I have this lowband Micor receiver
that I want to test for adjacent channel
rejection.
I have two calibrated signal generators
and a calibrated spectrum analyzer if
I need it.
How can i measure the rejection of the
off channel signal?
Thanks,
Tim
Hi Ralph,
Two things.
1. You are correct. A good memory is a plus. I went one step further and
created
a UNIX shell script to use the entire database of questions and test myself
over
a period of months on answers wrong vs time to take the entire test for each
class of license. When I got
VHF 128 channels. Programmed with CF-100 program software
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com]on Behalf Of Duane Hall
Sent: Thursday, July 22, 2010 1:05 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re:
Yep, blew the numbers. 97 for hams and 95 for the other services. That is
what
I get for not paying attention.
Around 1972 I took the comercial class exam. I thought I knew enough for the
second class at that time and it cost $ 1.00 more for the first class. Decided
that for only $ 1
The holy grail for FM performance testing, which includes adjacent channel
rejection measurements, is EIA/TIA-603. I believe revision C is the latest.
Unfortunately, you'll have to pay to get a copy of that document unless you
can scrounge one up.
To summarize how the test is done (and I'm
I have this lowband Micor receiver that I would like
to check the adjacent channel rejection.
I have two calibrated signal generators, and a calibrated
spectrum analyzer (if needed).
Can I do the measurements with this equipment?
If so, how? Resistor divider network between the
two sig gens?
Does anyone have a link to this? Would love it if this was in pdf as well ;-)
73,
Robert
KD4YDC
If you are attempting to verify a manufacturer's specification, the TIA-603
procedure should be used. If you are serious about that, you should probably
acquire TSB-88 in addition to TIA-603.
Here is a link to a presentation that discusses adjacent channel testing and
explains the roles of
Hi Nj902,
Well, I'm not trying to be exacting in the measurement, I'm just trying to
track down a desense issue in the system. I figured I'd look at how
the receiver does with the adjacent (transmitter) signal injected directly
into the rx input port.
The spectrum analyzer hooked up to the RX
Hi
you beat me to it, I would suggest a duplexer problem as -55dB
isn't a lot you should have ideally better than 80dB. It also could be
the fact that you are running too much tx pwr, have you tried dropping
it down.
73
Steve, M1SWB(UK)
- Original Message -
From: Tim tahr...@swtexas.net
The issue for repeater receiver desense is the same basic issue that affects
the bench test. For the bench test if the generator used for the adjacent
channel signal has too much phase noise - that noise will degrade the receiver
before the carrier level can be raised to the manufacturer's
Hi Steve,
Running 80 watts into the duplexer, getting 50 out.
Getting about 102dB notch out of the duplexers.
From a previous thread a couple of days ago, the
consensus was that -50 was fine for this receiver.
I hooked up my IC-706 to the TX port, and even
at 5w, I was getting significant
Hi 902,
Understand about the sideband noise, but I figured at a MHz away, it
probably wouldn't be an issue. Getting the same performance out of
both sides of the duplexer ... about 102dB notch 1.5dB attenuation.
Using RG142 for all interconnects, except from TX/RX to duplexer, and
those are
Been following this thread for a while, some thoughts in random order:
If I remember correctly you said that you are using the 1 5/8 heliax
notches as your duplexer.
If I also remember correctly others have reported problems of many
sorts with these homebrew devices.
While not an easy thing
Photo here:
www.repeater-builder.com/wa6ilq/Motorola-S-1350-C-WATT-METER-with-500W-500-1000-MHZ.jpg
Anybody know who made the watt meter in the photo for Moto ?
Did that company market it under their own name?
The HT220 switch handle on the right side is the
forward-reverse selector switch.
The HT220 is an element lock/release. The forward /reverse is the little
silver buttons on either side. I have one but not sure WHO make it for moto
On Sun, Jul 25, 2010 at 2:37 PM, Mike Morris wa6...@gmail.com wrote:
Photo here:
The power elements look like the same ones I have for my R2002
comm analyzer.
Tim
I'm going to start working on building a link for a remote receiver. I already
have a voter and I'll be using a VHF Micor receiver strip for the remote.
A couple of mobiles that tune down to 420 might be good as I don't have a lot
room. I'm thinking the link transmitter will be keyed 7x24 with
Hi again Tim
what you could try is this, put a signal gen on the tx port and see
what the isolation is on the rx port, don't forget to put a dummy
50ohm load on the ant port
Steve
- Original Message -
From: Tim tahr...@swtexas.net
To: Repeater-Builder@yahoogroups.com
Sent: Sunday, July
Hi
you beat me to it, I would suggest a duplexer problem as -55dB
isn't a lot you should have ideally better than 80dB. It also could be
the fact that you are running too much tx pwr, have you tried dropping
it down.
73
Steve, M1SWB(UK)
He said he measured the Tx carrier at the Rx
Hi
OH right 30w loss is not right. You maybe getting -102db notch
but it is the isolation between the tx an rx ports that count, you need
better than 80db. I know of some 6mtr repeaters in the UK that
use the heliax duplexers and get better than -90db isolation with
insertion losses a round 1.5dB.
Hi Jeff
yes I know -55db is I think around 399 microvolts which will flatten
any receiver, he needs to know the actual isolation between the tx
and rx ports. I assume that the notch figure Tim mentions is the actual
notch of each filter, which is why in my later mail I suggested doing
an
Robert,
I have good news and bad news. The bad news is that the R2200-series
Operator's Manual 6881069A79 is out of print and is NLA. The good news is
that the R2200A Maintenance Manual 6991069A76 is still available from
Motorola Parts, for about $58.
73, Eric Lemmon WB6FLY
-Original
Hi Jeff
yes I know -55db is I think around 399 microvolts
No, you're still missing it. He said -55 dBm (m = milliwatts), not -55 dB.
which will flatten any receiver
-55 dBm at 1 MHz offset isn't going to bother any half-decent receiver. A
decent receiver would have 100 dB of
Allow me to show my age ...
To me, the HT-220 is/was a Xtal Controlled Ht !!
The Forward/Reverse switch is the buttons on the
side. The flat knob on the right is the element
locking mechanism.
I have three of these and a box full of elements.
They are quite accurate, equaling a Bird 43. The
On 7/25/2010 2:37 PM, Mike Morris wrote:
Photo here:
www.repeater-builder.com/wa6ilq/Motorola-S-1350-C-WATT-METER-with-500W-500-1000-MHZ.jpg
Anybody know who made the watt meter in the photo for Moto ?
I believe this was a Motorola fabricated item. It was also used with
several
I'm in the exact same boat working on a remote receiver. I don't want
the link keyed 24-7 either. I now there are some voters out there that
don't require 1950hz and some that don't need it present 100% of the
time to keep that voter port active. But are there any other voters in
the used or DIY
Tim,
It appears to me that your measurement procedure is correct - and that the
results you have gotten would normally be sufficient isolation to allow
desense-free duplex operation.
If you have some attenuators available - or better yet - a switchable [in 1 dB
increments] attenuator - there
The S-1350 wattmeter was designed by an RF engineer at the Motorola Schaumburg
Parts Department and was built at the Motorola Schaumburg Parts Department.
The RF power calibration standards for RF certifications of the S-1350 were
supplied by the Motorola Schaumburg Instrumentation Department to
On Sun, 25 Jul 2010 19:34:58 -0700
Ross Johnson kc7...@comcast.net wrote:
I'm in the exact same boat working on a remote receiver. I don't want
the link keyed 24-7 either. I now there are some voters out there that
don't require 1950hz and some that don't need it present 100% of the
time to
Hello Mike.
I am not sure who made it for Motorola but they did use the frequency knob
from the portables to lock the
The sensor is/was designed to be left in the feedline and all you have to do
is slide the sensor into the meter, lock it in place and you are ready to
go. I used to have one of
Hi Nj,
Thanks for the info. That's one test I'll be trying tomorrow.
I did a bit of snooping in the IF chain with a scope probe
my spectrum analyzer, and found that at the back end of the
xtal filter chain/amplifiers, I saw two signals, one a MHz above
the desired receive frequency, and it was
sorry it has taken so long for me to get back with you. Can you tell me
about the cabinets you have available., size, do they have rack mounts, etc.
I actually may be able to get someone to stop in CA a help me get one or I
may be able to get someone to drive me down.
Larry
-Original
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