开云体育

Mr. Rob... Can you please remind me what the low frequency attenuation was for your AMP-4? Thanks! Joseph

Spot on... As I stated in my group posting, the original driver is old, and a less efficient speaker can be had when using more power. My MS-4 was treated to a hardwood ply escutcheon to mount the

Frank, I am running the audio out of my R4C into a CLEAR SPEECH noise filter, then....from the noise filter into a Kenwood SP-940 speaker with 3 filters in it. Absolute Nirvana sound...Can pick up

Jim I just hooked my older counter and it is reading 152 MHZ plus it minus. Now which one is right? Maybe this one where the voltage is so high. Maybe I should put a ground on RFC505 and see what

Forget that idea as I turned the TR7 off and that frequency did not go away. Guess next it to try and measure voltages on both VCO’s and see if that will show the bad part etc. Jim VE1RB

My AMP-4 feedback loop was designed for about a 3 dB roll-off at 3 kHz. Personal choice. Rob, NC0B

Jim maybe this will help. I touched up several solder joints although they didn’t look good but not cracked. I switched the input to the counter and it is reading 17 to 18 mhz as the frequency is

All the talk about the audio amplifier on an R-4C intrigues me to ask the question, “What are you doing about the speaker?” With a 50 year old speaker in some cases, what are you replacing it

Gary!!! Bravo! I too used a device like that for mine( TDA7377)... I removed the original jensen speaker, used a lower efficiency driver, yet one with better listening specs. My MS-4 has been modified

I've seen that board on Osh Park. I like the purple one. :D "Paul Christensen via groups.io" <w9ac@...> wrote: -- 73 -Jim NU0C

Yeah, that works. The TDA chips are rock stable and practically bulletproof when implemented properly. I have one of the Velleman TDA2002 modules that I acquired some years back for my R4C, I just

The TDA series and LM380 are fine although I wanted lower noise with no detectable hiss at any setting of the AF control when using studio-grade headphones. The image below shows a discrete class AB

Good ideas Jim and I will get at doing that today. It is windy and raining here quite hard. A good job inside hi hi. I will let you know how it goes. Many thanks for the suggestions and help. Jim

It's a waste of time and money to design an AF amp for the Drake. I used a (now) 75cent complete TDA2030 module from china. Like this one:

At this point I am suspicious of that 1.3 MHz reading. That may be a spurious reading. It seems to me that the VCO should not be able to run there. What is the level of the signal? The frequency

FWIW the TR7 uses an LM380. It works pretty well. "Mike Bryce via groups.io" <prosolar@...> wrote: -- 73 -Jim NU0C

Rob, There’s always the possibility of starting over, making the changes to the artwork as necessary to use newer parts and or different parts with different footprints. I have time to do a few…

Using a doubler off the fil line has been done before.? ?We used a doubler (FWD) and used the 5.0 vac fil on the drake L4B fil xfmr sec winding....to obtain? 12.74 vdc (after V drop from? both

Yes Gary I did the ground on RFC505? when looking at the frequency on the counter and it does drop a lot. So I guess you are saying the High VCO is oscillating at 1.3 MHz . If that is the case there

Right now, just a power supply. I am considering letting go of my A Line (late s/n, the transmitter is essentially an T-4XB) and my L7 (has a Harbach board, graphite tubes and I reworked the power