[NLRS] TR-751 Output Spike?

Thu, 16 Jan 2003 01:11:28 cst

I don't know about a power spike, but I did find this info
about a voltage spike. It was in Feed Point July/Aug 1993.

    " WB5LBT has been having problems with his 751 blowing
out GaAs FET preamps. It seems that the DC switching pulse
to the Pin Diodes is passed down the coax. The typical GaAs FET
preamp has a .01 MFD coupling cap followed by a 4 to 1 transformer.
The .01 passes the pulse, and the transformer steps up the voltage.
If you don't like the VJB tuned output, at least change the coupling
cap to only a few hundred pF."

It must be one heck of a big, long spike to show up on a Bird Wattmeter.
They have a rather long time constant.

73, Gary  WB0LJC

On Wed, 15 Jan 2003 19:51:12 -0600 "Bud Patten"
<[email protected]> writes:
>Hi Gang,
>I just purchased a Kenwood TR-751A and was poking around the internet 
>for
>possible mods to the rig.  I ran across the following message from 
>Zack Lau
>and wondered if any of you guys who are running the '751 as an IF rig 
>have
>noted this problem?
>
>Bud
>w0lcp
>
>--------- Begin forwarded message ----------
>From: "Zack Lau" <[email protected]>
>Subject: Kenwood TR-751 power spike
>Date: Tue, 02 Sep 1997 19:31:56 -0400
>
>I was going to use my TR-751A for QRP portable use,
>but haven't been able to eliminate the full
>power spike that occurs when you let up on the mic
>button when you are in USB--so I get 29 watts on
>the Bird PEP meter, even in the low power position.
>Doesn't appear to be a problem on CW or FM,
>but I wouldn't run the rig into a brick
>or transverter unless it could handle the
>29 watt power spikes. --Zack W1VT  FN33kd in Sept VHF test
>
>
>
>Please check out my Web Site:  www.qsl.net\w0lcp
>and the Northern Lights Radio Society website at:
>http://nlrs.dropboxone.net/index.htm
>
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>[email protected]
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>

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