Re: [IC-7000] What is typical IC-7000 output/SWR question


Craig Pitcher
 

John,

Thanks for going to all that trouble..

I think I will talk to Icom. When you buy a used rig, you take your chances.

Craig

-----Original Message-----
From: ic7000@yahoogroups.com [mailto:ic7000@yahoogroups.com] On Behalf Of
John Kramer
Sent: Monday, May 06, 2013 9:43 AM
To: ic7000@yahoogroups.com
Subject: Re: [IC-7000] What is typical IC-7000 output/SWR question
Importance: High

Craig

Right, I pulled my spare 7000 out the closet and did some tests, here are
the results:

Band tests were done on: 40 meters
- At 13.8 volts I reached max forward power - 115 watts
- When I start lowering the voltage, power starts to drop off immediately
from 13.7 volts and below, however it is a very gradual drop. I have to get
down to 12.76 volts before it drops (from 115 watts) down to 100 watts, and
then drops rapidly if the voltage goes below 12.76 volts
- SWR - yes it is very sensitive. At 1.1:1 and 1.2:1 it is at full 115
watts. It starts to drop off on output power from 1.3:1. When I introduce an
SWR of 1.6:1 the power has gone down to 100 watts (from 115 watts)

So in conclusion, as long as your SWR is below 1.5:1, and your voltage is
above about 13 volts, you will get more than 100 watts out the rig. 13.8
volts and an SWR of below 1.2:1 will give the full 115 watts.

That is on my 7000, this one bought in the USA about 2 years ago

73
John, ZS5J






On 06 May 2013, at 6:13 PM, John Kramer <jkramer@iafrica.com> wrote:

Craig, you are right. If it is starting to fold back at an SWR of
1.2:1 or 1.3:1, then that does sound over sensitive. I have not
checked mine, but I would think that it only starts to fold back on
power after 1.5:1. I will do some tests and let you know at what point it
starts to cut back.

Regarding sensitivity to voltage, yes, it is very sensitive, but 13.8
volts should be plenty for full output. I will also do some tests to
see at what voltage my 7000's start to drop in power. I do know that
the 7000's that are in my mobiles, they run at reduced power output
when my vehicle is switched off, or when the alternator is not
charging. I can immediately see when the alternator kicks in, as the
power bumps up..although it doesn't bother me too much, I use it as it
is. Some guys have bought the MFJ gadget that goes in line with the power
cables, and keeps the voltage at a steady 14 v regardless of wether the
alternator is on or off.

From a happy owner of 3 x IC-7000's

73
John, ZS5J




On 06 May 2013, at 5:25 PM, Craig Pitcher <cpitcher@verizon.net> wrote:

Jim and Milo,

Thanks for your comments. I think my real question got lost. What I
was asking was is it normal for the 7000 SWR power reduction feature
to reduce the power so much when the SWR only goes from 1.1 to 1.3 to
1? Seems like a reduction of 20-25 watts at that kind of SWR is
excessive. I could understand this if the SWR was high, like 1.8, but
1.2 or 1.3 is a decent SWR, and as good as you can get on many antennas..

To Milo's point about an extra 5 watts or so does not make much
difference is true, but an extra 20-30 is the difference between
being heard, or not heard by a DX station.

I made the comment about voltage as a result of reading several posts
on the
7000 needing higher voltage than the 13.8 that my power supply was
set to produce.

For the record, I use a Bird 43P with a 100 watt slug (peak reading
meter), and an RF Applications P-3000 computerized SWR/Wattmeter.
They read within a few watts of each other.

Thanks, but I still don't know whether the power reduction is typical
or if mine is over sensitive.

Craig

-----Original Message-----
From: ic7000@yahoogroups.com [mailto:ic7000@yahoogroups.com] On
Behalf Of Milo Austin
Sent: Monday, May 06, 2013 7:04 AM
To: ic7000@yahoogroups.com
Subject: Re: [IC-7000] Re: What is typical IC-7000 output/SWR
question

Hi Craig,

I'm going to go out on a limb here, so forgive me ahead of time if I
sound a little harsh. Several good and important points have already been
covered.
But what jumped out at me was your statement that you didn't know
what your car's alternator put out. Now I'm not saying that this
information is terribly important in this case. What I am saying is
that this seems to indicate a lack of very basic skill and understanding.

Maybe instead of focusing on squeezing out the very last watt, you
should focus on the fundamentals. And one of those fundamentals you
should already know is, if you are transmitting at even 75 watts, or
especially 96 watts instead of 100, the person at the other end is
NOT going to be able to tell one bit of difference. I don't have the
figures in front of me, but the difference in power received versus
the small change in transmit power is negligible. It's pretty much
accepted if you can get even 1.3 or better VSWR especially from a
mobile antenna and over a range of frequencies, consider yourself
lucky. If you really want to squeeze the best SWR from your antenna,
start looking at a means to match your antenna, not upping the voltage to
14.

As a rule, I never run my 7000 at full power, though it certainly is
laudable to look for the best possible efficiency (lowest SWR)
regardless of the power level. The less concern you have about that
last 5 watts is the longer your finals will last also. Operating
mobile tends to increase the chance for unknown or uncontrolled
circumstances that might prove catastrophic at maximum power. And
always, ALWAYS check your VSWR at a much reduced power first, the
lowest power that will produce a reliable SWR reading, since you have
no clue for sure what it is going to be. And if you need to do
extensive antenna testing, invest in an antenna analyzer and save the
world from having to listen to your whistles across the band.
Much less than 100 (even 5 or 10) watts can be heard around the world
under the right conditions.

73, Milo
KF5GCF

On Mon, May 6, 2013 at 12:26 AM, Jim <w8lgz@yahoo.com> wrote:

**




Hi Craig,

You don't mention a couple points needed to help with your problem;
that's what mode you're using, and what type of meter you're using
to
test.

First, never try to get an accurate reading of your radios power out
into an antenna (Unless you know for fact you have perfect VSWR and
little to no loss on the feed line, which almost never happens in
most installs; always use a 50 Ohm dummy load.

Second, you should (for ease of testing and to get a proper reading)
always use CW mode to get a fairly accurate measurement (most meters
have a 5%-10% tolerance +/-). If you have performed your tests in CW
mode and are showing 96 watts as you said, I wouldn't worry about it.
If you're testing in SSB and showing 70-80 watt peaks on an average
reading meter (should always use a quality peak/hold meter for SSB)
again, I wouldn't worry about it. Chances are very good your radio
is
producing proper power out.

Jim, W8LGZ




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