 1 to 2 dB insertion loss. For every 3 dB of loss the signal strength
is cut by 50%, outgoing and incoming. So... a non-resonant antenna with a shaky
counterpoise, two low quality, crimped BNC connectors on RG-58 coax and even
the best radio may seem less than adequate from 20 miles out.
The good news is that just about everything we do is line of sight and at these
frequencies it doesn't take much radiated power to maintain a reasonable signal
strength.
Warren
On Jul 6, 2012, at 11:17 AM, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
wrote:
>
> I might point out that physics is a problem here as well.
>
> One piece of metal as an antenna cannot be made to provide a
> characteristic impedance of 50 ohms from 118 to 136 MHz. You pretty
> much have to come up a way around that issue. :-)
>
> Mark
>
> p.s. Go ahead Brian.
>
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Hans Oortman
> Sent: Friday, July 06, 2012 4:23 AM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Antenna Yak52
>
>
> Thanks Mark....I can not reach the guts of the antenna myself but found
> a
> small guy who can.... Jan probably has still an antenna, so I'll wait
> what
> he can find.
>
> Buy the way: I hate matching networks, the only thing it does is match
> the
> impedance but pulls down the efficiency....
>
> I'll keep you posted!
>
> Hans
>
>
> Op 05-07-12 00:42, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
> <mark.bitterlich@navy.mil> schreef:
>
> Point,
>> MALS-14 64E" <mark.bitterlich@navy.mil>
>>
>> The stock Russian antenna has a small matching network inside. If you
> want to
>> go to the effort, the radiator can be replaced. It is actually a
> threaded
>> tapered rod. The best bet would be to ask around and see if you can
> find an
>> old one that someone removed that you can just thread in and be done.
>>
>> Personally, I took the antenna off, then drilled the original plate
> for a more
>> modern antenna and mounted it on the same plate. Doing it this way
> you really
>> should not notice any damage to your paint? In any case, you would
> have to
>> slice around the mounting plate so you could remove it. I think I
> have one
>> that I could take pictures of for you, but it would take a few days
> since I am
>> currently not home. If anyone else has pictures, I am sure that would
> help
>> you much better than this email.
>>
>> Mark
>>
>>
>> ________________________________
>>
>> From: owner-yak-list-server@matronics.com on behalf of Hans Oortman
>> Sent: Wed 7/4/2012 5:11 PM
>> To: yak-list
>> Subject: Yak-List: Antenna Yak52
>>
>>
>> Guys,
>>
>> Has anybody removed or swapped the antenna on a Yak52??
>> Mine is broken and completely corroded so needs to be replaced.
>> If I want to remove it, it means damaging the paint and I was
> wondering if
>> only the radiator could be removed rather than the whole assembly??
>> Pictures or drawings would be appreciated!
>>
>> Thanks!
>>
>> Hans O.
>> RA3326K
>> Netherlands
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
Message 5
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| Subject: | Re: Antenna Yak52 |
Hi Mark;
Just finishing up the avionics installations in my CJ project. I used Mil.
Spec. M17/128-RG400 for all units. 2 comms, TXPDR and GPS. Had
intended to use RG 142 for the GPS but the local avionics shop (who have a
very good reputation) said the RG400 would be fine. It's only a 3 ft. run
so I assume either would be OK. Both are silver plated central conductor
and double silver plated shields.
Do you see any problem with that?
Many thanks;
Walt
-----Original Message-----
From: Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
Sent: Saturday, July 07, 2012 1:07 PM
Subject: RE: Yak-List: Antenna Yak52
MALS-14 64E" <mark.bitterlich@navy.mil>
Roger that Warren. As you know, the feedpoint impedance of a 1/4 wave
radiator is actually about 36 ohms, giving a best match of about 1.5 to 1
VSWR. Whereas in order to feed a 5/8 wave design, you try to make the 5/8
wave antenna appear to be about 3/4 wavelength which will establish a pretty
good match and also give the ideal low angle of radiation that can be gained
with the actual 5/8 wave length of the antenna. This is typically done by
using a base loading coil. Typical aircraft designs avoid 5/8 wavelength
due to the compressed pattern that is good for fixed stations, but bad for a
moving platform with pitch and roll.
Only really cheap avionics shops use RG-58 for the reasons you specified. A
much better alternative and what aircraft owners should specifically ask for
is RG-142 B/U which is a teflon dielectric silver tinned double shielded
coax that has a higher velocity factor than standard coax and thus lower
loss. This coax is good for short runs even at 1.5 GHz, such as a GPS
antenna for example. If more flexibility is needed in the coax (the teflon
is kind of stiff), I recommend RG-223, which is the same as RG-142, except
it has a poly dielectric rather than teflon.
If you are a warbird with LONG coax runs, I recommend RG-393/U which is the
roughly 0.5" variety of PTFE dielectric coax. It has even lower loss (large
center conductor) is also silver tinned. Again if stiffness is a factor,
the alternative is RG-214.
I recommend avoiding crimp on connectors of ANY type. Avionics shops love
them because they are easy and FAST to put on. Putting a standard BNC or
TNC connector takes time, and a little bit of soldering skill. That said, I
never ever use crimp-on's.
But just for giggles let's compare ....... A 20 foot run of RG-142 at 130
Mhz will give a loss of about 0.9 dB But with tongue in cheek, let me
also submit that a 20 foot run of RG-58 will have a loss of 1.0 dB, thus a
difference of only 0.1 dB. At 1500 Mhz, basically GPS range, you are
looking at a 20 foot run of RG-58 having 3.8 dB of loss and RG-142 3.2 dB, a
difference of 0.6 dB
So a true nit-picker would submit that the higher cost of RG-142 is not
worth it ..... but I submit it is much more rugged, and will last MUCH
LONGER compared to anything else.
Of course, the real advantage of RG-393 is that it will handle 10 Kw of
average power at 20 Mhz... needed when you are running a 3CX3000A7 with 7000
volts on the plate.
Take care Warren,
Mark
WA3JPY
________________________________
From: owner-yak-list-server@matronics.com on behalf of Warren Hill
Sent: Fri 7/6/2012 2:47 PM
Subject: Re: Yak-List: Antenna Yak52
Mark,
As you know, a straight 1/4 wavelength vertical radiator has a relatively
narrow bandwidth. The SWR will be good at 1/4 and possibly 5/8 wavelength,
but rises quickly after that. There is no way to make a single element
vertical antenna efficient from 118 to 136 MHz. It can be tuned at the
center frequency and we just have to accept the high SWR towards the ends of
the band. Also, the anodized aluminum panels on the CJ do not always conduct
well between each one.
The other weak point in aviation communications is the coax and the BNC
connectors. RG-58 is pretty lossy at 120 MHz and a poorly fashioned BNC
connector easily has a 1 to 2 dB insertion loss. For every 3 dB of loss the
signal strength is cut by 50%, outgoing and incoming. So... a non-resonant
antenna with a shaky counterpoise, two low quality, crimped BNC connectors
on RG-58 coax and even the best radio may seem less than adequate from 20
miles out.
The good news is that just about everything we do is line of sight and at
these frequencies it doesn't take much radiated power to maintain a
reasonable signal strength.
Warren
On Jul 6, 2012, at 11:17 AM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E wrote:
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> I might point out that physics is a problem here as well.
>
> One piece of metal as an antenna cannot be made to provide a
> characteristic impedance of 50 ohms from 118 to 136 MHz. You pretty
> much have to come up a way around that issue. :-)
>
> Mark
>
> p.s. Go ahead Brian.
>
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Hans Oortman
> Sent: Friday, July 06, 2012 4:23 AM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Antenna Yak52
>
>
> Thanks Mark....I can not reach the guts of the antenna myself but found
> a
> small guy who can.... Jan probably has still an antenna, so I'll wait
> what
> he can find.
>
> Buy the way: I hate matching networks, the only thing it does is match
> the
> impedance but pulls down the efficiency....
>
> I'll keep you posted!
>
> Hans
>
>
> Op 05-07-12 00:42, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
> <mark.bitterlich@navy.mil> schreef:
>
> Point,
>> MALS-14 64E" <mark.bitterlich@navy.mil>
>>
>> The stock Russian antenna has a small matching network inside. If you
> want to
>> go to the effort, the radiator can be replaced. It is actually a
> threaded
>> tapered rod. The best bet would be to ask around and see if you can
> find an
>> old one that someone removed that you can just thread in and be done.
>>
>> Personally, I took the antenna off, then drilled the original plate
> for a more
>> modern antenna and mounted it on the same plate. Doing it this way
> you really
>> should not notice any damage to your paint? In any case, you would
> have to
>> slice around the mounting plate so you could remove it. I think I
> have one
>> that I could take pictures of for you, but it would take a few days
> since I am
>> currently not home. If anyone else has pictures, I am sure that would
> help
>> you much better than this email.
>>
>> Mark
>>
>>
>> ________________________________
>>
>> From: owner-yak-list-server@matronics.com on behalf of Hans Oortman
>> Sent: Wed 7/4/2012 5:11 PM
>> To: yak-list
>> Subject: Yak-List: Antenna Yak52
>>
>>
>> Guys,
>>
>> Has anybody removed or swapped the antenna on a Yak52??
>> Mine is broken and completely corroded so needs to be replaced.
>> If I want to remove it, it means damaging the paint and I was
> wondering if
>> only the radiator could be removed rather than the whole assembly??
>> Pictures or drawings would be appreciated!
>>
>> Thanks!
>>
>> Hans O.
>> RA3326K
>> Netherlands
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
Message 6
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| Subject: | Re: Antenna Yak52 |
Mark;
Forgot to mention that due to questionable antennae and coax placement (not
much room in the CJ) I also installed a 1.????? GHZ notch filter at each
comm. Can't remember the number. Any comments?
Cheers;
Walt
-----Original Message-----
From: Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
Sent: Saturday, July 07, 2012 1:07 PM
Subject: RE: Yak-List: Antenna Yak52
MALS-14 64E" <mark.bitterlich@navy.mil>
Roger that Warren. As you know, the feedpoint impedance of a 1/4 wave
radiator is actually about 36 ohms, giving a best match of about 1.5 to 1
VSWR. Whereas in order to feed a 5/8 wave design, you try to make the 5/8
wave antenna appear to be about 3/4 wavelength which will establish a pretty
good match and also give the ideal low angle of radiation that can be gained
with the actual 5/8 wave length of the antenna. This is typically done by
using a base loading coil. Typical aircraft designs avoid 5/8 wavelength
due to the compressed pattern that is good for fixed stations, but bad for a
moving platform with pitch and roll.
Only really cheap avionics shops use RG-58 for the reasons you specified. A
much better alternative and what aircraft owners should specifically ask for
is RG-142 B/U which is a teflon dielectric silver tinned double shielded
coax that has a higher velocity factor than standard coax and thus lower
loss. This coax is good for short runs even at 1.5 GHz, such as a GPS
antenna for example. If more flexibility is needed in the coax (the teflon
is kind of stiff), I recommend RG-223, which is the same as RG-142, except
it has a poly dielectric rather than teflon.
If you are a warbird with LONG coax runs, I recommend RG-393/U which is the
roughly 0.5" variety of PTFE dielectric coax. It has even lower loss (large
center conductor) is also silver tinned. Again if stiffness is a factor,
the alternative is RG-214.
I recommend avoiding crimp on connectors of ANY type. Avionics shops love
them because they are easy and FAST to put on. Putting a standard BNC or
TNC connector takes time, and a little bit of soldering skill. That said, I
never ever use crimp-on's.
But just for giggles let's compare ....... A 20 foot run of RG-142 at 130
Mhz will give a loss of about 0.9 dB But with tongue in cheek, let me
also submit that a 20 foot run of RG-58 will have a loss of 1.0 dB, thus a
difference of only 0.1 dB. At 1500 Mhz, basically GPS range, you are
looking at a 20 foot run of RG-58 having 3.8 dB of loss and RG-142 3.2 dB, a
difference of 0.6 dB
So a true nit-picker would submit that the higher cost of RG-142 is not
worth it ..... but I submit it is much more rugged, and will last MUCH
LONGER compared to anything else.
Of course, the real advantage of RG-393 is that it will handle 10 Kw of
average power at 20 Mhz... needed when you are running a 3CX3000A7 with 7000
volts on the plate.
Take care Warren,
Mark
WA3JPY
________________________________
From: owner-yak-list-server@matronics.com on behalf of Warren Hill
Sent: Fri 7/6/2012 2:47 PM
Subject: Re: Yak-List: Antenna Yak52
Mark,
As you know, a straight 1/4 wavelength vertical radiator has a relatively
narrow bandwidth. The SWR will be good at 1/4 and possibly 5/8 wavelength,
but rises quickly after that. There is no way to make a single element
vertical antenna efficient from 118 to 136 MHz. It can be tuned at the
center frequency and we just have to accept the high SWR towards the ends of
the band. Also, the anodized aluminum panels on the CJ do not always conduct
well between each one.
The other weak point in aviation communications is the coax and the BNC
connectors. RG-58 is pretty lossy at 120 MHz and a poorly fashioned BNC
connector easily has a 1 to 2 dB insertion loss. For every 3 dB of loss the
signal strength is cut by 50%, outgoing and incoming. So... a non-resonant
antenna with a shaky counterpoise, two low quality, crimped BNC connectors
on RG-58 coax and even the best radio may seem less than adequate from 20
miles out.
The good news is that just about everything we do is line of sight and at
these frequencies it doesn't take much radiated power to maintain a
reasonable signal strength.
Warren
On Jul 6, 2012, at 11:17 AM, Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E wrote:
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> I might point out that physics is a problem here as well.
>
> One piece of metal as an antenna cannot be made to provide a
> characteristic impedance of 50 ohms from 118 to 136 MHz. You pretty
> much have to come up a way around that issue. :-)
>
> Mark
>
> p.s. Go ahead Brian.
>
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Hans Oortman
> Sent: Friday, July 06, 2012 4:23 AM
> To: yak-list@matronics.com
> Subject: Re: Yak-List: Antenna Yak52
>
>
> Thanks Mark....I can not reach the guts of the antenna myself but found
> a
> small guy who can.... Jan probably has still an antenna, so I'll wait
> what
> he can find.
>
> Buy the way: I hate matching networks, the only thing it does is match
> the
> impedance but pulls down the efficiency....
>
> I'll keep you posted!
>
> Hans
>
>
> Op 05-07-12 00:42, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
> <mark.bitterlich@navy.mil> schreef:
>
> Point,
>> MALS-14 64E" <mark.bitterlich@navy.mil>
>>
>> The stock Russian antenna has a small matching network inside. If you
> want to
>> go to the effort, the radiator can be replaced. It is actually a
> threaded
>> tapered rod. The best bet would be to ask around and see if you can
> find an
>> old one that someone removed that you can just thread in and be done.
>>
>> Personally, I took the antenna off, then drilled the original plate
> for a more
>> modern antenna and mounted it on the same plate. Doing it this way
> you really
>> should not notice any damage to your paint? In any case, you would
> have to
>> slice around the mounting plate so you could remove it. I think I
> have one
>> that I could take pictures of for you, but it would take a few days
> since I am
>> currently not home. If anyone else has pictures, I am sure that would
> help
>> you much better than this email.
>>
>> Mark
>>
>>
>> ________________________________
>>
>> From: owner-yak-list-server@matronics.com on behalf of Hans Oortman
>> Sent: Wed 7/4/2012 5:11 PM
>> To: yak-list
>> Subject: Yak-List: Antenna Yak52
>>
>>
>> Guys,
>>
>> Has anybody removed or swapped the antenna on a Yak52??
>> Mine is broken and completely corroded so needs to be replaced.
>> If I want to remove it, it means damaging the paint and I was
> wondering if
>> only the radiator could be removed rather than the whole assembly??
>> Pictures or drawings would be appreciated!
>>
>> Thanks!
>>
>> Hans O.
>> RA3326K
>> Netherlands
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
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