Input on an idea

[Cody Dixson]

I've been tossing around the idea of buying a rci 2970n4 and gutting the amp.

Instead of the Mosfets I'd really like to replace the entire thing with a 2 or 4 pill ldmos amplifier.

Is the squeeze worth the juice?

 

[Shockwave]

I've been tossing around the idea of buying a rci 2970n4 and gutting the amp.

Instead of the Mosfets I'd really like to replace the entire thing with a 2 or 4 pill ldmos amplifier.

The heatsink is too small to keep anything larger, cool. The 12 volt power source won't run LDMOS. The only real compatible choices with the existing power source and heatsink, are the MRF454, 2SC3240 or the RD100HFF1. All will require circuit changes.

 

[9C1Driver]

In order to frankenstein a radio like that you are going to have to know how to re-work or re-engineer probably half the radio. I hope your good at modding surface mount boards. If you were to pay someone to do the work you might have several thousand dollars in just labor. And when it's done how well will it work and for how long?

 

[Shockwave]

In order to frankenstein a radio like that you are going to have to know how to re-work or re-engineer probably half the radio. I hope your good at modding surface mount boards. If you were to pay someone to do the work you might have several thousand dollars in just labor. And when it's done how well will it work and for how long?

Reminds me of the customer that was determined to change the final in his Tram D201 in order to get it to make at least 100 watts. Refused to just add a linear to get to the 100 watt level and had to have it high level, plate modulated at the 100 watt goal. Because I didn't want to do the job, I threw what I felt like was a ridiculous price out at $1,000. He pulled his wallet out, dropped ten, hundred dollar bills on the bench and extended his hand to shake on the deal.

I knew it was going to require replacing the modulator and final tubes with 6146B's. The plate and modulation transformers would need replacing too. What I didn't expect was having to rewire the modulated B+ away from the mode switch and through a HV relay. Found that out after toasting a wafer on the switch and replacing it. Both the final and modulator needed additional screen regulation to achieve the strong positive peaks the customer wanted. Then, the whole thing sucked on SSB and needed modification to the final neutralization circuit, to get the carrier out of the SSB.

Charged by the hour, it would have been double what I got. But, the customer got the only 140 watt PEP D201 with a variable on it, that I've even seen. In retrospect, I wish I had that radio now. The radio outlived the owner and I have no idea where it went today. If your Tram's ANL knob, adjusts your RF output from zero to 140 watts PEP, you're the lucky winner. It's an original hand wired VOX Tram with the 40 channel crystal board installed and matching VFO dial, from a D-201A (grey channel switch too).

 

[nomadradio]

It's an original hand wired VOX Tram with the 40 channel crystal board

A real Fronkensteen.

73

 

[Shockwave]

A real Fronkensteen.

73

It was clean and without look inside by someone familiar, you would never know it wasn't stock. No extra holes or outside appendages. Even the transformers went into the stock locations. An old D&A triple stage, gave up one of its transformers for B+ and filament. The real giveaway was the plate caps (insulated) on the 6146B's and the radio had 17 tubes rather than 15. Two 0B2 screen voltage regulator tubes glowed in step with the modulation.

 

[Cody Dixson]

@Shockwave @9C1Driver @nomadradio I figured I was opening a massive can of worms lol thank you all for the input.

The main reason I want something different than my current set up is stability. People tell me I drift bad on ssb and being as green as I am I figured it's my radio a Galaxy dx98vhp. So I thought let's get one with a frequency counter that reads more than 5 digits to insure stability. The ldmos transistors from what I've seen are indestructible on the output side so it's idea or cost effective for someone new to amplifiers, it wasn't untill today after making this post that I watched bbi build his 4 pill driver that I realized it was gonna be a project project.

What I'm picking up is im better off getting a good stable radio and setting a 2 pill in line driving something like a 4 pill ldmos the dx98vhp seems to work fine and I've reached British Columbia from Arkansas on a 102 whip. I'm just not a fan of the location of the amp and the fact that it's always on. I've got a lot to learn.

I had a guy offer me an 8 pill fat boy for 1k but after hearing he was putting 140 amps into it to get his 2k watt pep I'm very hesitant.

 

[9C1Driver]

Cody if you talk a decent bit of SSB a Galaxy radio is just not going to do it for you. They tend to drift, some more then others. Years ago a local had a Galaxy 98VHP in his tow truck. Once warmed up and on frequency he sounded great. Then he would be gone for ten minutes loading a car up and when he would key back up he sounded like he just sucked on a helium balloon. It drove him mad and he sold it.

Try and look for a radio that is processor controlled like a Stryker 955, RCI 2950, Anytone 5555 or 6666. The most stable export I have right now is a Magnum 1 and I love it. It has what is called a TCXO circuit in it. There are other good options as well I just named a few. Good luck.