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Today's Topics:
1. Collins filter ([EMAIL PROTECTED])
2. Re: Pi-Net vs Link Couple ([EMAIL PROTECTED])
3. Re: Pi-Net vs Link Couple (ronnie.hull)
4. RE: Pi-Net vs Link Couple (Brett gazdzinski)
5. Re: Pi-Net vs Link Couple (Geoff)
6. Re: Pi-Net vs Link Couple ([EMAIL PROTECTED])
7. Re: Pi-Net vs Link Couple (ronnie.hull)
8. Re: Pi-Net vs Link Couple (ronnie.hull)
9. Re: Pi-Net vs Link Couple (Geoff)
10. Re: Pi-Net vs Link Couple (Geoff)
----------------------------------------------------------------------
Message: 1
Date: Thu, 22 Sep 2005 04:19:26 EDT
From: [EMAIL PROTECTED]
Subject: [AMRadio] Collins filter
To: amradio@mailman.qth.net
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset="US-ASCII"
I am looking for the 6.0khz filter..Pt # F-455-J60.. for the
Collins 75A4
Reciever...Tnx Ron W6MAU
------------------------------
Message: 2
Date: Thu, 22 Sep 2005 07:37:13 -0400
From: [EMAIL PROTECTED]
Subject: Re: [AMRadio] Pi-Net vs Link Couple
To: Discussion of AM Radio <amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=US-ASCII
On 21 Sep 2005 at 21:45, Geoff wrote:
> I've heard recently that matching the output of the Class C
> pate-modulated final to the antenna is better, and more efficiently
> achieved by link coupling, vs Pi-Net.
Where did you hear that?
> On the other hand, it's argued
> that Pi-Net coupling produces less RFI than link coupling does.
>
> So, which is better?
Pi Network.
> Why?
I can only tell you from my own experiences, that a) You already
answered the foirst part - less harmonics, and
B) you get more power out.
That is enough to persuade me.
I know some folks swear by link coupling.
I swear at it!
I had an Eldico rig once with an 807 final.
I could only get about 15 watts out with the link coupling.
I re-confiugred it to be a pi network and immediately had
no diifficulty getting about 35 watts out.
Now some may argue that the link coupling circuit wasn't
made right, wasn't adjust right etc. etc. I don't care about
that. I just like pi networks. If it was good enough for
Art Collins...
------------------------------
Message: 3
Date: Thu, 22 Sep 2005 07:53:13 -0400
From: "ronnie.hull" <[EMAIL PROTECTED]>
Subject: Re: [AMRadio] Pi-Net vs Link Couple
To: "Mike Dorworth, K4XM" <[EMAIL PROTECTED]>, Discussion of AM
Radio
<amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=iso-8859-1
Mike I'm the fellow that is going to build up a Class C final using
a 450TL.
I would love to get a copy of that schematic for the 450TH rig in
the Editors
and Engineers handbook. I have a few of those, but apparently, not
that one.
I have a very nice B&W 850A or 852 that I can use in this rig.
Either should
handle that tube fine, considering I'm not going to run much more
than 2500
volts on it anyway. Maybe 3000.
I just got the worled biggest honker daddy plate transformer from
W5OMR.
8200V center tapped ( 4100 - 0 - 4100 ) at 4.5KVA !!! Yeah suh,
takes 3 men
and a dolly to move it!!
This will be a fun project.
73's & batten down the hatches, here comes Rita..
W5SUM
---------- Original Message -----------
From: "Mike Dorworth,K4XM" <[EMAIL PROTECTED]>
To: "Discussion of AM Radio" <amradio@mailman.qth.net>
Sent: Wed, 21 Sep 2005 23:10:59 -0400
Subject: Re: [AMRadio] Pi-Net vs Link Couple
> The Pi-Net will give a total of 50 db suppresion of harmonics.
about
> 20 in one spot and 30 in the other. Link couple can pass harmonics
> to VHF by capacity coupling, hence the Faraday Shield Links used
for
> same later on. There is a nice single 450th Pi-Net rig shown in
the
> Editor and Engineers handbook. Also a couple of single ended ones
in
> the 1950 ARRL Handbook (for triodes). Some triodes that require
> lots and lots or drive can unbalance the grid tank, which is
> required for triodes using Pi-Net. Lo capacity tubes like the
450th
> is OK. The old timers mostly used tuners (antenna) and open wire
> feeders to keep the harmonics down. Hazletine link neutralization
> can also be used and no split tanks are needed in or out. Remember
> Class C , which is required for Hi level AM, is a extreme
distortion
> and harmonic generator so that some plan need to be in place to
> handle the soup. Also a single band dipole is very frequency
> selective and cuts way down on harmonics by itself. Multiband
> dipoles, beams and multi dipole on one feeder and traps etc (G5RV)
> are an open invitation to spread gook with only link output. Also
> the guys that use CB lin years with no half wave filters get away
in
> mobile service without too many problems due to the narrow
> frequency discrimination of mobile antennas. Hope this helps, 73
Mike
>
> ----- Original Message -----
> From: "Geoff" <[EMAIL PROTECTED]>
> To: "Discussion of AM Radio" <amradio@mailman.qth.net>
> Sent: Wednesday, September 21, 2005 10:45 PM
> Subject: [AMRadio] Pi-Net vs Link Couple
>
> > SO, here we are, well past 1991 and the 'law' that went into
effect
> > saying that 1,500w PEP output is the maximum RF Power output
that we
> > hams can run, regarldless of mode. That doesn't deter the
homebrewing
> > spirit, but it does suggest that acheiving 1,500w PEP output is
much
> > easier than producing 1kW DC input to the final. With the
mindset of
> > still wanting to use the classic high-level plate modulation
scheme,
> > engineering a rig to use only one tube in the final (a 4-250,
250TH,
> > 304TH/TL, 4-400, etc), modulated by a pair seems to make more
common
> > sense. That, and it's a bit more economic in filament
requirements.
> >
> > I've heard recently that matching the output of the Class C
> > pate-modulated final to the antenna is better, and more
efficiently
> > achieved by link coupling, vs Pi-Net. On the other hand, it's
argued
> > that Pi-Net coupling produces less RFI than link coupling does.
> >
> > So, which is better?
> >
> > Why?
> >
> > What are the effects of nuetralizing a single tube in a balanced
tank
> > circuit? If Pi-Net is to be used, does the final tube still
need to be
> > nuetralized?
> >
> > I know of a guy who wants to build a rig using a single 450TL in
the
> > final, modulated by a pair. He wants to pi-net the output, but
I've
> > heard that's a bad idea.
> >
> > I want to build a rig using a medium powered tride, perhaps a
250TH,
> > modulated by a pair of 811's. Pi-Net, or Link Couple?
> >
> > I like seeing this kind of technical discussion on the list.
I'm
> > looking forward to all inputs.
> >
> > --
> > 73 = Best Regards,
> > -Geoff/W5OMR
> >
> > ______________________________________________________________
> > AMRadio mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/amradio
> > Help: http://mailman.qth.net/mmfaq.html
> > Post: mailto:AMRadio@mailman.qth.net
> > AMfone Website: http://www.amfone.net
> > AM List Admin: Brian Sherrod/w5ami
> >
>
> ______________________________________________________________
> AMRadio mailing list
> Home: http://mailman.qth.net/mailman/listinfo/amradio
> Help: http://mailman.qth.net/mmfaq.html
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> AM List Admin: Brian Sherrod/w5ami
------- End of Original Message -------
------------------------------
Message: 4
Date: Thu, 22 Sep 2005 08:13:51 -0400
From: Brett gazdzinski <[EMAIL PROTECTED]>
Subject: RE: [AMRadio] Pi-Net vs Link Couple
To: 'Discussion of AM Radio' <amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=US-ASCII
I don't think there is any way to run a triode single ended with
link
coupled
output, not in class C.
I run a pair of 812A's (or 811A's, or V70D's) push pull link coupled
output
modulated by a pair of 811A's.
It works very well.
You can run them up to 2000 volts on the plates, or 1750, 0r 1500.
I can get 400 watts carrier out pushing them, 350 watts out has the
tubes
showing no color.
That is very close to the legal limit with plenty of audio.
The 812/811 tubes are cheap, work from 1000 to 2000 volts, and
don't take up a lot of space.
I used small vacuum variable caps for neutralization, kilowatt
coils, and a 6000 volt plate tuning cap.
I got the small (2 to 30 pf @30,000 volts) neut caps out of old
paging
transmitters someone gave me, they ran a 4-400 at 3000 volts on 70?
MHZ.
Brett
N2DTS
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Geoff
Sent: Wednesday, September 21, 2005 10:46 PM
To: Discussion of AM Radio
Subject: [AMRadio] Pi-Net vs Link Couple
SO, here we are, well past 1991 and the 'law' that went into effect
saying that 1,500w PEP output is the maximum RF Power output that we
hams can run, regarldless of mode. That doesn't deter the
homebrewing
spirit, but it does suggest that acheiving 1,500w PEP output is much
easier than producing 1kW DC input to the final. With the mindset
of
still wanting to use the classic high-level plate modulation scheme,
engineering a rig to use only one tube in the final (a 4-250, 250TH,
304TH/TL, 4-400, etc), modulated by a pair seems to make more common
sense. That, and it's a bit more economic in filament
requirements.
I've heard recently that matching the output of the Class C
pate-modulated final to the antenna is better, and more efficiently
achieved by link coupling, vs Pi-Net. On the other hand, it's
argued
that Pi-Net coupling produces less RFI than link coupling does.
So, which is better?
Why?
What are the effects of nuetralizing a single tube in a balanced
tank
circuit? If Pi-Net is to be used, does the final tube still need to
be
nuetralized?
I know of a guy who wants to build a rig using a single 450TL in the
final, modulated by a pair. He wants to pi-net the output, but I've
heard that's a bad idea.
I want to build a rig using a medium powered tride, perhaps a 250TH,
modulated by a pair of 811's. Pi-Net, or Link Couple?
I like seeing this kind of technical discussion on the list. I'm
looking forward to all inputs.
--
73 = Best Regards,
-Geoff/W5OMR
______________________________________________________________
AMRadio mailing list
Home: http://mailman.qth.net/mailman/listinfo/amradio
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:AMRadio@mailman.qth.net
AMfone Website: http://www.amfone.net
AM List Admin: Brian Sherrod/w5ami
------------------------------
Message: 5
Date: Thu, 22 Sep 2005 07:22:16 -0500
From: Geoff <[EMAIL PROTECTED]>
Subject: Re: [AMRadio] Pi-Net vs Link Couple
To: Discussion of AM Radio <amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=us-ascii; format=flowed
ronnie.hull wrote:
> <>Mike I'm the fellow that is going to build up a Class C final
using
> a 450TL.
> I would love to get a copy of that schematic for the 450TH rig in
the
> Editors
> and Engineers handbook. I have a few of those, but apparently, not
> that one.
>
> I have a very nice B&W 850A or 852 that I can use in this rig.
Either
> should
> handle that tube fine, considering I'm not going to run much more
than
> 2500
> volts on it anyway. Maybe 3000.
>
> I just got the worled biggest honker daddy plate transformer from
W5OMR.
> 8200V center tapped ( 4100 - 0 - 4100 ) at 4.5KVA !!! Yeah suh,
takes
> 3 men
> and a dolly to move it!!
I think you're going to find, and we talked about this, that the
transformer is 4100v across the entire secondary (@4.74kVA)
------------------------------
Message: 6
Date: Thu, 22 Sep 2005 08:41:26 -0400
From: [EMAIL PROTECTED]
Subject: Re: [AMRadio] Pi-Net vs Link Couple
To: Discussion of AM Radio <amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=US-ASCII
On 22 Sep 2005 at 7:22, Geoff wrote:
> > I just got the worled biggest honker daddy plate transformer
from W5OMR.
> > 8200V center tapped ( 4100 - 0 - 4100 ) at 4.5KVA !!
> I think you're going to find, and we talked about this, that the
> transformer is 4100v across the entire secondary (@4.74kVA)
Yeah but 8200 volts sounds so... electrifying!
If anyone needs a smaller tranny, I have one that will do 2500 volts
at about 1 amp.
Brian, AF4K
------------------------------
Message: 7
Date: Thu, 22 Sep 2005 09:05:28 -0400
From: "ronnie.hull" <[EMAIL PROTECTED]>
Subject: Re: [AMRadio] Pi-Net vs Link Couple
To: Discussion of AM Radio <amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=iso-8859-1
well it clearley shows on the top of the tranny 4100 - 0 - 4100..
I'll test
it out this weekend and we'll know then.
did you ever even put power to this transformer?
R
---------- Original Message -----------
From: Geoff <[EMAIL PROTECTED]>
To: Discussion of AM Radio <amradio@mailman.qth.net>
Sent: Thu, 22 Sep 2005 07:22:16 -0500
Subject: Re: [AMRadio] Pi-Net vs Link Couple
> ronnie.hull wrote:
>
> > <>Mike I'm the fellow that is going to build up a Class C final
using
> > a 450TL.
> > I would love to get a copy of that schematic for the 450TH rig
in the
> > Editors
> > and Engineers handbook. I have a few of those, but apparently,
not
> > that one.
> >
> > I have a very nice B&W 850A or 852 that I can use in this rig.
Either
> > should
> > handle that tube fine, considering I'm not going to run much
more than
> > 2500
> > volts on it anyway. Maybe 3000.
> >
> > I just got the worled biggest honker daddy plate transformer
from W5OMR.
> > 8200V center tapped ( 4100 - 0 - 4100 ) at 4.5KVA !!! Yeah suh,
takes
> > 3 men
> > and a dolly to move it!!
>
> I think you're going to find, and we talked about this, that the
> transformer is 4100v across the entire secondary (@4.74kVA)
>
> ______________________________________________________________
> AMRadio mailing list
> Home: http://mailman.qth.net/mailman/listinfo/amradio
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:AMRadio@mailman.qth.net
> AMfone Website: http://www.amfone.net
> AM List Admin: Brian Sherrod/w5ami
------- End of Original Message -------
------------------------------
Message: 8
Date: Thu, 22 Sep 2005 09:06:33 -0400
From: "ronnie.hull" <[EMAIL PROTECTED]>
Subject: Re: [AMRadio] Pi-Net vs Link Couple
To: Discussion of AM Radio <amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=iso-8859-1
well Bry, you gotta unnerstand, I'm next door to Texas, that makes
me a
cousin.. and you know how they are in texas.. everything is
bigger!!!
R
---------- Original Message -----------
From: [EMAIL PROTECTED]
To: Discussion of AM Radio <amradio@mailman.qth.net>
Sent: Thu, 22 Sep 2005 08:41:26 -0400
Subject: Re: [AMRadio] Pi-Net vs Link Couple
> On 22 Sep 2005 at 7:22, Geoff wrote:
>
> > > I just got the worled biggest honker daddy plate transformer
from
W5OMR.
> > > 8200V center tapped ( 4100 - 0 - 4100 ) at 4.5KVA !!
>
> > I think you're going to find, and we talked about this, that the
> > transformer is 4100v across the entire secondary (@4.74kVA)
>
> Yeah but 8200 volts sounds so... electrifying!
>
> If anyone needs a smaller tranny, I have one that will do 2500
volts
> at about 1 amp.
>
> Brian, AF4K
>
> ______________________________________________________________
> AMRadio mailing list
> Home: http://mailman.qth.net/mailman/listinfo/amradio
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:AMRadio@mailman.qth.net
> AMfone Website: http://www.amfone.net
> AM List Admin: Brian Sherrod/w5ami
------- End of Original Message -------
------------------------------
Message: 9
Date: Thu, 22 Sep 2005 09:01:35 -0500
From: Geoff <[EMAIL PROTECTED]>
Subject: Re: [AMRadio] Pi-Net vs Link Couple
To: Discussion of AM Radio <amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
ronnie.hull wrote:
> <>well it clearley shows on the top of the tranny 4100 - 0 -
4100..
> I'll test
> it out this weekend and we'll know then.
>
> did you ever even put power to this transformer?
>
> R
Yes, I did. Did it at John/WA5BXO's place.
------------------------------
Message: 10
Date: Thu, 22 Sep 2005 09:03:49 -0500
From: Geoff <[EMAIL PROTECTED]>
Subject: Re: [AMRadio] Pi-Net vs Link Couple
To: Discussion of AM Radio <amradio@mailman.qth.net>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=us-ascii; format=flowed
ronnie.hull wrote:
> <>well Bry, you gotta unnerstand, I'm next door to Texas, that
makes me a
> cousin.. and you know how they are in texas.. everything is
bigger!!!
>
> R
Bry, just on the Off-chance that I might make it to Florida, what
are
you asking for that 2500v @ 1amp xfmr?
--
73 = Best Regards,
-Geoff/W5OMR
------------------------------
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End of AMRadio Digest, Vol 20, Issue 33
***************************************
