Although I strictly follow the tuning procedure described in section B on p.
14 in the instruction manual, my T4XB has suddenly changed behavoiur. The
output power on all bands has gone down from on average of 100 watts to 45
watts. The AC-4 bias reads .07 on the plate meter when the gain is
Peter,
Can you test into a dummy load, and if so what are your results? Preferably
with all existing switches, coax, etc out of the path between rig and dummy
load. Just trying to isolate between coax, switch, antenna system issues and
rig issue first.
On the surface it sounds like a rig
Lee -
That sounds about right for the T-4XC Remember, this IS AM! About 20W output is typical, you
only want about 150 mA on voice _peaks_, or about 50W out.
You can swap out V7, and check the value of R63, but it doesn't sound out of line. Of course it HAS
been about 35 years since
Lee -
Last resort, I READ THE MANUAL!! :-)
The L-4B manual says that the drive should be adjusted for approximately 500W INPUT to the L-4B with
no modulation.
Now That was written when transmitter power was regulated by INPUT power, and would
theoretically result in 2000W INPUT of AM
Lee -
I'll never learn... The '500W input carrier' level for the L-4B is for an AM input, i.e. full
carrier.
I still think that 15-20W input to the amp for about 150 to 200W output carrier
is about right.
I'll be quiet now and wait for someone who knows what they are talking
Garey,
Appreciate the help
It was late last night when I checked in with the really nice group of
guys on 3904...so today,
I will carefulley re-evaluate the whole thing and post again.
But, I do remember for sure 350 MA of plate current in AM on the L-4B
with NO input from the Mic.
And I
Years back I ran a C-Line with a Ameritron AL-80 ( single 3-500Z ) which
resulted in a 100 watt carrier. The amps grid current peaks where kept in the
200 ma range.
73, Gary___
Drakelist mailing list
Drakelist@zerobeat.net
Peter -
A sudden change strongly suggests failure of a component.
Your idle current at 70 mA suggests that something before the finals is off and
that the finals are probably okay. Do you get the same output regardless of
whether you use the receiver or the transmitter to control the
I now have my R4A back ,thanks to Lees Kc9cdt, fine work its doing a great
job. Now the T4X, Rebuilt the supply AC-4 ,heath kit board, came out fine.
Fired up the T4x today,set the bias current then followed the tune up procedure
,function switch to TUNE, advanced the gain to .15 amps , turned
Dale,
Are you getting any drive? All bands?
Preselector makes a peak?
Try diffent bands?
Can you hear the signal in a close by rcvr?
If so...does the plate tune make a diffence in the signal level?
All the tubes correct? and all glowing?
Move the band switch all the way through all bands 20
With an A Line, I'd check to see if the problem is on all bands first. The
rotary switch contacts seem to more susceptible on the A-Line for some
reason (silver-plated?). If you're getting full output on some bands and
not on others, I'd check the switch contacts.
Steve Wedge, W1ES/4
Peter -
I also forget to state what 'everyone knows', which is that the first thing is to go through with a
screwdriver and tighten all grounding hardware. The mounting FEET of the small boards are almost
all ground connections.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A,
What suggestions does the group have on re-whitening the lines on the
pointer knobs? I was thinking of using model enamel and a toothpick, wiping
away any excess with qtips. Mike.
___
Drakelist mailing list
Drakelist@zerobeat.net
I use a whitening stick avaiable, I believe, from Antique Electronic Supply.
You make sure the knob is clean, including the white line area, then you rub
the stick over the indentation, wipe off the excess, and there you are!
-Original Message-
From: m coffey r79b...@gmail.com
To:
Hi,
I use water bsed artist's acrylic paint to fill the engraved lettering
on panels, or groove on knobs/ I use a flexible thin pc of neoprene or
similar as a squeegee. The paint is about the consistency of ketchup.
Wipe with a fairly hard, damp, cloth after it's dried a short time, not
On Sun, 5 Feb 2012 19:40:57 -0500, m coffey wrote:
What suggestions does the group have on re-whitening the lines on the
pointer knobs? I was thinking of using model enamel and a toothpick, wiping
away any excess with qtips. Mike.
I've used almost exactly that methid with all kinds of knobs and
What suggestions does the group have on re-whitening the lines on the
pointer knobs? I was thinking of using model enamel and a toothpick, wiping
away any excess with qtips. Mike.
I've been using Liquid Paper white out in a ball-point pen package. You
squeeze the body of the pen as you roll
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