SB-400 Question:

[Mark Johnson/Ontario/IBM]

Hi Dave....I struggled with the same problem..With replacing ALL tubes, and
a very careful alignment I got 80-15 up to about 100-90 watts and the four
10 meter bands were a comprimise at about 30 to 50 watts. I finally picked
the exact mid point of the 10 meter band , did the alignment and got a
reasonable power spread over the band.....Example, 1st 10 meter band at 35
watts, next band at 40 watts, next (mid point) 50 watts, last band, 35
watts...Never got full 80 watts out across the band....I did what you did,
measured grid drive, all DC voltages, etc.....Never found a specifc
problem...I had that rig on the bench countless times scoping, and
hunting......Finally resigned myself to "working as designed".......I also
had the optional crystal pack installed so I never had to test/trouble
shoot with the SB-300 hooked up....

Rig works OK, made many many contacts on CW & SSB...on all bands.....

Please let me know how you make out and maybe share what responses you get
on this note.....

Mark V. Johnson
VE3DJU/VE3DDI


"Kechkaylo Dave (ATLINKS)" <KechkayloD at TCE.COM>@LISTSERV.TEMPE.GOV> on
11/12/2001 04:55:16 PM

Please respond to "Kechkaylo Dave (ATLINKS)" <KechkayloD at TCE.COM>

Sent by:  Heathkit Owners and Collectors List <HEATH at LISTSERV.TEMPE.GOV>


To:   HEATH at LISTSERV.TEMPE.GOV
cc:
Subject:  SB-400 Question:


To All:

I have a question about my SB-400. I went thru the entire alignment, but
the
RF output power seems low: 100W on 80, 90W on 40, 80W on 20, 70W on 15,
then
down to about 50W on 10M. The RF dummy load and wattmeter both check out
fine on other rigs.

The RF on pin 2 of the 6CL6 driver is 2 to 4 VRF, and I'm able to get
anywhere from 45 to 60VRF on the final grids. The 6146s are new, matched
units, but other 6146s give the same result. The high voltage is 765 VDC
key
up, 706VDC key down; plate current 260 down to 210mA, depending on band.

The unit seems to load up right into a 50-ohm load, and other than this, it
operates fine, with the exception of the lower than anticipated RF output.

Can anyone on this list offer any suggestions? The SB-400 is used
stand-alone; i.e., it is not tested with the matching SB-300.

Regards,

Dave Kechkaylo, W8DLK/9

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