Considering adding 160 meters to my Swan Mark 1 amplifier. The power supply and RF deck were overhauled in 2003. At that time a new transformer was also added to replace the shorted out original o
Thank you all for your insights in this matter. It seem like my original thought to tweak the Q is not very good. The two dominating suggestions are: 1, add a smaller C1 to the existing and switch in
A 6 mix iron powder is good for 6-10M, I use it as the L in the input pi Straight from the Micrometals spec sheets and then some testing. There is a huge difference between using it in a SS HF VFO an
On Jan 31, 2005, at 2:38 AM, Angel Vilaseca wrote: I am building a 3.5 to 30 MHz amp and I have been following this interesting thread. I have a question about the *other* choke in the output circuit
I am building a 3.5 to 30 MHz amp and I have been following this interesting thread. I have a question about the *other* choke in the output circuit, that is the one that is wired between the antenna
I picked up one of these amps, it only has a 40 meter tank circuit in it. Thinking about Ferrite ToroidTank Circuit? I know i'll have to wind my own coil- what size wire would be best? It is a good
That is some great info Marv...gotta save that one to the printer! The ARC-27 was a Collins 200-400MHz airborne TX from the 50-60's era. Select a channel from the remote head and wait a minute while
a Hi Carl, I found that RG-402 trick just as interesting when I first saw it. I am currently involved in an update of my own ridiculous amplifier and I may just drop one of those coils in for the sak
Hello Skip & all... "No tune" vacuum tube power amplifiers: All the practical ones (i.e., NOT distributed amps with 8++ tubes and efficiency <30%) are really band-pass, not broadband. Most hams have
Hello again, I have a question about the No Tune type of amplifiers that are/were offered for sale to amateurs through the years. Would one of you take a moment to mention the makeup and consideratio
There is a copy of the G3SEK article here: https://www.tmchistory.org/tmc_restoration/PAL-500/power and protection for modern tetrodes.pdf 73, Mike W4EF...............................................
Hi, It is based on a lm741 op amp (if I remember correctly) steering an N channel mosfet shunt regulator. The reference is two 1% resistors and a multi turn potentiometer (it only moves the voltage b
Luk, Are you using the PA0FRI screen regulator circuit? If so, won't you need more than 360 Vdc input? 73, Mike W4EF................. Could someone please verify J chose the voltage correctly, please
I decided to replace the auto transformer arrangement with a custom wound 230 - 2*130V transformer. Could someone please verify J chose the voltage correctly, please? I need 350V at 45mA max. The shu
Now that you say it that way I start suspecting the auto transformer. Assuming nothing is miswired (and I have to rewire anyway to route the wires nicely - currently it's only a "working" setup) it i
Beware that the black epoxied Mica cylindrical capacitors are largely intended for broadcast band use, found in transmitters and antenna tuning units (ATU). They also can work in induction heating ge
Here the manually tuned, tuned input is installed. Typ a pair of 4 section broadcast caps are used for this application...and has been used several times in the past. (17-540 pf per section, and all
Jim, On the comparison between a PI and a PI-L network: PI needs to be run at a higher Q than the PI-L for the same stopband attenuation resulting in sharper tuning as you QSY. PI needs 1 fewer poles
Jim, I have often wondered this very thing and recently built several filters and have made several measurements. The effects of coupling between the coils are primarily stopband attenuation. Small a
I've been noodling around various tank circuit possibilities for a 160m monoband amplifier. A pi-L network isn't very practical for an 8877 because the relatively high plate impedance mandates very l