[Amps] Henry 4 K-2 SWR

[K8MLM@aol.com]

Bud,
 
It may be just the extra coax you are putting in the line between the  
exciter and amplifier.  As you said, the SWR goes up as the frequency goes  up.  At 
low frequencies, the amplifier and coax represents  a small addition.  At high 
frequencies, (6 meters) it may be a  significant addition.
 
Where is the SWR bridge?  Is it in the exciter or at the output of the  
amplifier?  I suspect it's at the exciter.  Does the SWR change to 1:1  if you re 
tune the SteppIR when the amplifier and extra coax are in the  line?
 
Remember the articles on how your length of Coax will vary the SWR that  your 
exciter will see.  One must consider the entire system from the SWR  bridge 
(in the exciter, amplifier, or outboard) to the antenna, regardless  of the 
fact that one might think the coax line is "flat."
 
Bob
K8MLM
 
In a message dated 12/7/2005 8:47:20 P.M. Eastern Standard Time,  
w3ll at arrl.net writes:

When  passing thru the Henry 4 K-2 amp, with the amp turned off,  the exciter 
 sees an SWR of between 1.1 to 2.0 depending 
on the band the exciter is set  on (75M thru 10M). The SWR is higher at the 
higher frequencies. The SWR is  infinitely 
high on 6M.

If connected directly to the antenna(s), the  exciter sees 1.1 SWR on all 
bands. I'm using a SteppIR antenna whose  
elements can be tuned to present a flat impedance at any frequency between  
40M and 6M.

With the amp turned on, the exciter sees an SWR of 1.1 on  all bands (75M to 
10M).

My question is why does the amp introduce a  higher SWR in bypass and not 
allow a 6M signal to pass thru without  
introducing an infinitely high SWR?

In the off position, the signal  passes thru an input bypass relay and then 
to an internal SWR bridge at the  output side 
of the amp and then to the antenna.

With the amp turned  on, the signal passes thru the input relay and to the 
appropriate band input  impedance matching 
module. This explains the 1.1 SWR on all bands with the  amp turned on.

The only components in the path, with the amp turned  off, is the bypass 
relay and the SWR bridge - all internal to the 
amp. Can  these be causing the exciter to see the higher SWR and infinite 6M 
SWR? Is the  internal SWR bridge the culprit? 
Any ideas?

73,

Bud  W3LL
w3ll at arrl.net