Tube rf amp
Lee Blaver
However I have a simple, single stage CB rf linear amp here using
a single PL509 (or EL509). The amp works, but only outputs 6 W for a 4W
input.
How can I verify that the tube is shot? They are somewhat expensive
around here :-)
The filament is ok and I have checked the power supply and caps, there
isn't really much else to it :-)
Lee
Arthur Jernberg
supressor grid, and plate. Check the plate voltage while applying an active
signal to the unit. Open the cathode circuit and install a device to measure
the current being drawen by the valve while in the power mode of operation,
compare that reading to standby current. Is this specific device constructed
is a way to alow plate and grid tuning to set the parametres of the amp
specifically to the applied frequency. Many of these devices tend to be
rather inadequate in power transfer unless they are tuned to the particular
operating frequency. Simplest is to subsitute another valve into the circuit
to confirm preformance.
"Lee Blaver" <lee.b...@btopenworld.com> wrote in message
news:3D970BC7...@btopenworld.com...
Lee Blaver
>Check the available voltages to the valve, esp those to the control grid,
>supressor grid, and plate. Check the plate voltage while applying an active
>signal to the unit. Open the cathode circuit and install a device to measure
>the current being drawen by the valve while in the power mode of operation,
>compare that reading to standby current. Is this specific device constructed
>is a way to alow plate and grid tuning to set the parametres of the amp
>specifically to the applied frequency. Many of these devices tend to be
>rather inadequate in power transfer unless they are tuned to the particular
>operating frequency. Simplest is to subsitute another valve into the circuit
>to confirm preformance.
>"Lee Blaver" <lee.b...@btopenworld.com> wrote in message
>news:3D970BC7...@btopenworld.com...
>
>
This is a really simple design, there is a basic tuning capacitor but
that is it , the circuit for firing the
transmit relay is more complicated than the amp itself :-)
The power transformer is no where near up to the very optimistic 100w
(fm) rated power of the amp either....
I'll measure the voltages and current as you suggest, but it looks like
I'll be ordering a new
tube :-)
Lee
John Todd
<lee.b...@btopenworld.com> wrote:
>This is a really simple design, there is a basic tuning capacitor but
>that is it , the circuit for firing the
>transmit relay is more complicated than the amp itself :-)
>The power transformer is no where near up to the very optimistic 100w
>(fm) rated power of the amp either....
>
>I'll measure the voltages and current as you suggest, but it looks like
>I'll be ordering a new
>tube :-)
>
>Lee
>
Before you blame the tube, make sure its tuned properly.
Vacuum tube finals are picky that way. With no load, tune
the plate tank for minimum current. Connect the antenna and
tune the matching device for max current. Put a neon bulb
near the tank during the last, the max current and max
brightness should occur together. Do all this in short
sessions, monitoring the tube temperature with
your cheek.
--
_______________________________________
John E. Todd <> jt...@island.net
Note: Ensure correct polarity prior to connection.