[Heathkit] SB-304

[kiyoinc at attglobal.net]

I got the SB-303 recap kit from Tom (www.hayseedhamfest.com) 
yesterday.     Hey thanks Tom! 

These caps are the proper axials.

The big 2200 and the other XICONs have a black stripe on the side marked 
" -  -  -".  One end of the cap is black.   Does that mean that's the 
"minus" end?


The other caps, the Nichicons,  have "-" arrows pointing to one end.   
That's the "minus" end of the cap, correct?  


I had been stalled on an SB-303 project for a while for a couple 
reasons.  This 303 has a low level AC hum in spite of replacing the main 
capacitor.

I'm guessing one of my 500 ufd electrolytics is bad.  Given that 303's 
are 30+ years old, it's not a bad idea to do a total recap of the 
electrolytics.    I started a couple times to order a full set of caps, 
quantity 100 or 250, with the idea of selling off the excess as kits.


I was overjoyed that Tom stepped up to the plate so that I would not 
have to do that.


I've been much too sick to take on a project like ordering and rebagging 
a couple thousand capacitors, advertising them, taking orders and 
mailing them.   I'm doing a better but still, given this economy, I'm 
focussed on my day job.    Don't know if anyone here has noticed but the 
economy has gotten kinda weird.


Any of you with a '303 or '313, Tom has the caps.   Get em while their 
hot!!!


Back to this '303.  

I've got a series of reversible upgrades planned for mine.  Some of this 
is experimental and might not work out but we'll see.

1) The recap using Tom's kit,  get rid of the AC hum.


2) Clean the LMO and get it stable.  The '303's LMO is capable of a few 
cycles per hour stability.   These radios are amazing.


3) Lead shot in the main tuning knob.  Makes it smooth.


4) Polish the knobs and the visible plastic.  Paint the cabinet to 
freshen up the look. 


5) Tighten the bandpass.   I have a '303 with two 2.1 ssb filters in 
series.  Cuts down the blowby a lot. I have some ideas for doing this at 
a low cost.


6) Open up the bandpass.   I have a '313 with the 5 kHz AM filter.   I'd 
like a 10 kHz AM filter.   I've heard there's an LC filter mod.  That 
would be better for the '313.


7) PSK31 and other digital modes on the back panel.   If it's all done 
in software, is the '303 stable enough?  Morse code, RTTY, slowscan, etc. 


8) Digital readout inside the 303.  
http://www.qrpkits.com/freqcounter.html has a small counter.  Not as 
sophisticated as the AADE but the price is nice.   It might fit in the 
[1...2...3...4...5] window.   I'd only put it inside if it were 
reversible, otherwise I'd put it in a small Heath looking station 
control box.


I'd call a radio with all the mods an SB-304. 


de ah6gi/4