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Old June 26th 04, 09:25 PM
RB
 
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Default inline swr meter question

I have a very nice ham SWR meter that was bought in '74 timeframe in the
electronics district in Tokyo. It is an inline Osker Block unit (never
heard of 'em). I would like to use it, and think I can. But, need an
understanding of how it works first, and this is what I'm seeking help on.

It appears it is designed for 75m-2m ops.

The unit is well built, and is a metal box approx 3" square on the ends, and
8" across the front. It has coax fittings on each end. There is a
75ohm/50ohm selector switch by one of the coax fittings. There are separate
power and SWR panel meters in the box.

There is a calibration chart that is obviously used in conjunction with a
small control device which is knob adjustable. It may be a var cap, or a
variable resistor (pot). The calibration card has two control setting
scenarios: one for 50 ohms, and one for 75 ohms.

The calibration card has different control settings for different power
levels at the same freq.

I ASSUME the cal card setpoints are supposed to give me approx 0 meter
reading if the xmtr signal is seeing close to 1:1 SWR. Is this likely
correct?

And yes, I could easily rig things, using a coax switch, to where I could
take comparative readings between the Osker and my normal SWR meter, and do
a cut and try thing. However, it would be an inconvenience to have to do
this. And, I figure there are people in this group who probably have the
info I'm looking for at hand.


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Old June 26th 04, 10:16 PM
jason
 
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Default

Hello,

First switch it to 50 ohms as that's what CB's use. While you hold the mic
button in and transmit, put the meter to SET or CAL and adjust so the needle
goes to the SET/CAL mark on the scale. Switch it to REF or reflected and it
will show the SWR reading.
You need to adjust it if you change power by the way !

"RB" wrote in message
...
I have a very nice ham SWR meter that was bought in '74 timeframe in the
electronics district in Tokyo. It is an inline Osker Block unit (never
heard of 'em). I would like to use it, and think I can. But, need an
understanding of how it works first, and this is what I'm seeking help on.

It appears it is designed for 75m-2m ops.

The unit is well built, and is a metal box approx 3" square on the ends,

and
8" across the front. It has coax fittings on each end. There is a
75ohm/50ohm selector switch by one of the coax fittings. There are

separate
power and SWR panel meters in the box.

There is a calibration chart that is obviously used in conjunction with a
small control device which is knob adjustable. It may be a var cap, or a
variable resistor (pot). The calibration card has two control setting
scenarios: one for 50 ohms, and one for 75 ohms.

The calibration card has different control settings for different power
levels at the same freq.

I ASSUME the cal card setpoints are supposed to give me approx 0 meter
reading if the xmtr signal is seeing close to 1:1 SWR. Is this likely
correct?

And yes, I could easily rig things, using a coax switch, to where I could
take comparative readings between the Osker and my normal SWR meter, and

do
a cut and try thing. However, it would be an inconvenience to have to do
this. And, I figure there are people in this group who probably have the
info I'm looking for at hand.




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Old June 26th 04, 10:16 PM
jason
 
Posts: n/a
Default

Hello,

First switch it to 50 ohms as that's what CB's use. While you hold the mic
button in and transmit, put the meter to SET or CAL and adjust so the needle
goes to the SET/CAL mark on the scale. Switch it to REF or reflected and it
will show the SWR reading.
You need to adjust it if you change power by the way !

"RB" wrote in message
...
I have a very nice ham SWR meter that was bought in '74 timeframe in the
electronics district in Tokyo. It is an inline Osker Block unit (never
heard of 'em). I would like to use it, and think I can. But, need an
understanding of how it works first, and this is what I'm seeking help on.

It appears it is designed for 75m-2m ops.

The unit is well built, and is a metal box approx 3" square on the ends,

and
8" across the front. It has coax fittings on each end. There is a
75ohm/50ohm selector switch by one of the coax fittings. There are

separate
power and SWR panel meters in the box.

There is a calibration chart that is obviously used in conjunction with a
small control device which is knob adjustable. It may be a var cap, or a
variable resistor (pot). The calibration card has two control setting
scenarios: one for 50 ohms, and one for 75 ohms.

The calibration card has different control settings for different power
levels at the same freq.

I ASSUME the cal card setpoints are supposed to give me approx 0 meter
reading if the xmtr signal is seeing close to 1:1 SWR. Is this likely
correct?

And yes, I could easily rig things, using a coax switch, to where I could
take comparative readings between the Osker and my normal SWR meter, and

do
a cut and try thing. However, it would be an inconvenience to have to do
this. And, I figure there are people in this group who probably have the
info I'm looking for at hand.




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