True for casual operating but when chasing rare DX every dB counts! :D
73
-Jim
NU0C
On Fri, 08 Mar 2024 11:22:13 -0800
"amfone via groups.io" <amfone20000@...> wrote:
True Rick the Drake gear used carrier control output in the AM mode ( no agc when using AM ) and the amp really? thinks its looking at an SSB signal. I've done this too with? good reports. And yes on the db difference you noted, at 100watts you have to get to 200 watts to just get 3db of signal difference on the receive end and to 400 watts to get an S-Unit.
73 Tim
WB8UHZ
On Friday, March 8, 2024 at 02:12:38 PM EST, Rick W4XA <myr748@...> wrote:
On Tue, Mar 5, 2024 at 11:21 AM, amfone wrote:
//////I normally tune for about 500 watts on the meter, this is below of course the ratings for the tube noted by Drake in the manual. If I run AM phone with the amp using a modern rig I will have a carrier output of not more that 125 watts,///////73 and thanks again.?Tim?WB8UHZ???
Tim,
You mentioned running AM with the L-4B and I thought I would share my experience running AM with my? C-Line.?? I think just about everyone here know that Drake used screen modulation with carrier control in the TR-3/4/6 transceivers and the T-4x A/B and maybe others.
It's interesting how really inefficient it is (using Drake tube transceivers and transmitters)? considering (IIRC) that they either screen modulated the driver (12BY7... TR-4/T-4X) or the final 12JB6's in the TR-3 etc.
So using an L-4B (or L-7) driving with a T-4X or TR-4 you could conceivably be running a screen modulated AM signal through 2 linear amplifiers (2 or 3 6JB6)? or just the 12JB6's in the TR-3
But it would appear that Drake intended the L-4/L-4B on AM to be operated using a Drake "driver" which would loosely approximate the average and peak power of driving with SSB.
And so I have actually used my T-4XB (that I bought new) to drive the L-4B on AM. (In the SSB MODE)
All tuned up, the "resting" carrier (controlled)? level is not quite 150W.?
Running the amp on 240 AC, It "talks" up to around 1400W PEP (output)? measured with both the? Array Solutions Power Master II and the peak reading watt-meter in the Palstar HF-Auto tuner.
I get signal reports similar to what the Viking 500 guys get in the Pacific NW
Driving it with any other NON-carrier controlled AM driver would require up to 375W of "resting" (or steady ) carrier to even come close to the above PEP
The 3-500's do also show some "color" when operating on AM.? I also tried a pair of 3-400's (that I have for my Loudenboomer) and they produced identical results.
Now having said all that, I never do "Lock-to-Talk" AM for 20min or even 10min like some of my "Verbose" friends do!? In fact, when I pause, I drop the carrier.?
But if I stop talking the power output still drops to a little less than 150W
I don't think anyone has ever told me that they could tell I was using Carrier Controlled AM unless I mentioned it.
And I actually would rather use my Viking Valiant anyway.?
Besides, 450W PEP with the Valiant and the 1300-1400W PEP running the C-Line / L-4B is only about a 5db difference and not really worth it.
73/Rick
W4XA
*Every post is created using Linux
--
73
-Jim
NU0C
Jim Shorney