Yaesu RSM-2 antenna
 

Hi, a friend of mine has a Yaesu RSM-2 10/80 metre antenna. He says it has
an SWR of around 3.7 MHz and wants to lower it for around 3.57 but the
adjustable tip doesnt affect it enough. Anyone got any tuning tips or
specs/instructions/comments?

Thankyou

Gary

Sorry, thats SWR of around 1.7:1 at 3.7 MHz...


"Gary Smith" wrote in message
...
Hi, a friend of mine has a Yaesu RSM-2 10/80 metre antenna. He says it has
an SWR of around 3.7 MHz and wants to lower it for around 3.57 but the
adjustable tip doesnt affect it enough. Anyone got any tuning tips or
specs/instructions/comments?

Thankyou

Gary

There is absolutely nothing wrong with a VSWR of 1.7:1!!!

W1MCE

Gary Smith wrote:

Sorry, thats SWR of around 1.7:1 at 3.7 MHz...


"Gary Smith" wrote in message
...

Hi, a friend of mine has a Yaesu RSM-2 10/80 metre antenna. He says it has
an SWR of around 3.7 MHz and wants to lower it for around 3.57 but the
adjustable tip doesnt affect it enough. Anyone got any tuning tips or
specs/instructions/comments?

Thankyou

Gary

Gary, the real question is how to change the frequency from 3.7 to 3.57 MHz?

I can't find the RSM-2 in the on-line Yaesu catalog or at HRO. Where can
I [we] find some online info on this antenna?

Deacon Dave, W1MCE
+ + +

If the thing tunes with a screw, buy a longer screw and replace the
one that's in there. If not, just add wire.

73 de AI8W, Chris

Dave Shrader wrote:

Gary, the real question is how to change the frequency from 3.7 to 3.57
MHz?

I can't find the RSM-2 in the on-line Yaesu catalog or at HRO. Where can
I [we] find some online info on this antenna?

Deacon Dave, W1MCE
+ + +

Gary, also be aware that if this is a mobile type antenna, that is ...
short compared to a 1/2 wavelength, then resonance is not indicated by
lowest VSWR. Resonance has nothing to do with VSWR. Resonance means the
frequency where there is no reactance.

The radiation resistance of short antennas on 80 meters can be as low as
4 ohms resulting in a VSWR of 12:1 at resonance!! Measure the antenna's
resonant frequency using an MFJ 259B or equivalent.

What you may need is an auto-tuner mounted at the antenna.

Deacon Dave, W1MCE

Gary Smith wrote:

Sorry, thats SWR of around 1.7:1 at 3.7 MHz...


"Gary Smith" wrote in message
...

Hi, a friend of mine has a Yaesu RSM-2 10/80 metre antenna. He says it has
an SWR of around 3.7 MHz and wants to lower it for around 3.57 but the
adjustable tip doesnt affect it enough. Anyone got any tuning tips or
specs/instructions/comments?

Thankyou

Gary

Amen and Amen! back in the early days of GPS (Then called the BRN-3 Transit
System) The transmit antennas has an SWR of 13:1. SWR meters will be
outlawed the day I take over as the world dictator.

I have never, ever, understood this preoccupation with SWR. I am guessing it
comes from the CB world where getting one's "SWR's down" was the holy
grail...
"Dave Shrader" wrote in message
news:YmEFb.426478$Dw6.1312140@attbi_s02...
There is absolutely nothing wrong with a VSWR of 1.7:1!!!

W1MCE

"w4jle" W4JLE(remove this to wrote in message
... I have never, ever, understood this
preoccupation with SWR. I am guessing it
comes from the CB world where getting one's "SWR's down" was the holy
grail...

When running low power, like CB'rs and QRP operators do, I can easily
understand the "preoccupation" with SWR. And when I used to run vacuum tube
transmitters in the USAF, SWR was important then too... high SWR levels were
not good for the finals.

Jerry
--
Jerry Bransford
To email, remove 'me' from my email address
KC6TAY, PP-ASEL
See the Geezer Jeep at
http://members.cox.net/jerrypb/

While a transmitter looking into an impedence mismatch can be a problem,
transforming the impedence the transmitter sees satisfies the transmitter
and has no effect on antenna SWR. Everybody's happy, nothing changes as far
as SWR.

An interesting exercise, compare an antenna cut so that is 1:1, change it so
that the SWR is now 3:1 and tell me what difference one would observe at the
receiving end.

You may use a tuner to match the transmitter to the newly adjusted antenna.


"Jerry Bransford" wrote in message
news:E2NFb.25033$gN.5459@fed1read05...
"w4jle" W4JLE(remove this to wrote in message
... I have never, ever, understood
this
preoccupation with SWR. I am guessing it
comes from the CB world where getting one's "SWR's down" was the holy
grail...

When running low power, like CB'rs and QRP operators do, I can easily
understand the "preoccupation" with SWR. And when I used to run vacuum
tube
transmitters in the USAF, SWR was important then too... high SWR levels
were
not good for the finals.

Jerry
--
Jerry Bransford
To email, remove 'me' from my email address
KC6TAY, PP-ASEL
See the Geezer Jeep at
http://members.cox.net/jerrypb/

"w4jle" W4JLE(remove this to wrote in message
...
While a transmitter looking into an impedence mismatch can be a problem,
transforming the impedence the transmitter sees satisfies the transmitter
and has no effect on antenna SWR. Everybody's happy, nothing changes as
far
as SWR.

Now you're changing things by adding a tuner... the net effect is that the
transmitter is now seeing a 1:1 swr. All we talked about was your claiming
there was a preoccupation with SWR... if there was no problem with a high
swr, then there's no need for the tuner you just inserted into your
justification.

There is and always will be a need to present the transmitter with the
lowest possible SWR, regardless of if it is accomplished with a well-tuned
antenna or if that is not possible, inserting an antenna tuner between the
transmitter and antenna. So you can't get away from a "preoccupation" with
SWR no matter what you like to think. :)

Jerry
--
Jerry Bransford
To email, remove 'me' from my email address
KC6TAY, PP-ASEL
See the Geezer Jeep at
http://members.cox.net/jerrypb/