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

On 02/11/2023 10:37 PM Rex Harper <tunacankits@...> wrote:


Gangue,

I just hosed up my early TT2-EZ Build transmitter to my fairly accurate
PM-1300a dummy load/power meter. Powered from my portable Jackery, the
input voltage to the TT2 was 13.4 volts. The key down power was approx
.18W. I typed approx .18 on purpose. My college physics professor taught
me something very important in Physics 101. You can't read something
from a meter and write it down or say it is fact unless you can prove it
is fact. I'm looking at an un-calibrated analog meter with an unknown
full scale accuracy and see that the needle is between 150mW and 200mW
and slightly past the middle point between the two scale markings.? So
the .18W is MY best GUESS as to the power output from the transmitter. I
thought that the output was a little on the low side so I twiddled with
the power pot over by the crystal. Holding the key down while twiddling,
I raised the output power to about .48mW with minimum resistance on the
pot. I had no heat sink on the 2N3866 final transistor so I didn't key
down for too long....

I could have said my power readings were 180mW and 480mW but THAT would
convey accuracy that I can't actually read on my meter. YOUR mileage may
vary depending on kit parts, load variations and your technique of
measurement.

Rex? W1REX

On Fri, Feb 10, 2023 at 2:47 PM, Colin Evans M1BUU

<colin.evans2@...> wrote:

OK Daniel,

?

I've had my 40m tuna tin transmitters out on the bench. All of my 40m transmitters put out in the region of 400mW from a 12.6v regulated supply capable of 3 amps. My 12v supply is distributed via a reverse polarity protection diode (think it was a 1N5818). I have a TTT EZBuild that I built with toroids instead of RF chokes and that puts out around 850mW.

73, Colin

?

On 02/10/2023 10:49 AM Daniel KK4MRN via groups.io <sqldan2000@...> wrote:

Colin,
Can you get out your TTT EZB and test it?? I want to have numbers I can compare against.? ?I just want to be in the same ball park when it comes to power output.? ? If you have screen shots of oscilloscope, spectrum analyzer, etc... That would be cool to see as well.?

Is the radio in your photo a TTT EZB built?? And using Manhattan construction method?? Or is that some other radio?

I will be using a peak detector hooked up to a 50 ohm dummy load and a >10M ohm multimeter.? And I understand my equipment is not calibrated.? Just numbers to see what it is.? ?

73 Daniel KK4MRN