TX project advice


Jon Wanzer <jon@...>
 

Greetings Everyone,

I finally have my 40 meter DC receiver in band and working well and the helically wound vertical is all but done. While I want to tweak the AF amp and do some filtering my biggest concern is actually getting on the air before FD.

To this end, I need to build a transmitter. My specifications are... 40 meter, under 5 watts, simple design, commonly/currently available and inexpensive or easily manufactured parts, and now the kicker SSB/CW.

A tall order but hey, you guys, and gals, are the ones who would know. I am skilled in assembly but my EE/RF design skills are still in there infancy. Any suggestions in this area would be greatly appreciated.

​72/​
73,

~Jon Wanzer KK6GXG

(408) 515-3583
jon@... | www.KK6GXG.com


Bill Cromwell
 

Hi Jon,

Do you have a suitable filter around which to build transmitter? the TX does NOT need a CW bandwidth filter. there are many SSB bandwidth filters ar hamfests and on eBay. Maybe a list member has one you can get. The 3.395 mc filters for Heath and other radios seem common as dirt. Once you have that filter the rest is much easier.

You might have good luck with a phasing SSB rig, too. A combination of of fixed frequency (at IF frequency) and less stringent, homebrew ladder filter can give pretty good results (or so others have testified).

73,

Bill KU8H

On 05/08/2015 02:05 PM, Jon Wanzer jon@kk6gxg.com [4sqrp] wrote:
Greetings Everyone,

I finally have my 40 meter DC receiver in band and working well and the helically wound vertical is all but done. While I want to tweak the AF amp and do some filtering my biggest concern is actually getting on the air before FD.

To this end, I need to build a transmitter. My specifications are... 40 meter, under 5 watts, simple design, commonly/currently available and inexpensive or easily manufactured parts, and now the kicker SSB/CW.

A tall order but hey, you guys, and gals, are the ones who would know. I am skilled in assembly but my EE/RF design skills are still in there infancy. Any suggestions in this area would be greatly appreciated.

​ 72/​
73,

~Jon Wanzer KK6GXG

(408) 515-3583
jon@KK6GXG.com | www.KK6GXG.com <http://www.KK6GXG.com>
------------------------------------------------------------------------


Donald Kelly
 

Jon - Congratulations on building your DC receiver. Not many people build from scratch and even fewer build receivers.

 

Just a thought for future experimentation. You have “Experimental Methods in RF Design”. Later in the book you will find KK7B’s section on higher performance DC receivers.

They are a lot of fun to build.

 

A good first transmitter design might include W7ZOI’s Universal QRP Transmitter. It is a 1 to 1.5W transmitter using very available parts. It can be a driver for a more powerful TX later on.

 

This is a good reproduction I found on the WEB. I could send you a copy of the chapter from “Solid State Design for the Radio Amateur”. It is a classic MOPA format that modernized the

legendary designs like the 6AG7/6L6 transmitters many of us used as Novices.

 

http://www.qsl.net/k0kp/hbrew/qrp_sch.html

 

It is a limited transmitter but will teach you a lot about TX construction. I have used various power amplifiers over the years.

I casually operated 1.5W with a DC receiver and a simple TX like this for over a year and logged 40 state and 3 foreign countries.

 

 

 

This is a 20W transmitter I built a few years ago. The basic driver is about 1W driving a 2SC1307. It is VXO and covers about 6KHz.

 

http://i732.photobucket.com/albums/ww328/Don_K5UOS/100_1786.jpg

 

Good luck with your project.

 

K5UOS

 

 

 

 

From: 4sqrp@... [mailto:4sqrp@...]
Sent: Friday, May 08, 2015 1:05 PM
To: qrp-l@...; qrp-tech@...; 4sqrp@...; ba_radio_builders@...
Subject: [4sqrp] TX project advice

 

 

Greetings Everyone,

 

I finally have my 40 meter DC receiver in band and working well and the helically wound vertical is all but done. While I want to tweak the AF amp and do some filtering my biggest concern is actually getting on the air before FD.

 

To this end, I need to build a transmitter. My specifications are... 40 meter, under 5 watts, simple design, commonly/currently available and inexpensive or easily manufactured parts, and now the kicker SSB/CW.

 

A tall order but hey, you guys, and gals, are the ones who would know. I am skilled in assembly but my EE/RF design skills are still in there infancy. Any suggestions in this area would be greatly appreciated.


​72/​

73,

~Jon Wanzer KK6GXG

(408) 515-3583
jon@... | www.KK6GXG.com