|
Hey guys,? I'm looking to get some 2N2222A transistors for my uBITX mods.? Does the following appear a trustworthy source?
2N2222A - Bipolar (BJT) Single Transistor, NPN, 40 V, 300 MHz, 1.2 W, 800 mA, 100 hFE (Pack of 50) (2N2222A)
Otherwise,? I was planning on the $2 each ones from Central at Mouser.?
|
Hi Rob
If they come from China, don't bother. I went this same thing last spring and they were all duds. You're better off getting them from a reliable source.
73
Ken VA3ABN
On Fri, Jan 31, 2020 at 3:10 PM Rob French (KC4UPR) < robert@...> wrote: Hey guys,? I'm looking to get some 2N2222A transistors for my uBITX mods.? Does the following appear a trustworthy source?
2N2222A - Bipolar (BJT) Single Transistor, NPN, 40 V, 300 MHz, 1.2 W, 800 mA, 100 hFE (Pack of 50) (2N2222A)
Otherwise,? I was planning on the $2 each ones from Central at Mouser.?
|
Rather than swap the 6 predriver and drivers with them, go for three of these & a spare -?.? Better output, especially upstairs on 20 meters and up. You only need one 2N5109 for each position that would have taken two 2N2222's.?
Of course you'll still need to add a parallel 20-ohm resistor to each emitter bias resistor to see the full benefit.
- Ted
|
.....but if you really want 2N2222's, these seemed OK when I bought some a while back -
|
Hey Ted,? I'll check the link out... I guess I was skeptical right off the bat for anything from eBay.? I'll take your recommendation ;-).
As I mentioned in the other post, for the resistor I think I will just try to use the unused resistor in each pair as the additional resistor, i.e. since each pair of 2N3904's gets replaced by a single 2N5109.??
If I don't burn one up, I'll use the spare to make that wideband RF preamp you mentioned; looking at the kit from kitsandparts.com, I think I've got everything on hand except the transistor, so might as well just wire it up dead-bug style.
And you didn't change Q90, correct? Left it as a 2N3904, not a BFR106.
|
Doh, looks like the 2N5109s are out of stock.
Which 2N2222's were you referring to???
|
$2 each yikes!? for what improvement?? if you really want them, ask around your local ham club or visit a hamfest (or in the UK they call them Rallys I am told).?
kitsandparts.com (W8DIZ) is a reputable source - but don't see what you are looking for there now.? [and a few folk may be killing off some of the population preparing for FDIM no-smoke competition again]
Isn't the power roll-off in the uBITX a feature - since we tend to need more power at lower frequencies?? okay a healthy 10 watts at 28 MHz may be appreciated - but perhaps better solution is a new rig, if you really want that.? (maybe your track record of uBITX mods is much better than mine - so you need something new to do?? my last bug-a-boo was learning that a relay can go astray - while taking a little while to figure out it was the cause]
I don't know those little SMT 3904's look kind of cute!? have you already replaced the 45 MHz Tx amplifier devices with those high Ft critters?? seems like a more useful effort to me for a v3-v4.?
73 Curt
|
Hey Curt,
I've got a V5.
Which device(s) in the Tx amplifier chain were you referring to?? I have not replaced any amps at all, this is my first "on-board" mod to the uBITX (I have previously installed the kit-projects AGC and BCI filter).? I see in the V5 bidi amplifiers there are BFR93W's, versus 2N3904 in the V4, so I'm guessing maybe the last thing you were referring to is moot.
In truth, I haven't actually measured my V5 output yet (waiting on my watt/SWR/antenna tuner) so I probably shouldn't go changing anything quite yet regardless.? But I definitely want to make sure I'm getting good power out at least down thru 20 meters--I'm using an attic antenna, would like to get whatever oomf out of the radio I can!
Rob KC4UPR
|
Hmmm, Well these are the CW power measurements for my ver3:?
| 2019.02.10 |
| Power measurements on as-delivered uBITX. |
| Supply: 13.8VDC, Current: 0.17A on RX |
| ? |
| Band |
Freq, kHz |
Vrms |
A |
W |
| 75/80 |
3500 |
22.9 |
1.81 |
10.5 |
| 75/80 |
3750 |
25.1 |
2.04 |
12.6 |
| 75/80 |
4000 |
26.9 |
2.4 |
14.5 |
| 40 |
7000* |
- |
- |
- |
| 40 |
7001 |
20.4 |
1.69 |
8.3 |
| 40 |
7150 |
20.6 |
1.76 |
8.5 |
| 40 |
7300 |
20.9 |
1.82 |
8.7 |
| 30 |
10100 |
15.1 |
1.3 |
4.6 |
| 30 |
10150 |
14.8 |
1.28 |
4.4 |
| 20 |
14000 |
16.6 |
1.63 |
5.5 |
| 20 |
14175 |
16.5 |
1.66 |
5.4 |
| 20 |
14350 |
16.4 |
1.68 |
5.4 |
| 15 |
21000 |
7.54 |
1.06 |
1.1 |
| 15 |
21225 |
9.7 |
1.06 |
1.9 |
| 15 |
21450 |
9.62 |
1.07 |
1.9 |
| 10 |
28000 |
7.5 |
1.05 |
1.1 |
| 10 |
28850 |
7 |
0.88 |
1.0 |
| 10 |
29700 |
5.8 |
0.81 |
0.7 |
I haven't done any mods, but the rig certainly could use some help where ever it could be found I think.? Anyway, I don't think $10 or so is too much to spend for some improvement.? How much in total have some here spent on their bitx projects?? I'm sure some have spent many hundreds of dollars judging by the number of ubitx's and accessory kits purchased...
73,
Mark.
|
On Fri, Jan 31, 2020 at 02:10 PM, Rob French (KC4UPR) wrote:
I'm looking to get some 2N2222A
Have you looked at Tayda? https://www.taydaelectronics.com/t-transistors/2n-series/2n2222a-2n2222-npn-transistor-0-8a-40v-to-18.html ? --
|
Hey, Bob,
I'll have to double-check on the BFR106 and make sure I put it in the radio i think it went to.
Sorry the 2N5109's didn't pan out; I guess that was a deal.? Here are some 2N2222's I've used which were just fine -???
If you want the radio to be more happy on 20, try the 2N2222's with an additional 20-ohm on Each emitter bias resistor -?? Then get a step-up buck converter??to feed around 20 volts to the finals;? feed the rest of the radio 14 volts.? ?It's not quite as hot as with the 2N5109's in by experience to date, but it's worth doing.?
See the 5109's nesting in their natural habitat.
Ted K3RTA
On Fri, Jan 31, 2020 at 16:28, Rob French (KC4UPR) <robert@...> wrote: Hey Curt,
I've got a V5.
Which device(s) in the Tx amplifier chain were you referring to?? I have not replaced any amps at all, this is my first "on-board" mod to the uBITX (I have previously installed the kit-projects AGC and BCI filter).? I see in the V5 bidi amplifiers there are BFR93W's, versus 2N3904 in the V4, so I'm guessing maybe the last thing you were referring to is moot.
In truth, I haven't actually measured my V5 output yet (waiting on my watt/SWR/antenna tuner) so I probably shouldn't go changing anything quite yet regardless.? But I definitely want to make sure I'm getting good power out at least down thru 20 meters--I'm using an attic antenna, would like to get whatever oomf out of the radio I can!
Rob KC4UPR
|
Rob
Yes I was thinking those bfr93 that you already have. Most of the v4 our club has built typically have around 10 watts on 80m dipping to 4 watts on 10m. Mine is actually stronger on 20m than 40m. See what yours is doing of course, and its a lot of work to level this out. The bfr93 is mostly to improve transmit ssb spurious more than output power.
Mark
I was mostly refering to that cost versus the 10 cents each I have gotten metal 2n2222 devices in the past.
I do finally have what should be a successful ssb spur mod configuration using a second 45 MHz xtal filter that doesn't wreck my 40m cw transmit, but my k1 relay stuck after I installed it. I have to put things back together to confirm it works. Won't have spurious data until later this month.
73 curt
|
There is a vendor on the'bay who is named "polida..." got good
components from them.
They replace lost stuff and guarantee genuine parts. They are on spring
holiday now!
At 01-02-20, you wrote:
toggle quoted message
Show quoted text
Hi Rob
If they come from China, don't bother. I went this same thing last spring
and they were all duds. You're better off getting them from a reliable
source.
73
Ken VA3ABN
On Fri, Jan 31, 2020 at 3:10 PM Rob French (KC4UPR)
<
robert@...> wrote:
- Hey guys,?? I'm looking to get some 2N2222A transistors for my
uBITX mods.?? Does the following appear a trustworthy
source?
- 2N2222A - Bipolar (BJT) Single Transistor, NPN, 40 V, 300 MHz, 1.2 W,
800 mA, 100 hFE (Pack of 50) (2N2222A)
- Otherwise,?? I was planning on the $2 each ones from Central at
Mouser.??
|
Hi Ted, can you share more details on your 5109 mod, I can mostly what you have done from the attached image but did you change any other components as well ?
What changes did you make to the resistors ?
Also did you change out the finals on this board to something else or is that just a repair ?
Thanks for your time!
Br Peter.
|
Hi, Peter.
I'm sorry for the delayed response. Please don't take it as a lack of interest in helping.?
I added a 22-ohm resistor to the bias resistors recommended in the case of other transistor swaps, i.e. R87 in the pre-driver, etc. Without the schematic handy, I'm hesitant to name all three instances where this is done but it's essentially the same bias change as if 2N2222's had been swapped for the 3904's.?
Another user a while back suggested simply going parallel with the similar, now disused resistor next to it i.e.R88 for the same objective.? That is, shunting across the non-grounded side of R87 & R88 is the same as nailing a second resistor on top of R87 - and it's easier.? So, that's one way you can do the bias adjustment when replacing two 3904's with one 5109.
About those finals: Note that the motherboard has been Dremmeled out a little behind the finals, to make room for a heat sink arrangement inside a steel hard drive case. I messed up and also let out the magic smoke from the original finals besides. My de-soldering skills are terrible and I also have nerve damage affecting my hands, and so you're looking at a poor repair, there. It is not pretty.... the radio works, though. ?
Best of luck, Peter, and do feel free to write again if I can help.
-Ted
|
Ted
Raj vu2zap