Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- BITX20
- Messages
Search
|
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.
|
|
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 |
|
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 |
|
Re: Linear Amplifier Build
Hi Jerry,
toggle quoted message
Show quoted text
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, |
|
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 |
|
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", |
|
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 |
|
Re: Linear Amplifier Build
?? _._ On 2021-04-11 09:56, Jerry Gaffke via wrote: |
|
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. |
|
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, |
|
Re: Many uBitx's have reduced power on 40m CW
On Sun, Apr 11, 2021 at 10:49 AM, Jerry Gaffke wrote:
Would be useful to know a bit more about how you conducted the IMD test:700 and 1900 hertz were injected into the mic jack.? I had adjusted the level for the maximum power without causing an increase in the IMD3 measurement. ? Exactly which unwanted product was observed when measuring IMDI measured the expected 2xfa +/- fb.? 4 values that were all fairly equal. ? Signal level observed into Q90.I did not probe with the scope. ? Power out to the dummy load.Power out varied from 10 on 80meters to 2 on 10meters Just figures for 40m would be most helpful.Will do it later this week. 73 Evan AC9TU |
|
Re: Linear Amplifier Build
Jerry, KF6VB,
There might well be better forums to complain that 100W is not enough.? ;-) I'd take another look at that antenna. Should be a bunch more sunspots coming along soon. Let me know when the XYL finally convinces you to put that 30L-1 out on the sidewalk. If it's in the bedroom now, I'm guessing sooner rather than later. Jerry, KE7ER |
|
Re: SI labs generator chip which has an FM input pin
John Cunliffe W7ZQ
Why not use phase modulation instead pure FM? The receiver doesn't know the difference and a simple phase modulator stage could be fitted after the clock output, I recall using a germanium transistor and later a FET and coupling the signal from drain and source, balancing it and then unbalancing the whole circuit by having a capacitance diode in one leg that was modulated by the audio. That was in late 60's. early 70s, and my recollection to the details might suffer a little. I bet the circuit can be found and adopted from old books.
John |
|
Linear Amplifier Build
All,
toggle quoted message
Show quoted text
I know this isn't the right forum for this - anybody know of a forum for people building linear amps? Last night, I had my first contact in some years. A pleasant gentleman in Calgary. Unfortunately, he could not hear me as well as I heard him, and we had to cut it short. So frustrating! I was reminded of why we have linear amps. I was running barefoot, 100W. So this morning, I hauled the 30L-1 out of the shed. Oh my aching back! The 30L-1 is a 60's vintage Collins linear with 4 811-A tubes. It's big. It's heavy. It does Not Belong in this bedroom. I'm looking forward to building the LDMOS amp that I ordered on Ebay. Also looking forward to the uBITX transceiver. For me, ham radio is about two things - building equipment, and chatting about building equipment :). - Jerry KF6VB On 2021-04-11 07:50, Evan Hand wrote:
Jerry, |
|
Re: Many uBitx's have reduced power on 40m CW
Evan, On Sun, Apr 11, 2021 at 07:50 AM, Evan Hand wrote:
I did do the testing of my modified v4 against my unmodified v5.? I have posted the power levels of the v4 on this thread.? The IMD measurements that I got are as follows: |
|
Re: Many uBitx's have reduced power on 40m CW
Jerry,
I did do the testing of my modified v4 against my unmodified v5.? I have posted the power levels of the v4 on this thread.? The IMD measurements that I got are as follows: Modified v4: 80meters: -21db 40meters: -19db 20meters: -20db Unmodified v5: 80meters: -22db 40meters: -21db 20meters: -19db As far as I can tell there is not really much difference in the SSB performance with the change of C81 to 2670pF. The only comment that I would make is that overall the IMD3 performance is not what I would like.? Another 5 to 6 dB would have been better.?? Harmonics were down 51db for both rigs.? I did not test for the spur on the v4. Harmonic tests were done with a TinySA connected through a homebrew 50db tap and a step attenuator. IMD3 tests were done with an RSP1A and the RSP-Spectrum Analyzer program using the same connections. At this point, I do not plan to modify my v6 as CW is not a mode I use.? Also, I have other rigs that excel at QRP CW that I would use instead.? So my conclusion is to make the mod IF you want the CW capability.? It does not make sense if you are using SSB. 73 Evan AC9TU |
|
Re: Farhan to give sBITX talk at FDIM
I am really looking forward to this talk. It is the summary of almost a year's experiments in SDR starting from zero. I also describe how to convert a standard issue ubitx into an?sdr using a raspberry pi. - f On Sun, Apr 11, 2021 at 5:29 PM Bob Benedict, KD8CGH <rkayakr@...> wrote:
|
|
Relay computers
farhan@...> wrote:
*** In a former life, I was responsible for repair & maintenance of something called the "Omni 2000". It was an elaborate rack wiring tester. Given a prewired equipment rack, this thing would test it to see that everything was connected to what it was supposed to be connected to, AND that nothing was connected to anything it was NOT supposed to be connected to.My embarrassment would be the relay-based computer science fair This thing had 7000 reed relays. Almost every day, I would have to replace one or more of them. Generally, one would be stuck closed. But opens were common also. I still remember the sound of the Omni's self test. Those relays would whizz in a musical crescendo. It was a union shop. By investing in elaborate test jigs like the Omni, the company was able to use "testers" instead of "technicians" to do the testing. Testers didn't make as much $$ as technicians. The lady who ran the Omni would always say "But Jerry, it worked just this morning!". My answer: "Hazel, everything works until it stops working" :). - Jerry KF6VB |
Dj Merrill
Bob Benedict, KD8CGH
to navigate to use esc to dismiss