SWR Question

[George-122]

Q # 1:  My homebrewed single 3-500 tube linear has no tuned imput circuit.  When I drive it with my K2, the K2 is working into about 3:1 swr, and indicates HI REF, but seems to suffer no harm.  Is that too high an SWR, and does this condition lower the quality/purity of the transmitted signal??  Will it do harm to the K2?

Q # 2:  If I used an Elecraft antenna tuner, would it resolve the problem and lower  the fig to 1:1??  Or does the tuner only work with antennas at the other end?

Q# 3:  Any idea how the tuner in the Icom Pro 3 would handle the same situation?

Still having lots of fun with the K2 after 2 yrs.

Tnx,
 N4YM  (K2 #4758)
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[Don Nesbitt]

Q#1 Constantly running the K2 into 3:1 SWR not a good idea.  It will work
(for how long?) but will work a lot better (and perhaps longer?) into a
better match.

Q#2 Yes, in all likelihood, the antenna tuner (antenna tuners do not "tune"
the antenna - they just provide impedance matching between the rig and the
load) will provide the needed impedance match for a near unity SWR.

Q#3 The antenna tuner in the Icom 756 Pro III should handle the impedance
match.  At least mine will.  Give it a try.  73 es gud dxing -- Don N4HH

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of George
Sent: Thursday, April 19, 2007 12:27 PM
To: [hidden email]
Subject: [Elecraft] SWR Question

Q # 1:  My homebrewed single 3-500 tube linear has no tuned imput circuit.
When I drive it with my K2, the K2 is working into about 3:1 swr, and
indicates HI REF, but seems to suffer no harm.  Is that too high an SWR, and
does this condition lower the quality/purity of the transmitted signal??
Will it do harm to the K2?

Q # 2:  If I used an Elecraft antenna tuner, would it resolve the problem
and lower  the fig to 1:1??  Or does the tuner only work with antennas at
the other end?

Q# 3:  Any idea how the tuner in the Icom Pro 3 would handle the same
situation?

Still having lots of fun with the K2 after 2 yrs.

Tnx,
 N4YM  (K2 #4758)
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[w9cf]

As long as you back down the power appropriately I think you will be fine.
However, your amplifier would work better if you put, for example,
a pi network at the input. This will give a low impedance path for the
second and higher harmonic energy in the input circuit and improve the
efficiency. You can then adjust it for a better input match. It also makes
the amplifier input impedance less sensitive to the drive level.

One problem with using an antenna tuner is that, since it is not designed
to give a low impedance path for the harmonic energy, it may or may not
do so.  This may or may not effect the amplifier operation. It may even
make the input impedance more sensitive to the drive level. On the other
hand, you might get lucky.

73 Kevin w9cf

>Q # 1:  My homebrewed single 3-500 tube linear has no tuned imput circuit.  
>When I drive it with my K2, the K2 is working into about 3:1 swr, and indicates
>HI REF, but seems to suffer no harm.  Is that too high an SWR, and does this
>condition lower the quality/purity of the transmitted signal??  Will it do harm
>to the K2?
>
>Q # 2:  If I used an Elecraft antenna tuner, would it resolve the problem and
>lower  the fig to 1:1??  Or does the tuner only work with antennas at the other
>end?
>
>Q# 3:  Any idea how the tuner in the Icom Pro 3 would handle the same situation?
>
>Still having lots of fun with the K2 after 2 yrs.
>
>Tnx,
>N4YM  (K2 #4758)

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