[Amps] Henry 4 K-2 SWR

Bud Governale w3ll at arrl.net
Wed Dec 7 20:46:33 EST 2005


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






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