SB400 - Low Grid Drive on 40 Meters

[Kenneth G. Gordon]

On 13 Aug 2009 at 17:01, Mark Johnson wrote:

> Hi Ken, thanks for your input on this problem. In tune, on 80, 20, and
> 15, I can get full scale, or better on the grid current reading. On
> ten meters, about 1/4 to half scale. On 40, depending on where I am in
> the band, I get zero or slight movement on the grid current. As
> mentioned, on all bands,

Hmmmm.....that sure sounds familiar....but not with my SB-401. I 
have much the same problem in my SB-102....except that my low or 
no grid current reading occurs on the low end of 80.

According to the SB-401 manual, one should be able to achieve 
full-scale grid current in TUNE anywhere on any band, although 
lower on 10.

In my SB-102, the problem with low grid current on the low end of 
80 is related, but not completely so, to the fact that the 80 meter 
HET crystal has low output and/or is intermittant.

With my SB-401, I can peg the grid current meter anywhere on all 
the lower bands, at least. I have not tried that on 10.

When aligning my SB-401, I found that I could radically effect the 
grid current reading by adjusting the HET tuned circuits for that 
band.

BTW, the grid current should only be "peggable" in TUNE or CW. 
On SSB, the grid current meter may "kick" a bit on voice peaks, but 
should not show constant current.

Well, hang in there. Maybe something will come along here that 
addresses your problem directly.

vy 73,

Ken Gordon W7EKB

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