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 Of john@kk9a.com
>> Sent: Wednesday, December 6, 2023 9:43 PM
>> To: amps@contesting.com
>> Subject: Re: [Amps] Starting up a NEW Henry amp
>>
>> [You don't often get email from john@kk9a.com. Learn why this is
>> important at https://aka.ms/LearnAboutSenderIdentification ]
>>
>> CAUTION: This email originated outside of the organization. This
>> message might not be safe, use caution in opening it. If in doubt, do
>> not open the attachment nor links in the message.
>>
>> 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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