When doing this, unless this Tuner is placed between the T/R relay and
the tube, it ends up being in the RF path on recv also. Isn't this going
to make a bad load to the recvr of a good antenna?
Joe WB9SBD
On 12/11/2023 1:13 PM, garyschafer@largeriver.net wrote:
Do not use the radios internal auto tuner.
Use an external MANUAL tuner and tune it when running maximum power. If you try
to use the internal auto tuner it will not tune properly as it tunes up at low
power and the input impedance of the amp changes as the power increases.
Check the input SWR when running maximum power/drive.
73
Gary K4FMX
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Carl Braun
Sent: Monday, December 11, 2023 12:10 PM
To: Joe Subich, W4TV<lists@subich.com>;amps@contesting.com
Subject: Re: [Amps] Starting up a NEW Henry amp
Thanks Joe
Any fix or mod for this? If not, I'll continue to use the rigs tuner to knock down the
SWR to ensure I don’t cause any damage to output transistors on the 7800 or
other transceiver.
-----Original Message-----
From: Amps<amps-bounces@contesting.com> On Behalf Of Joe Subich, W4TV
Sent: Monday, December 11, 2023 11:53 AM
To:amps@contesting.com
Subject: Re: [Amps] Starting up a NEW Henry amp
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On 12/11/2023 12:38 PM, Victor Rosenthal wrote:
The Henry Ultra amps have pi-network input circuits for each band.
They have adjustable coils, L1-L6 on the schematic. If someone has
misadjusted them, you can see high SWR.
The 3K/8K Ultra does not have tuned inputs ... it has a pair of
1:1.56 "UNUN" and no (cathode) swamping unlike the Alpha 77 which has a tuned
tank (parallel resonant) per band. The lack of a tuned input in the Henry places the
uncompensated grid to cathode capacitance directly across the input.
The 3K and 8K Ultra manual with schematics and parts list is here:
<http://bama.edebris.com/download/henry/3k8kultra/3K%20and%208K%20Ultra.pdf>
73,
... Joe, W4TV
On 12/11/2023 12:38 PM, Victor Rosenthal wrote:
Carl,
I understand that the SWR as shown on the meter in the transceiver is
high when the amplifier is operating, but the SWR on the line to the
antenna is normal. Is that correct?
The Henry Ultra amps have pi-network input circuits for each band.
They have adjustable coils, L1-L6 on the schematic. If someone has
misadjusted them, you can see high SWR.
Does this happen on all bands or just some of them?
73,Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 11/12/2023 18:08, Carl Braun wrote:
Hello John
I am seeing high VSWR on my 7800 when using the Henry ULTRA amp. I
don't hear or see RFI on my monitored signal but the VSWR meter is
certainly responding differently to the Henry amp than it does to my
Alpha amp. By engaging the tuner on the 7800 I can get MOST of the
Henry's VSWR down to under 1.5 or so. Placing a W2FMI line isolator
(1:1) in between the 7800 and the Henry did nothing to lessen the
high VSWR I saw coming back at the transceiver. It should be noted
that the RF console was approx. 3' from the transceiver at the time
of testing with a 25' RG-58 exciter coa from the rig to the input of
the amp.
I've pulled my dummy load out of storage and am ready to test the amp
with that. The antennas I have been using with the Henry are all
flat at their respective frequencies. I see less than 1.3:1 at 1.5KW
on my Powermaster II monitor, and on the 7800 VSWR meter, when using
the Alpha. Palomar is sending over a couple of choke kits for the
radio room and the antenna feeds. Choke kits for the TXCVR and AMP
as well as 1:1 chokes for vertical antenna feed points. As one
responder noted; Henry basically suggests you don't use the tuner in
the TXCVR to knock down any VSWR. I plan on asking Dennis Pickering
about the issue next time I have him on the phone.
More experimenting later this week as I am currently wiring in a
240VAC feed on the opposite side of the radio room so I don't have to
test the Henry consoles in close proximity of the operating position.
More updates afterward.
Carl W9LF
-----Original Message-----
From: Amps<amps-bounces@contesting.com> On Behalf Ofjohn@kk9a.com
Sent: Wednesday, December 6, 2023 9:43 PM
To:amps@contesting.com
Subject: Re: [Amps] Starting up a NEW Henry amp
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Are you saying that the Henry is causing RFI in your transceiver? Is
this occurring with a dummy load or does you antenna feedline have CMC?
John KK9A
Carl Braun W9LF wrote?
By enabling the tuner in the rig I can knock down most of the SWR
when running the Henry's but I don't have to do that with my other
amp. One difference... I do have a longer coax run (25') from the
Henry's back to the PM II watt meter . The Alpha has a three ft (3')
jumper from the amp to the watt meter. I'm going to shorten the coax
from the Henry RF consoles to the coupler to 8' or so to see if that
lessens any of the RF coming back to the rig. I do have a W2FMI line
isolator in the line going to the amps with no visible changes. More
parts are coming like RFI kits for the amp and transceiver, a 1:1
unun for the output of the amp and one for the base of the antenna.
Any other Suggestions?
Thanks
Carl W9LF
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