Hello All,

A general aviation pilot friend of mine brought me a wattmeter with an
adjustment between the wattmeter and the swr meter. It ranges between
0 and 10. The only marks of identification are Mura CBM-30. So my
questions are..

1. What is the darn adjustment for?

2. What frequency range is for? VHF would be ideal...

Thanks in advance for any information,
Chris
N1UOC

"Chris" wrote:
A general aviation pilot friend of mine brought me a wattmeter with an
adjustment between the wattmeter and the swr meter. It ranges between
0 and 10. The only marks of identification are Mura CBM-30. So my
questions are..

1. What is the darn adjustment for?

2. What frequency range is for? VHF would be ideal...

It sounds like an inexpensive SWR meter for CB use. It will work on ham
freqs below 30 MHz. Probably will be inaccurate at VHF.

There should be a FWD/REV switch on it. Put the switch in the FWD position
and key up your rig. Set the adjustment to full scale. Then, switch to REV
and read yer SWR. If it's the type I think it is, it will only give a
relative power indication, not actual watts.

Art N2AH

On Tue, 11 Jan 2005 18:16:40 -0500, "Arthur Harris"
wrote:


"Chris" wrote:
A general aviation pilot friend of mine brought me a wattmeter with an
adjustment between the wattmeter and the swr meter. It ranges between
0 and 10. The only marks of identification are Mura CBM-30. So my
questions are..

1. What is the darn adjustment for?

2. What frequency range is for? VHF would be ideal...

It sounds like an inexpensive SWR meter for CB use. It will work on ham
freqs below 30 MHz. Probably will be inaccurate at VHF.

There should be a FWD/REV switch on it. Put the switch in the FWD position
and key up your rig. Set the adjustment to full scale. Then, switch to REV
and read yer SWR. If it's the type I think it is, it will only give a
relative power indication, not actual watts.

Sorry Art,
There is no FWD/REV switch. That is what the SWR side of the meter is
for. There is no need to reverse the meter and sense the reflected
power.

But as far as it being for CB/HAM, other folks had the same idea. And
it will not be accuarate up in the airband.

As an added note, I have pulled the back off and there is a straight
rod between the in and the out so-239s. Running parrallel are two
more rods used for sensing. Wires run from the sensing rods to the
pot in the middle. Actually it is a double pot. So might it be some
sort of attenuator or ballence....but I would guess that should be a
cap....I dunno....that is why I asked you guys.

Again thanks Art for taking a stab at it...
Chris


Art N2AH

"Chris" wrote in message
...
On Tue, 11 Jan 2005 18:16:40 -0500, "Arthur Harris"
wrote:


"Chris" wrote:
A general aviation pilot friend of mine brought me a wattmeter with an
adjustment between the wattmeter and the swr meter. It ranges between
0 and 10. The only marks of identification are Mura CBM-30. So my
questions are..

1. What is the darn adjustment for?

2. What frequency range is for? VHF would be ideal...

It sounds like an inexpensive SWR meter for CB use. It will work on ham
freqs below 30 MHz. Probably will be inaccurate at VHF.

There should be a FWD/REV switch on it. Put the switch in the FWD
position
and key up your rig. Set the adjustment to full scale. Then, switch to
REV
and read yer SWR. If it's the type I think it is, it will only give a
relative power indication, not actual watts.

Sorry Art,
There is no FWD/REV switch. That is what the SWR side of the meter is
for. There is no need to reverse the meter and sense the reflected
power.

But as far as it being for CB/HAM, other folks had the same idea. And
it will not be accuarate up in the airband.

As an added note, I have pulled the back off and there is a straight
rod between the in and the out so-239s. Running parrallel are two
more rods used for sensing. Wires run from the sensing rods to the
pot in the middle. Actually it is a double pot. So might it be some
sort of attenuator or ballence....but I would guess that should be a
cap....I dunno....that is why I asked you guys.

Again thanks Art for taking a stab at it...
Chris


Art N2AH

You seem to have the deluxe version with 2 meters but without FWD/REV
switch.
While transmitting, use pot to adjust power meter to full scale, then read
SWR on other meter.

A general aviation pilot friend of mine brought me a wattmeter with an
adjustment between the wattmeter and the swr meter. It ranges between
0 and 10. The only marks of identification are Mura CBM-30. So my
questions are..

1. What is the darn adjustment for?

2. What frequency range is for? VHF would be ideal...


Does it look like the one at:

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=5744258400
&category=48699

If so, then its for CB radio and won't work for VHF.


Ed