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Author Topic: Johnson Viking Valiant Zero Beat-SOLVED  (Read 2912 times)
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w3khg
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« on: January 14, 2019, 06:25:34 AM »

Not hearing the zero beat in the receiver when the Oscillator switch is turned to ZERO. In order for me to hear the zero beat I put the transmitter at full output which is not good for the receiver!

john
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MikeKE0ZUinkcmo
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« Reply #1 on: January 14, 2019, 07:11:08 AM »

This is from a write-up for the ranger, but the two transmitters are virtually identical in their design up through the multiplier stage, so this should apply.

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Mike KE0ZU

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w3khg
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« Reply #2 on: January 22, 2019, 09:28:56 AM »

Could it possibly be a weak tube in the Valiant not allowing me to hear the signal when the oscillator is put into ZERO? When transmitting I do have full power output and all else is well with the transmitter.
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WD8BIL
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« Reply #3 on: January 22, 2019, 09:43:05 AM »

Not really familiar with the Valiant but check the key jack for closure. Stick a key in it and send some dits.
My Viking, in the Phone mode, needs it.

Just a guess.
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w3khg
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« Reply #4 on: January 22, 2019, 10:30:59 AM »

Not really familiar with the Valiant but check the key jack for closure. Stick a key in it and send some dits.
My Viking, in the Phone mode, needs it.

Just a guess.

Appreciate the reply but it did not help. Now my Ranger II requires the key but the Valiant doesn't.
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WE1X
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« Reply #5 on: January 22, 2019, 11:28:57 AM »

John,

I use my Valiant with a 75A-3 and I don't always hear the zero beat either. However, I use Buffer, Zero and AM selections and tune the VFO to the receiver frequency by peaking the 75A-3's meter.  Gets me pretty darn close.

Harry
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w3khg
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« Reply #6 on: January 22, 2019, 11:36:10 AM »

What I discovered is the buffer MUST be peaked in order to hear the Oscillator's Zero beat signal in a receiver. This signal is very weak as it is and if the buffer is slightly off you will not hear the signal.
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w3khg
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« Reply #7 on: January 23, 2019, 10:38:42 AM »

The following was sent to me by K7PP, Pete, who is very knowledgeable when it comes to the Johnson Transmitters. This explains why I was having trouble hearing the Zero Beat signal in the receiver. Hope this helps others having the same issue.

Hi John;
There is nothing wrong with your transmitter.  This problem is very pronounced on 160 and 75 meters.
The Val is so well filtered that there isn't much signal leaked that is available to be used to zero beat.  I found
that some days I had enough signal to zero beat and others it was impossible.   This is due to the noise
level and what it does to the AGC.   If you disconnect the antenna from the receiver or if the noise level on any
particular day is low then there is enough signal to zero beat.
I can tell you how I solved my issue although you might find it a bit "Mickey Mouse".
I installed a "T" fitting on the receiver input of my 75A-4 and took a coaxial jumper over to the
SSB coax input jack on the Valiant. 
Problem solved. 
There is enough leaked signal on the input jack to dramatically increase the zero beat signal.

Pete
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