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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