Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
----------------------------------------------------------------------
Another way of doing this is described by Al Parker, W8UT at
(http://www.thecompendium.net/radio/filtercap.htm#Drake)
Yet another effective, while not "original" option is at
(http://www.wb4hfn.com)
which appears to be down at the moment. It's a small PC board that fits
over the chassis "hole" left when the original cap is removed.
73, Garey - K4OAH
Chicago
Dennis Monticelli wrote:
Hi Jason,
I left the can in place and just disconnected it. Fresh radial caps
were mounted on a small homemade PCB underneath the chassis. You need
to use small modern caps in order for the board to fit. While I was
in there, I went ahead and replaced the other electrolytics under the
chassis (as a preventive) even though none of them were showing any
signs of trouble. I consider replacing the big can the only must-do
if you're experiencing hum problems. The other electrolytics are
exposed to less stress.
Denny AE6C
On 11/22/05, *Jason Buchanan* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Dennis Monticelli wrote:
> Hi Jason,
>
> I also noted that CW notes were hum modulated in my
R4B. Because you
> remember better performance in the past, perhaps the big can is
going
> south on you? I have only worked on two Drakes (a 4A and a 4B) and
> both of them needed can replacement. Post replacement, both radios
> still had finite residual hum, though much improved from before. My
> R4B is no longer modulating CW notes. After a doubling of the
> capacitance of the first filter section, the hum is now inaudible.
>
> See my earlier post regarding the 4B and Garey's suggestions for
> alleviating headphone hum.
>
> Look for a bulge in the PS can or a hotter than normal can or
> excessive ripple on the filter sections. The first filter section
> (across the raw DC) is hammered by the most ripple current and
can be
> expected to fail first due to localized heat buildup. If the
measured
> voltage ripple is much more than about 8Vpp, it should be replaced.
> While you're in there, I would replace the other (less stressed)
> sections at the same time.
>
> Denny AE6C
hi - thanks for the advice. Can you point me in the right
direction of
the components I should replace? The big can near the transformer
is an
obvious one (although i'm afraid it won't be replaced with one
that is
so pretty looking - these new can electrolytics are black and ugly hi)
but I don't know what others I should target. I can solder well, just
not sure what other places will need to be retooled inside the R4B.
Same for the T-4XB but I think i'll take care of the biggest problem
areas with the AC-4 rebuild.
Thanks,
Jason
----------------------------------------------------------------------
Submissions: [email protected]
Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost: [EMAIL PROTECTED] - help in body of message
Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net
----------------------------------------------------------------------
