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Re: Farhan to give sBITX talk at FDIM
That's great news. I can't wait. 73 Owen Vk5fkov On Sun, Apr 11, 2021 at 11:54 PM Evan Hand <elhandjr@...> wrote: I am looking forward to this talk.? I have at least one ?BITX that I plan to convert. |
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Re: Rf it's "freezing" the Ubitx ???
Andrea, I too have had that problem and RF was getting into my UBITX from the key paddle. I used some small diameter coax and a snap on ferrite to solve my issue. Good luck Barry K3bo On Sat, Apr 10, 2021, 10:44 AM Evan Hand <elhandjr@...> wrote:
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Re: Linear Amplifier Build
On 2021-04-11 16:05, John Cunliffe W7ZQ wrote:
They should be easy having a gain of 20db on HF I get that much on 2m Indeed. That's why I always stuck with grounded grid for my tube amps. Much more stable. When I first ordered the uBITX ( impatiently waiting... ) I thought of doing a single-sweep-tube amp for it, or maybe a single 6146B. That was before I found out just how far the solid state stuff had come. - Jerry KF6VB |
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Re: Linear Amplifier Build
do aim for stability and cleanness over raw power - and keep in mind this simple math:
each time you increase power 4X this is 6 dB, and roughly it is one S-unit.? if we start with 10 watts, 40 watts is one S-unit stronger and 160 watts is 2 S-units total -- so don't sweat for every watt.? a small amplifier could help your ubitx - but if you seek out big signals on SSB - the funny thing is many of them can hear you as is.? I remember the central Eu station that scolded me for giving my call twice and we doubled on the second one.? keep learning along the way.? Curt |
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Re: Linear Amplifier Build
Jerry, KF6VB,
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Ooooh, an excellent opportunity for the QRP operator. Stuff a slingshot, a motorcycle battery, some magnet wire, and that new uBitx? into a daypack, head on up that hill.? That sort of thing is even easier now that winter is done. Don't forget the six pack of beer. You earn it doing the hike. Jerry, KE7ER On Sun, Apr 11, 2021 at 10:52 AM, jerry@... wrote: *** It's a 6BTV vertical perched on the side of a hill. I'm pretty sure the hill is the problem. I used to get excellent reports from the south Pacific. |
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Hi Jerry,
There's no compile-time requirements to use the favorites. To set a favorite, tune to the frequency you want to save, then short press the star icon, and finally long press the desired memory slot (on the right of the screen) to save it. To recall, press the star icon, then short press the favorite slot (again on the right) desired. I only programmed 4 slots because that's all that would fit on the screen nicely, however there is plenty more space in the EEPROM if you wanted to modify the code to store more. Reed |
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Re: Linear Amplifier Build
John Cunliffe W7ZQ
They should be easy having a gain of 20db on HF I get that much on 2m from a pair of them.Careful though, with the gain they have you can easy get into feedback situations if you are not careful with the placement, relays, and shielding.
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John On Sun, Apr 11, 2021 at 06:03 PM, jerry@... wrote: On 2021-04-11 12:41, Rafael Diniz wrote: |
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Re: Linear Amplifier Build
I
On 2021-04-11 11:34, Arv Evans wrote: High power amplifiers seems to be the antithesis of where we are*** I apologize for that. Basically, I was excited to be doing ham radio for the first time in many years, and this was the group I was connected to. I'll try to keep the power down :). - Jerry KF6VB |
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G.A.(Jerry) Minor
I assembled a v.6 last night, and installed Reed's firmware. Playing around with it, I cannot make sense out of the favorite frequency function. Do the favorites need to be defined in a sketch prior to compiling? I tried short/long presses trying to transfer the frequency into the selected favorite, and it doesn't appear to work. Also, I am wondering if you are limited to 4 favorite frequencies. I looked at Reed's documentation on Github, but still came up blank. Any help would be appreciated. Thanks.
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Re: Linear Amplifier Build
On 4/11/21 11:59 AM, jerry@... wrote:
There is the Hardrock line of amp kits: and a forum on Google groups: -Dj -- Dj Merrill - N1JOV Currently Flying: Glastar Previously: Cessna 150 - Glasair 1 FT - Grumman AA1B |
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Re: Linear Amplifier Build
On 2021-04-11 12:41, Rafael Diniz wrote:
Hi Jerry,MRF300AN and MRF300BN. They are said to have an in-circuit gain of 20dB. If that's true, then 6W in - gets you 600W out. - Jerry KF6VB I'm using a BLF9120 based kit I bought on aliexpress, it works pretty |
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Re: Linear Amplifier Build
Hi Jerry,
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Which transistors are in the finals of this kit you bought? I'm using a BLF9120 based kit I bought on aliexpress, it works pretty well, but up to 100W at most. Rafael PU2UIT On 4/11/21 12:59 PM, jerry@... wrote:
All, |
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Better heat sinking
I was never overly confident of the two small heat sinks supplied for the IRF 510's. I had made a modification to get rid of the heat on the 5 volt regulator and also steady the vertical board which is slotted into the main board. The rig is a V5 board.
I fitted a copper heat sink that I had left over from a long defunct laptop. I also took the opportunity to fit the 2 back to back diodes to protect Q90, which I had to replace a few months ago. I had to butcher the back of the case (bought on Alibaba) as the power sockets, fuse holder and on/off switch were located there and the new heat sink wouldn't fit with them there. The photos show the rig, and the heat sinks that are fitted. The aluminium strap stabiliser/heat sink was fitted when I first built the rig. The heat sink is at top of photo, the aluminium strap on the left stabilises the vertical board and acts as a heat sink for the 5v reg.The small board on the right is a CW filter from Sotabeams and makes working CW a pleasure. The new copper heat sink from above |
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Re: Linear Amplifier Build
High power amplifiers seems to be the antithesis of where we are going on a mostly QRP based discussion group.? Some may disagree, and they are entitled to do so, but please respect the fact that this is basically a QRP focused group. Arv _._ On Sun, Apr 11, 2021 at 12:29 PM Jerry Gaffke via <jgaffke=[email protected]> wrote: After looking around the web some at anything "amateur linear amplifier", |
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Re: Linear Amplifier Build
After looking around the web some at anything "amateur linear amplifier",
seems to be mostly CB'ers speaking a mostly different language. They seem obsessed with how many "pills" (output transistors) an amp has rather than any meaningful specs. I'd guess that's the crowd many of the ebay amp kits are aimed at. Makes me wonder how many get put on the air without any attempt at an LPF. Here's where I go when I want to daydream about ridiculously powerful transmitters: ? ?? Jerry, KE7ER |
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Re: Linear Amplifier Build
?? _._ On 2021-04-11 09:56, Jerry Gaffke via wrote: |
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Re: Linear Amplifier Build
On 2021-04-11 09:56, Jerry Gaffke via groups.io wrote:
Jerry, KF6VB,Indeed. I'd take another look at that antenna.*** It's a 6BTV vertical perched on the side of a hill. I'm pretty sure the hill is the problem. I used to get excellent reports from the south Pacific. There's a 300-foot coax run from the antenna to the bedroom. It's good stuff - Davis Buryflex RG/8. And yes, some of it is buried :). To minimize coax losses, I have an automatic tuner right under the antenna. Should be a bunch more sunspots coming along soon.*** Sure thing! Actually, it's in the downstairs bedroom/office. Not where we sleep. I wouldn't dare put it up there. - Jerry KF6VB If it's in the bedroom now, I'm guessing sooner rather than later. |
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Re: Linear Amplifier Build
There is one on facebook. I am no longer on facebook so I can't retrieve the page's link.? - f All, |
Dj Merrill
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