[Drake] Questions from new a ham (long)
Jeff Anderson
Jeff Anderson" <[email protected]
Wed, 11 Sep 2002 12:09:36 -0600
I'm looking for some information on basic transmitter operation. I am
posting these questions here because I would like input from people that
understand the tuning of tube finals, and manual antenna tuners.
I have had my license for nearly a year, but have yet to get on the air and
actually speak to anyone. I have worked on tube receivers for many years
(beginning with R-390s while in the Navy), but have no experience with
transmitters.
My station consists of a TR-3 (a hamfest unit that required lots of work)
with a D-104 mic, an L network tuner that I built (has no tuning indicator),
and a G5RV antenna that I recently put up. I also have an MFJ 259B antenna
analyzer, the W-4 watt meter, and some no-name inline SWR meter that I can
use to help me get things set up.
Most of my questions involve technique for proper matching of the
transmitter to the antenna.
1. Must the antenna be accurately tuned before tune-up of the TR-3 is
attempted?
2. Will the tuning of the antenna effect the tuning of the transmitter?
Using the MFJ analyzer, at the point where the feedline connects to the
TR-3, I have verified that the tuner will match the antenna with an SWR of
less than 2:1 on all bands.
3. Is the use of an inline SWR meter the proper method to ensure proper
antenna tuner adjustment in a normal station setup?
4. The W-4 watt meter will display forward and reverse power, but it seems
to require the use of a lot of forward power to get usable meter movement
when viewing reverse power. Is this not the proper device for antenna tuner
adjustment?
5. Is there any way to verify proper adjustment of the antenna tuner using
the plate current meter on the TR-3?
With regard to TR-3 tune up, the thing I have the most concern about is:
6. How fragile are the final tubes????
The manual states not to allow more than .1 amps of plate current for more
than 30 seconds or so, or the finals could be damaged. Is this due to the
high SWR that could be present during tune up? I don't want to damage the
finals (they did cost a lot), but 30 seconds isn't very long to tweak all
the knobs that need to be tweaked.
The TR-3 tune-up procedure calls for dipping the plate current, and
maintaining the dip while adjusting the LOAD control.
7. What does it mean if I can't find the dip in the plate current, or if
the dip seems to be all the way to one end of the PLATE control range?
8. Do the proper adjustments of the PLATE and LOAD controls correspond to a
peak power out indication on the W-4 watt meter?
After all this, it seems quite easy to get LOTS of output power (as
displayed on the W-4 watt meter) while performing the tune-up in X-CW mode
as specified. But after tune-up is complete, and the function switch is
returned to the SSB position, the watt meter displays very little output,
the plate current meter moves very little, and the S meter doesn't move at
all when speaking into the microphone.
If the XMTR GAIN control is increased, I can get higher output indications
while in SSB mode, and get the s-meter to move. I believe that this
indicates that the transmit AGC is working, and that XMTR GAIN is adjusted
for maximum output. The output meter still doesn't indicate very much while
set to operate SSB.
9. If the plate current meter displays reasonable plate current while in
the X-CW mode, is this an indication of proper operation of the finals?
What are the indications of weak finals?
Well, thanks for reading this far. I will appreciate any help you can give
me. I would like to make my first QSO some time in the not too distant
future. If I can gain confidence that my station is configured and
operating properly, I should be on the air soon.
It would probably be better to reply off the list. The fewer times this
novel travels around the world, the better.
73,
Jeff Anderson KD7PAW