: 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 inif
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
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 tim
Either way, I give up.
73
Gary K4FMX
*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:*
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 absorptive/cal
nt: Sunday, 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>
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 can
, 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 direct
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 are
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 t
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
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 becomes
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"
>
> There is no simple rule of thumb, and if anybody tells you that there is,
> ask them how do you
> 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 downside
> 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
> 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, prope
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 thes
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
whe
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 improveme
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 lo
> -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
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
> 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 ca
> 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 tha
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
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 remai
er-Builder@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
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 the
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
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
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 simpl
Original Message-
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 buy
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 -
K
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
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
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
FWIW,
TX/RX Systems talks about "adverse length" cable between the transmitter and
the duplexer in their technical papers.
Chuck
WB2EDV
- Original Message -
From: "Jeff DePolo"
To:
Sent: Saturday, August 14, 2010 8:44 AM
Subject: RE: [Repeater-Build
> 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 a
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 'apparen
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 we
On Aug 5, 2010, at 11:20 AM, Kevin Custer wrote:
> Allan Crites and I are currently in discussion which will be used as the
> basis of a RB web article that will explain exactly what is happening, why it
> happens, and why an 'optimized' cable length can be used to transfer power
> ending up w
Subject:* Re: [Repeater-Builder] Coax length, etc.
And a new perspective on transmission lines.
I didn't think it was worth responding to, Jeff.
AC WA9ZZU.
*From:* Jeff DePolo mailto:j...@broadsci.com>
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 i
And a new perspective on transmission lines.
I didn't think it was worth responding to, Jeff.
AC WA9ZZU.
From: Jeff DePolo
To: 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 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 me
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 issu
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 changin
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
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