[Amps] Starting up a NEW Henry amp

[Joe Subich, W4TV]

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 at contesting.com> On Behalf Of john at kk9a.com
>> Sent: Wednesday, December 6, 2023 9:43 PM
>> To: amps at contesting.com
>> Subject: Re: [Amps] Starting up a NEW Henry amp
>>
>> [You don't often get email from john at kk9a.com. Learn why this is 
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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
>>