Nate,
My sincerest thoughts are with you in this time.
Don, KD9PT
- Original Message -
From: Nate Duehr
To: Repeater-Builder@yahoogroups.com
Sent: Tuesday, August 17, 2010 12:46 AM
Subject: Re: Properly designed PAs (was: Re: [Repeater-Builder] Coax length,
etc
To: Repeater-Builder@yahoogroups.com
Sent: Monday, August 16, 2010 10:46 PM
Subject: Re: Properly designed PAs (was: Re: [Repeater-Builder] Coax length,
etc.)
On Aug 15, 2010, at 7:06 AM, Jeff DePolo wrote:
Whoever said time is money was an idiot. Time is worth inifinitely times
On Aug 15, 2010, at 7:06 AM, Jeff DePolo wrote:
Whoever said time is money was an idiot. Time is worth inifinitely times
more than money. You can make more money. You can even borrow money.
Hell, if you were desparate you could even steal money. You can't do any of
those things with time.
On Aug 14, 2010, at 9:45 PM, Jeff DePolo wrote:
I disagree. I would accept the notion that the transmitter may not be
happy (and I put that in quotes not to mock you, but becuase I can't come
up with a better word either) because it is not *properly matched* when
looking into a 50+j0 load.
On Aug 14, 2010, at 9:45 PM, Jeff DePolo wrote:
Well, kinda. Many duplexers are spec'ed for 1.5:1 (14 dB RL) input VSWR
max. Fortunately, I rarely see any that are that bad. I'll gladly trade
off a tenth of a dB of insertion loss for several (if not 10 or more) dB of
return loss improvement
Hi Kevin:
Regarding temperature, our club has a site, no A/C or heat, where
temperatures inside the shelter can get below +20 deg F in winter, and
well over 130 deg F in the summer heat. I can't imagine filter tuning
not changing under such conditions, Invar or not. I can see over time
I don't know about that. Anritsu SiteMaster and CellMaster test sets
are fairly common test equipment available to cell techs here in
Connecticut. Whether they use them (or know how) is another thing.
Joe
On 8/15/2010 2:59 AM, Nate Duehr wrote:
What's up with the RF industry not buying
But why? If all of the power (or, let's hope, at least
99.99% of it)
is
on-channel, *should* a properly-designed and properly-functioning
transmitter misbehave due to the poor match a duplexer presents at
frequencies far removed from the channel center?
Well yes, properly
Actually I think that even though Service Monitors have
finally become *relatively* commonplace in the Ham Shack, the
VNA is not something most hams have seen or know how to use.
For $100, Rick's (Amtronix) return loss bridge is a must-have for anyone
that has a SM with a SA/TG. With it,
Jeff, out of all the PAs you've seen out there, both commonly
used and not-so-common... which ones (in your opinion) are
properly designed (when working right)?
I think a lot of them, generally speaking, are properly designed. That's
not to say that some of them don't have some downsides or
I've brought that issue up a few times, and usually get the blank radio shack
salesman type of stare.
-- Original Message --
Received: Sat, 14 Aug 2010 08:45:47 PM PDT
From: Jeff DePolo j...@broadsci.com
There is no simple rule of thumb, and if anybody tells you that there is,
ask
Russ,
Of course the Bird 43 does not measure power directly. But it does sample
voltage AND current on the line in amounts that are combined to indicate
power.
It is a directional coupler. The only time you will have a problem with it
deviating from its accuracy is when the directivity
Agreed!!
Mark - N9WYS
-Original Message-
From: Repeater-Builder@yahoogroups.com On Behalf Of Eric Lemmon
(major snippage)
This discussion is both informative and quite entertaining!
73, Eric Lemmon WB6FLY
I see some folks are heading for the Advil. My apologies.
Thanks, Gary, for admitting the 43 doesn't measure power directly. One
myth down.
Of course, it is a directional coupler, no argument. That makes it a
reflectometer, it enables the instrument to isolate forward/reflected
samples
Hi again Russ,
_
From: Repeater-Builder@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines
Sent: Sunday, August 15, 2010 4:54 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Coax length, etc.
I see some folks
, August 15, 2010 4:54 PM
*To:* Repeater-Builder@yahoogroups.com
*Subject:* Re: [Repeater-Builder] Coax length, etc.
I see some folks are heading for the Advil. My apologies.
Thanks, Gary, for admitting the 43 doesn't measure power directly.
One myth down.
Of course, it is a directional
Russ Hines wrote:
Hi Kevin:
Regarding temperature, our club has a site, no A/C or heat, where
temperatures inside the shelter can get below +20 deg F in winter, and
well over 130 deg F in the summer heat. I can't imagine filter tuning
not changing under such conditions, Invar or not. I
, August 15, 2010 7:37 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Coax length, etc.
Last round. Hi again, Gary. ;-)
On 8/15/2010 7:09 PM, Gary Schafer wrote:
Hi again Russ,
_
From: mailto:Repeater-Builder@yahoogroups.com
Repeater-Builder
I know I'm going to regret stepping into this one, but since when has that
stopped me before...
Thanks, Gary, for admitting the 43 doesn't measure power
directly.
What do you mean by measure power directly? If you're talking about
comparing a thruline measurement against
*From:* Repeater-Builder@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com] *On Behalf Of *Russ Hines
*Sent:* Sunday, August 15, 2010 7:37 PM
*To:* Repeater-Builder@yahoogroups.com
*Subject:* Re: [Repeater-Builder] Coax length, etc.
Last
Because the impedance is not matched between the transmitter
and duplexer, the 'apparent' loss of the duplexer is greater
than the manufacturers stated loss of the duplexer. Changing
the cable length is not changing the loss of the duplexer,
it's changing the power that is accepted at
: [Repeater-Builder] Coax length, etc.
Because the impedance is not matched between the transmitter
and duplexer, the 'apparent' loss of the duplexer is greater
than the manufacturers stated loss of the duplexer. Changing
the cable length is not changing the loss of the duplexer,
it's changing
On 8/14/2010 8:44 AM, Jeff DePolo wrote:
But if the duplexer is tuned to 50 ohms, and the cable is 50 ohms, varying
the cable length isn't going to change the Z seen by the transmitter. Or
are you suggesting the duplexer is purposely de-tuned from 50 ohms?
I use a Network Analyzer to tune
Jeff DePolo wrote:
Because the impedance is not matched between the transmitter
and duplexer, the 'apparent' loss of the duplexer is greater
than the manufacturers stated loss of the duplexer. Changing
the cable length is not changing the loss of the duplexer,
it's changing the power that is
Kevin Custer wrote:
Joe Ham buys a new duplexer and hooks it up to his 110 Watt MASTR II
repeater and gets 50 watts out the antenna port. He does his homework
and realizes that he should only be loosing 29%
Wow -* loosing -* that should have been losing - that's what I get for
being in a
Kevin Custer wrote:
I had one instance of a ham radio club loosing PA's left and right on
their 2M machine.
Indeed - I am loosing my mind - grin
K
-
From: Repeater-Builder@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com] On Behalf Of Kevin Custer
Sent: Saturday, August 14, 2010 10:15 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Coax length, etc.
Kevin Custer wrote:
Joe Ham buys a new duplexer
So will someone post a simple rule of thumb. If you have the option of
optimizing cable length from PA to first cavity, IE you haven't made
them yet what's the best simple rule of thumb to follow to build them
to avoid reactance. 1/2wl if allowed minus coupling loop depth? Or is
that past a simple
Subject: RE: [Repeater-Builder] Coax length, etc.
So will someone post a simple rule of thumb. If you have the option of
optimizing cable length from PA to first cavity, IE you haven't made
them yet what's the best simple rule of thumb to follow to build them
to avoid reactance. 1/2wl if allowed
That's because there are as many rules as there are thumbs. ;-)
I don't know about anyone else, but I can tell you about the highly
scientific method I use.
I start with a multiple of 1/2 electrical wavelength and trim as
necessary. I'd stay away from an odd-multiple of 1/4 wavelength in
Some related comments, if you don't mind.
Temperature changes seem to be the biggest detuner of largely
mechanical devices like cavity duplexers. We often send our repeaters
off to live in less-than-ideal environments, then expect cavity
input/output impedances to remain as we measured them
@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines
Sent: Saturday, August 14, 2010 4:30 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Coax length, etc.73
Some related comments, if you don't mind.
Temperature changes seem
Russ Hines wrote:
Some related comments, if you don't mind.
Temperature changes seem to be the biggest detuner of largely
mechanical devices like cavity duplexers. We often send our repeaters
off to live in less-than-ideal environments, then expect cavity
input/output impedances to remain
Ross Johnson wrote:
So will someone post a simple rule of thumb... If you have the option
of optimizing cable length from PA to first cavity, IE you haven't
made them yet what's the best simple rule of thumb to follow to
build them to avoid reactance. 1/2wl if allowed minus coupling loop
Jeff, you aren't stepping on my toes at all. Glad to see your
comments.
OK, good. Since you've never met me, I can assure you, you definately DO
NOT want me stepping on your toes, it would be painful.
I do have to agree with Kevin that most duplexer
manufacturers recommend different cable
So will someone post a simple rule of thumb. If you have the
option of optimizing cable length from PA to first cavity, IE
you haven't made them yet what's the best simple rule of
thumb to follow to build them to avoid reactance. 1/2wl if
allowed minus coupling loop depth? Or is that past
OK, I think, for the most part, we're on the same page. I'm cuttin' and
trimmin' a lot here...
And this is where I believe the duplexer manufacturers are
covering their butt. They don't want the problem with
complex reactance presented by the duplexer to be their
problem. Not that I
-Original Message-
From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
buil...@yahoogroups.com] On Behalf Of Jeff DePolo
Sent: Saturday, August 14, 2010 10:45 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: [Repeater-Builder] Coax length, etc.
Jeff, you aren't
I must have missed some posts - my inbox ran out of space (I'm on the road
and not checking email as often as I usually do), so my apologies if I'm
asking questions that have already been answered...
Allan Crites and I are currently in discussion which will
be used as the basis of a RB web
Jeff DePolo wrote:
Maybe I'm not understanding right. Are you saying that by varying the cable
length between the transmitter and the duplexer that you can affect the
insertion loss of the duplexer?
No.
Because the impedance is not matched between the transmitter and
duplexer, the
The cable length issue is a brother to if you don't like
your VSWR, change the point along the transmission line where
you're measuring it.
I don't know what that's supposed to mean. The VSWR on the line is the same
no matter where along the line you measure it. If you're using a meter
And a new perspective on transmission lines.
I didn't think it was worth responding to, Jeff.
AC WA9ZZU.
From: Jeff DePolo j...@broadsci.com
To: Repeater-Builder@yahoogroups.com
Sent: Fri, August 6, 2010 8:23:09 AM
Subject: RE: [Repeater-Builder] Coax length
Grab your Smith chart! LOL
- Original Message -
From: allan crites
To: Repeater-Builder@yahoogroups.com
Sent: Friday, August 06, 2010 12:46 PM
Subject: Re: [Repeater-Builder] Coax length, etc.
And a new perspective on transmission lines.
I didn't think
*To:* Repeater-Builder@yahoogroups.com
mailto:Repeater-Builder@yahoogroups.com
*Sent:* Fri, August 6, 2010 8:23:09 AM
*Subject:* RE: [Repeater-Builder] Coax length, etc.
The cable length issue is a brother to if you don't like
your VSWR, change the point along the transmission
Thanks, guys, a good topic and one that always seems to come up. And
it sparks more questions and comments, of course.
The cable length issue is a brother to if you don't like your VSWR,
change the point along the transmission line where you're measuring
it. By changing the length of the
Russ Hines wrote:
Thanks, guys, a good topic and one that always seems to come up. And
it sparks more questions and comments, of course.
The cable length issue is a brother to if you don't like your VSWR,
change the point along the transmission line where you're measuring
it. By changing
Thanks for the reply, Kevin. I'm looking forward to seeing the article.
73, Russ WB8ZCC
On 8/5/2010 1:20 PM, Kevin Custer wrote:
Russ Hines wrote:
Thanks, guys, a good topic and one that always seems to come up. And
it sparks more questions and comments, of course.
The cable length
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