|
The LA-1K operates perfectly
well on 30 meters at 200 watts, driven with 7 watts.
Just finished a long CW chat on 10.118.
See pictures.
End of discussion.
73,
Kent
K9ZTV
|
Thanks Kent? K9ZTV:? ? I have avoided using LA1K on CW because its relay(s) just are not designed for such service.? What procedure did you use to avoid premature death of the relay(s)?
Thanks? ? 73? ? James? ?N8TT
------ Original Message ------
Date 6/7/2023 10:00:14 PM
Subject [la1k] 30 METERS
The LA-1K operates perfectly
well on 30 meters at 200 watts, driven with 7 watts.
Just finished a long CW chat on 10.118.
See pictures.
End of discussion.
73,
Kent
K9ZTV
|
Hi James ...
I use the Direct Keying mode in the LA-1K with a DX Connections QSK2500 T/R switch ().
It's an excellent product and turns the LA-1K into a full QSK amp.
73, Kent K9ZTV
toggle quoted message
Show quoted text
On Jun 7, 2023, at 9:47 PM, James <JCM@...> wrote:
?
Thanks Kent? K9ZTV:? ? I have avoided using LA1K on CW because its relay(s) just are not designed for such service.? What procedure did you use to avoid premature death of the relay(s)?
Thanks? ? 73? ? James? ?N8TT
------ Original Message ------
Date 6/7/2023 10:00:14 PM
Subject [la1k] 30 METERS
The LA-1K operates perfectly
well on 30 meters at 200 watts, driven with 7 watts.
Just finished a long CW chat on 10.118.
See pictures.
End of discussion.
73,
Kent
K9ZTV
|
The QSK-2500 seems to be a decent QSK solution if you must have it for a $395 price. I'm fine with semi-break-in. I assume the LA-1K works fine with semi-break-in using appropriate delay set on the transceiver to control excessive relay clicking, correct?
30m Band: I read the explanatory note about 30m in the LA-1K manual on Palstar's website. It still seems counter-intuitive to select [20-15] when you want to use the 30m band. That might make sense for 17m but not 30m in my opinion. It seems that the LA-1K was not really designed with 30m in mind. The manual comments that with a 200W limit the amp is normally not required. I don't quite understand that logic when so many other amplifiers have separate band selections for all bands 160-6m including all WARC bands. What is the purpose of grouping bands (20-15 and 12/10)? This could be a problem for me, since I use DXLabs to send frequency data to the HF-AUTO via the HF-AUTO SW app which works well and my ACOM amp reads the same data and sets the band accordingly. All this happens before any RF is applied. I'd really like to get the LA-1K but given its design, I'm not sure how well it would play in my setup.
--
73, Norm/KC1BMD
|
Hi Norm,
Semi break-in works fine in Direct Mode. ln Normal Mode with semi break-in, the relays "always" hot switch on the first dit or dah of EACH transmission. In CW mode in contrast with SSB mode, "max" RF output power is applied immediately at the start time of each transmission when the relays are hot switching. There is no way around it in Normal Mode. SSB outputs less power at the start of each transmission making it a little safer.
l recommend using Direct Mode for "all" CW with any "auto band-switching" amp. It only makes sense!
73
.... Bill K3HZP
DX Connection
|
On Thu, Jun 8, 2023 at 12:45 PM, Norm - KC1BMD wrote:
What is the purpose of grouping bands (20-15 and 12/10)?
Hi Norm, Great question; I have seen vintage RF amplifiers with inferior design implementation such as grouping bands (my bad; could be state-of-the-art design back then) that's acceptable in my Ameritron ALS-600 (see attached pic) for having only one RF output.? You might want to see my post /g/la1k/message/1282 where I described an obscure antenna assignment limitation found in the LA-1K due to grouping 20M-15M as one band-select choice.? Said limitation is a showstopper for hams that want to operate on those bands with a 20M monobander connected to Ant 1 and a 15M monobander connected to Ant 2, as an example.In terms of the 30M band situation, you will want to check out my post /g/la1k/message/1311 for my observations and rhetorical questions.? You will also want to check out my post /g/la1k/message/1328 where I have attached a copy of the original LA-1K Technical Manual, as submitted to the FCC by Palstar in 2017, for all to consider.? I will leave it to you to draw your own conclusions. 73, Ray KJ5MI
|
On Thu, Jun 8, 2023 at 02:26 PM, Bill K3HZP wrote:
ln Normal Mode with semi break-in, the relays "always" hot switch on the first dit or dah of EACH transmission.
I'm possibly misunderstanding the timing diagram in the LA-1K manual. It would seem that low power drive is applied but the output relay is closed (and ready to pass high power) before the input relay is closed which would apply the drive power to the amp PAs. So, I'm not sure how it is being hot switched. About direct mode: I would prefer that but I think I would need the LA-1K to be able to read frequency data from either the HF-AUTO, or from DXLab Commander as it is set up now. Otherwise, I would need a special cable from my iCOM rigs to the amp (and I have three ICOM rigs). It is much more flexible to be able to read frequency data at the amp from any radio through a rig control program such as DXLab Commander than to have to use radio-specific cables which would have to be switched to the amp when rigs are changed. ? -- 73, Norm/KC1BMD
|
Hi Norm,
The problem in CW Normal Mode is that the initial applied power is full power, NOT reduced power on the first dit or dah of each transmission. This is not tune mode; this is actual CW sending in a conversation. Since the first dit or dah is applied at full power, the power has to go somewhere. The LA1-K needs 20 ms to make a decision and select the band (at this input power!). At full transceiver output power, the amp relays now close. The relays must be hot-switched since the transceiver is at full output power during their closure. Note that the first dit or dah is always shortened by 20 ms! (High speed CW OPs, i.e. CWT OPs, be aware of the shortening!!)
In Direct Mode, the amp goes into transmit immediately when the transceiver outputs the amp key signal to it. This key signal is 10 ms to 15 ms BEFORE RF arrives at the amp. The relays are settled by the time RF arrives at the amp, and no hot switching occurs.
As for the cables, I am not the expert. Possibly Kent K9ZTV or someone else can help with those.
GL
.... Bill K3HZP
|
On Thu, 08 Jun 2023 13:26:38 -0700, Ray KJ5MI wrote:
Great question; I have seen vintage RF amplifiers with inferior design implementation such as grouping bands (my bad; could be state-of-the-art design back then) that's acceptable in my Ameritron ALS-600 (see attached pic) for having only one RF output.? You might want to see my post /g/la1k/message/1282 where I described an obscure antenna assignment limitation found in the LA-1K due to grouping *20M-15M* as one band-select choice. *Said limitation is a showstopper for hams that want to operate on those bands with a 20M monobander connected to Ant 1 and a 15M monobander connected to Ant 2, as an example.*
Selectable outputs is a feature found in today's solid-state amplifiers. In years gone by antenna switching was done manually. Amplifiers with tuned input circuits are another relatively new feature. There are 11 amateur bands between 160M and 6M inclusive. Using the given example how many amplifier outputs are needed to have a truly unflawed design? If there are multiple antennas selectable for a single band, would that be an amplifier design flaw? When someone purchases an amplifier which doesn't suit their needs it's not an amplifier design flaw. It quite simply a poor buying decision resulting from poor pre-purchase research. All the corner-case examples in the world cannot change that fact. 73 de n4jvp Fritz
|
On Jun 8, 2023, at 7:36 PM, A.G. von Luternow <n4jvp@...> wrote:
?On Thu, 08 Jun 2023 13:26:38 -0700, Ray KJ5MI wrote:
Great question; I have seen vintage RF amplifiers with inferior design implementation such as grouping bands (my bad; could be state-of-the-art design back then) that's acceptable in my Ameritron ALS-600 (see attached pic) for having only one RF output. You might want to see my post /g/la1k/message/1282 where I described an obscure antenna assignment limitation found in the LA-1K due to grouping *20M-15M* as one band-select choice. *Said limitation is a showstopper for hams that want to operate on those bands with a 20M monobander connected to Ant 1 and a 15M monobander connected to Ant 2, as an example.*
Selectable outputs is a feature found in today's solid-state
amplifiers. In years gone by antenna switching was done manually.
Amplifiers with tuned input circuits are another relatively new
feature.
There are 11 amateur bands between 160M and 6M inclusive. Using the
given example how many amplifier outputs are needed to have a truly
unflawed design? If there are multiple antennas selectable for a
single band, would that be an amplifier design flaw?
When someone purchases an amplifier which doesn't suit their needs
it's not an amplifier design flaw. It quite simply a poor buying
decision resulting from poor pre-purchase research. All the
corner-case examples in the world cannot change that fact.
73 de n4jvp
Fritz
|
On Thu, Jun 8, 2023 at 07:36 PM, A.G. von Luternow wrote:
When someone purchases an amplifier which doesn't suit their needs
it's not an amplifier design flaw. It quite simply a poor buying
decision resulting from poor pre-purchase research. All the
corner-case examples in the world cannot change that fact.
My earlier post here /g/la1k/message/1285 pointed out "Btw, I had a telephone conversation with Mark Ward (Palstar technician) on their inferior design implementation in grouping 20M-15M as one band-select choice, shortly after I received my LA-1K.? Mr. Ward thought at the time surely the LA-1K would allow a 20M monobander on Ant 1 and a 15M monobander on Ant 2, if I wasn't using RF sensing.? So Mark tried doing it without RF sensing and was unsuccessful in making the LA-1K to permit a 20M monobander on Ant 1 and a 15M monobander on Ant 2.? Case closed!" Mark Ward is a longtime Palstar employee with whom I had a telephone conversation lasting about twenty (20) minutes going over anything that I might have missed relying on publicly available LA-1K information (e.g. Palstar.com, eHam.net) before I placed my LA-1K order.? Mr. Ward told me that he was employed by Palstar at the time the company introduced the LA-1K. in hindsight, maybe I should have a pre-purchase conversation with members of their LA-1K design team to go over their internal detailed design requirement documents so one can determine with any degree of certainty what would be regarded as a design flaw.? But then again, no telling if any of those original LA-1K design engineers chose to remain with the company during the COVID-19 pandemic. 73, Ray KJ5MI
|
On Thu, Jun 8, 2023 at 06:59 PM, Bill K3HZP wrote:
The problem in CW Normal Mode is that the initial applied power is full power, NOT reduced power on the first dit or dah of each transmission.
Thanks for the explanation Bill. I was thinking that hot switching would be more of a problem with amplifier output being applied before the output relay is switched. What you describe is radio drive power (much lower) being applied before the input relay is switched. I guess that is technically hot switching but is it that serious (ie. is the input relay being over-stressed switching with what, maybe 10-40W drive,... just a rough average)? Now, the 20ms delay on the first dit could be a problem. But what then is the purpose of the design that incorporates "normal keying" mode with these two serious problems? ? -- 73, Norm/KC1BMD
|
Norm ...
Two things to keep in mind:
(1) DIRECT mode requires a band-data cable from the transceiver to either the "Radio Interface" jack or the "RS-232 Band Control" jack. Without a band-data cable, the amp reverts to NORMAL Keying mode.
(2) In the LA-1K, 30 meters is not a separate band. When the transceiver calls for 30 meters, (either through RF sensing or band-data cabling), "20-15" is indicated on the screen. There is a note about this on page 12 of the online manual under the headline, "External Data Connectors."
Moreover, at first I was troubled by the third sentence in that note which seems to imply that Direct Keying is not possible on 30 meters. But closer reading indicates this restriction pertains only to Icom transceivers and not to Yaesu, Elecraft, or Kenwood transceivers. Since you own an Icom, I'd recommend consulting Paul or Mark at Palstar for further clarification.
Finally, while the last sentence in this note stating amplifier operation is not normally used on 30 meters is probably true, neither does it mean 200 watt operation on 30 meters is precluded. I have many 30 meter DX contacts in my log using the LA-1K.
73,
Kent
K9ZTV
|
Norm,
Auto band selection is a very good sales pitch!
I do not like shortening the first dit or dah of each transmission. I do not know how much hot switching shortens a relay's life? I "assume" that the antenna relay and input relay are correctly sequenced so that the antenna relay closes first and then the input relay closes. This prevents hot switching of the amp output power. As an EE, I would not design an amp this way for CW, although many people appear to be happy with it.
73
.... Bill K3HZP
|
As another EE, I guess I would have to agree! If Palstar ever decides to redesign the LA-1K, or design a new amp, with CAT control to read frequency/band data (e.g. via USB from rig control programs or possibly their HF-AUTO), I would be quite interested in that product.
--
73, Norm/KC1BMD
|
Norm - KC1BMD
Bill K3HZP
