[Heath] HeathKit SB-300

[Guy Giacopuzzi]

Some thoughts.....Have you checked the tubes associated with the tuned 
circuits that are tuning weirdly?  Or better yet done replacements with 
known good/new ones?  But if this is/just/ associated with the 10 and 15 
meter bands, and as you said, the coils were damaged, getting a shot--a 
photo--of a known, unmolested coil would allow you to perhaps rewind the 
coils per spec.  At the moment, I don't have any 301's handy to open up, 
but if someone else on the list doesn't respond, let me know....I have, 
I think two 301's...and I'm not sure of the diff's between the 301 and 
300....I don't have any 300's.....Remember too to suspect the xtal's as 
I've had xtal's go bad--10 meter one's incidentally--on my 303'....and 
there, I'm afraid, the only substitute besides one off a donor rig, is 
one of those synthesis xtal replacements, which, with the need to power 
them, are a real hassle in a vintage rig...

Guy

WA6OQQ


On 6/30/2018 1:56 PM, Bob wrote:
> I recently restored a HeathKIt SB-300. The 15 and 10 meter front end 
> coils were severely damaged. I was able to repair them using epoxy. 
> The 15 meter circuits now peaks when tuned and the crystal calibrator 
> signal is an S-9, but I am still having issues with 10 meters. The 
> coils peak but the crystal calibrator signal on 10 meters is on S-3 as 
> best. I replaced the 68pf silver mica cap with a known good one. Also 
> the peak across the four 10 meter segments occur at different 
> positions on when peaking the preselector, as an example 28 MHz peaks 
> with the capacitor almost fully closed, but the 28.5 peaks with the 
> capacitor almost fully open. The 29 Mhz peaks mid range. Seems odd. I 
> have seen where some are reporting that on 10 meters they get 20 dB 
> over S-9 using the calibrator. Also if I leave the 15 meters ant coil 
> peaked I get oscillation, so I have had to back it off slightly from 
> peak. I suppose I could install a choke similar to the SB-301.
>
> As background I have replaced all resistors, electrolytic caps and 
> disc/silver mica that I found where open. There is no AC ripple and 
> all other circuits are operating as designed. When operated on 80-15 
> the calibrator readings range from 3-20 dB over S9. Any thoughts very 
> much appreciated. I tried to use SB-301 coils replace the damaged 
> SB-300 coils, but the 301 coils have different spacing requirements.
>
> Any thoughts on resolving this issue would be appreciated. Also if you 
> have an SB-300 parts unit I would like to get the coils.
>
> 73
>
> Bob, W8RLC
>
>
> _______________________________________________
> Heath mailing list
> Heath at puck.nether.net
> https://puck.nether.net/mailman/listinfo/heath
>
>

-- 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://puck.nether.net/pipermail/heath/attachments/20180630/4f2404a6/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 2012email_signature.jpg
Type: image/jpeg
Size: 117949 bytes
Desc: not available
URL: <https://puck.nether.net/pipermail/heath/attachments/20180630/4f2404a6/attachment-0001.jpg>