Rex,
Thanks for the info. I ordered a few 2n2222a with T018 cases and some heat sinks for them. When I have a chance I'll try them out.
I have a few alternative analog SWR/Power meters built and will hook up my double needle meters and see if I can get them 'calibrated' against my other power reading sources. I do love the tweekiness of a good analog meter. It feels like your adding some art the the tuning process.? I always put in a transistor socket for the final since I ordered a tube of sockets a couple of years ago. I agree, for us tinkerers its the best idea.
I and another ham are giving a presentation on the (TR)uSDX to our club. I seem to have interested a few of the members to get that box and the QRP fun seems to be spreading in the group. I regularly bring my latest kits (many from you) to meetings. The other club I belong to is having a show and tell this week, I'll have a handful of rigs, test equipment .. there too. Some time this summer if you would like to do a zoom presentation or talk on QRP things let me know.? I love to spread the special pleasure of minimalism and portability.?
? ? ---John AC9UV
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? ? ?73
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On 02/12/2023 11:07 AM Rex Harper <tunacankits@...> wrote:
On 2/12/2023 2:42 AM, John Putnum, AC9UV wrote:
Rex,
Interesting. Your TT2-EZ has a 2N3866 final transistor where the current
design of the Two Tinned Tuna -EZ build uses a 2n2222a for the final. Is that a change? would a heat sinked 2n3866 give more output power? would that be an possible modification?
Thanks, 2n222
---John AC9UV
Gangue,
From the very beginning of QRPme kitting, I have included a SIP socket in my kits for not only using as a crystal socket but also as a transistor socket for the final transistor. Easily replacing a final or even better...experimenting with other transistors as finals has been a hallmark of my efforts to enable others to have FUN with their kits. So the EZB does come with a pair of PN2222 transistors for the oscillator and final. It also comes with a SIP socket and very clearly in the builders guide shows how to use it as sockets for both the crystal and final transistor.
I like the 2N3866 as I have plenty due to getting them for a VERY good price from the GQRP Club! I pop them in my builds and some kits primarily because they are TO5 cans and finding heat sinks for TO5 cans is much easier than finding sinks for TO18s (2N2222A) or TO92s (PN2222). Consulting the datasheets:
transistor? pkg?? Max collector current watts dissipation
2N2219A?? TO39??? 600mA/800pk ?? ??? ??? ??? 3W
2N2222A? TO18???? 600mA/800pk ?? ?? ??? ??? 1.8W
PN2222A? TO92??? 600mA? ????? ??? ?? ?? ??? ? ?? 625mW
2N3866??? TO39??? 400mA??? ??? ??? ??? ??? ??? ??? 1W
I'd rather 'push' a whoosier final WITH a heat sink than a marginally better transistor without one... AND trying to find obsolete 2N2219A s and 2N2222s in cans is a challenge along with coming up with the coin to buy them! Jameco Electronics has 2N2222A transistors at $1.29ea which is a little cheaper than they used to be but no heat sinks for them. But their performance in the EZB is not that much better. I yanked the 2N3866 in my EZB that I tested last night and plugged in a PN2222. Power readings were pretty much the same without touching the trimmer pot. I suspect that if you wanted to run higher supply voltages you would start to bump into the collector current and heat dissipation limits and start to melt epoxy.
I really wanted to be in Orlando this weekend for the Hamcation! When my dad was alive and less than a hour away, I would take in the show nearly every year. The low rent building out back was my GOTO source for things like NOS heat sinks etc. Another GOTO place is Skycraft Surplus. Apparently they have moved into a bigger space since I last visited them....and bought every TO5 heat sink in their bin. I had 150+ in my suitcase on the way home. Long since used up but more easily findable than a TO92 or TO18 heat sink. They sell online but not as much FUN as being there in person and getting the full touchie feelie experience. They make the old RS stores look like an end cap in a truck stop convenience store!
Rex? W1REX
