Curt -
This just means that the 'low band' VCO is unlocked. The 'low band' VCO
covers 14 MHz and down. You should read about 17 MHz rather than 12,
which is probably why it's losing lock. If you switch to any of the
'high' bands (21 and up) and depress the FIXED - RCV button you should
see ~32 MHz, and any of the 'low' bands (14 and down) should be ~17
MHz. Of course both are 'wandering' frequencies as this is the VCO's
running 'unlocked'.
One common problem that can cause this is a loose or missing core top
half on the DC-DC converter transformer on the power supply board just
behind the GAIN and DELAY adjustments. The transformer core consists of
two halves, each 'E' shaped, super-glued together, 'facing' each other.
If the top half becomes loose or even falls off, the +25V supply drops
considerably. So if you look at the transformer on the board, you
should see a solid bar across the top. If you see three square legs
sticking up, check the bottom cover for the transformer core top! If
you see the 'bar', make sure it's tight to the other half. You may
touch it and have it fall off. A few drops of super glue will fix it.
If this is NOT the problem, check the +25 VDC bus. If it's good, then
something has changed the VCO 'unlocked' frequency and you'll need the
service manual information to find out if it's an adjustment problem, or
some other failure.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Curt Nixon wrote:
GM All:
Hope you all are keeping warm. 10F here and all antennas iced up.
Have a problem that just started over the weekend with the TR7 here.
All works fine except when I try to select 14MHz. the display goes to
12xxxx MHz.
If I start at 21 and step down with the 500K dwn button, it goes to
14500 and then the next step goes to 12000 stepping back up 14 comes
back on.
I havent checked yet to see if it is actually running on 14 but
displaying 12 but it is stable there...not flickering or anything.
Common problem?
Boards have not been re-seated in a while but rig has not been stored.
Use this rig nearly every day. and it has been running great.
Curt
KU8L
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