0.005pF is unreasonably small.
My money is on uF.
On 25-Feb-10 23:09, Chuck Grandgent wrote:
Hey Garey,
did you mean uF or pF. Richrd is quite certain you really meant pF.
Chuck, K1OM
On Thu, Feb 25, 2010 at 2:38 PM, Garey Barrell<[email protected]> wrote:
Richard -
OK. That 0.005 cap isn't particularly critical. The 1000 ohm resistor is
the load, the cap is just to prevent shorting the DC to ground. Any disc
ceramic from 0.001 to 0.01 uF at 500V or more would work just fine.
I wouldn't worry too much about the calibrator. As long as someone hasn't
twisted on the trimmer cap it's plenty close enough.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Richard Palmer wrote:
Garey,
I have cleaned my eBay TR-4. Replaced two tubes, V1&V20. Along with
tightening up the ps connector pins and probably some other small forgotten
stuff it seems to be working nicely. Although I still have yet to make
"first contact". I thought I'd go through the complete alignment procedure
to check and adjust as necessary.
( I thought I had a source for two 0.01pF capacitors from Allied but their
web site ordering is worse than crap. I called them and to my disbelief
still more crap. So I'm still looking for some caps to get the 0.005pf for
the alignment procedure.)
That's why I asked about calibrating the calibrator. I don't suspect any
problem... just want to check all the settings.
Richard Palmer
KB8NXO
Garey Barrell wrote:
Richard -
Do you have ANY receiver aside from your TR-4? It doesn't have to have a
BFO or be particularly stable or sensitive.
If all you have is a Broadcast Band table radio, see if you have a
commercial station on an even 100 kHz frequency such as 700, 800, 1200, etc.
It doesn't have to be local, in fact best if it isn't too strong, and the
higher the better. Get it close to the TR-4, and possibly wrap a turn or
two of wire around the calibrator tube, bringing the other end near the
broadcast receiver antenna. Turn on the calibrator and adjust your wire
until the calibrator signal is about the same strength as the BC station,
then adjust the calibrator until the signal is at zero beat. Adjust as
carefully as you can, if the signals are near the same strength you'll
actually be able to hear a slow variation in amplitude when you're within a
few Hz of zero.
This is far from ideal, but BC stations are very accurate. When you
calibrate at 10 MHz, you are comparing the 100th harmonic of the calibrator
to a known frequency, whereas with a broadcast station you're only at the
10th harmonic on a 1 MHz BC station. But plenty close enough for our
purposes.
Better still is if you can borrow a receiver that covers 10 or 15 MHz,
and if you can resist adjusting the calibrator, they stay correct for a LONG
time. In fact, unless someone has been "adjusting" it, it's probably close
enough!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Richard Palmer wrote:
The manual says to tune to WWV ect.ect. I'm assuming this is 10Mc. . Can
I use a signal generator set to 10Mc. and accomplish the same desired
result? I have neither of these and must buy what I need to skin this cat.
Any suggestions? One caveat... it must be inexpensive.
Thanks in advance,
Richard Palmer
KB8NXO
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