[Heathkit] HW-104 finals

[JBA]

Hi Roger!
I have used the MRF- 450A as well as the MRF-455A. Both work fine. I 
actually prefer the MRF-450A ( a little stouter than the originals and 
about $5.00 apiece cheaper that the MRF-455A ) . Solid 100-115 watts 
output across the bands. I've put them into seven or eight units with no 
problems. I currently have three SB-104/A here in the shack, all with 
the MRF-450A.
I used to try to follow Heath's advice and stay with matched sets only, 
but through the years I have found that it doesn't matter much about 
being matched. If the Beta numbers are anywhere close you should be fine.
The MRF-450A are also a direct replacement for the originals---no mods 
needed.
FYI------ I use the MRF-314A for the drivers. Never had a problem with 
them either. They're a little pricey, but I've never blown one.
Both are available at RF Parts.
My friend Kees Talen has an excellent site dealing with the 104's that 
includes among other things, a great schematic marked up with RF voltages.

http://www.qsl.net/k5bcq/sb104/sb104.html

Hope this helps,
Cheers!
Benton  wb5twc



KC8OPP Roger S. wrote:
> Hello List,
>
> Two HW-104's and a SB-104 came into the shack for
> repair last week.  So far one of each is working just
> fine with minor repairs and alignment.  Now it is down
> to the last HW-104 and it has bad transistors in the
> PA board.  With the PA board from the other 104 the
> rest of the rig works FB.
>
> I know I have one bad final transistor for sure and
> the other three are questionable.  Installed is the
> CD2664A and the manual list the 2N6456 as a sub.  I
> have seen reference to the MRF455A also being used in
> HW-104's.
>
> Anyone replaced the finals in a HW-104/SB-104?  What
> did you use, where did you get them, any gotchas I
> should look out for?  I have found the 2N6456 at RF
> Parts but not in a matched quad. So before I spend the
> money for repair, let me know what you did.
>
> Thanks for the input in advance.
>
> 73's
> Roger
> KC8OPP
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam protection around 
> http://mail.yahoo.com 
> _______________________________________________
> List Administrator: Duane Fischer, W8DBF        
> ** For Assistance: dfischer at usol.com **         
> $$ See the vintage area on the HCI web site - http://www.w9wze.org $$ 
> Heathkit mailing list
> Heathkit at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/heathkit
>
>
>   


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.394 / Virus Database: 268.9.8/380 - Release Date: 6/30/2006