SB-400 Question:

[Eddy Swynar]

Mark & Dave...

Alas & alack, I found the same to be so with my old SB-400...try as I might,
I could NEVER get it to honk out anywhere even NEAR the magic "100 watts" on
10-meters.

I even resorted to fiddling with the final pi-tank coil for the
6146's---adding a bit of extra lead-in wire, to shorting half turns, all to
no avail. As I recall, I ran the whole gamut of adjustments & re-adjustments
on the 6CL6 driver stage, too, to no good effect.

As Mark says, chalk one up for design intent! I guess one simply must learn
to live with it. I think ALL the Heath "SB" transmitters & transceivers were
like this, to a greater or lesser extent...

~73~ Eddy VE3CUI - VE3XZ




---- Original Message -----
From: "Mark Johnson/Ontario/IBM" <mjohnson at CA.IBM.COM>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Monday, November 12, 2001 6:19 PM
Subject: Re: SB-400 Question:


> 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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