DAVE MADE M400

[AudioShockwav]

I still don't understand what you mean by Audio Feedback. Are you talking about the talkback on your radio?

My guess is the transformers on the output are buzzing with audio peaks, seen this before.
Sounds like audio coming out of the amp.
Me, I don't like 1×4 amps, too much current draw too much heat for the result when a stout dual final radio will wring the same amount of real power out of 4 2879's
And if you damage them, plan on replacing them all with HG, unless you have a stash of real Toshiba's.
I agree with the recommended 100 watt dead key.
73
Jeff

 

[9 DOUBLE ZERO MINI GRASS]

I still don't understand what you mean by Audio Feedback. Are you talking about the talkback on your radio? Is it RF bleeding into speakers in your shack?

Right now I think your power supply is not able to keep up and I don't know if the 100 amp will do much better. The next question would be is your watt meter a true peak reading meter?

What is the dead key and swing from your Cobra 29? If your carrier is too hi that can cause backwards swing. You want the amp to dead key out between 100-150 watts max.

At this point we will assume your antenna, coax, jumpers, and power feed lines and ground are all good and correct. Curious to see what the 100 amp power supply can

I still don't understand what you mean by Audio Feedback. Are you talking about the talkback on your radio? Is it RF bleeding into speakers in your shack?

Right now I think your power supply is not able to keep up and I don't know if the 100 amp will do much better. The next question would be is your watt meter a true peak reading meter?

What is the dead key and swing from your Cobra 29? If your carrier is too hi that can cause backwards swing. You want the amp to dead key out between 100-150 watts max.

At this point we will assume your antenna, coax, jumpers, and power feed lines and ground are all good and correct. Curious to see what the 100 amp power supply can do.

there is audible chatter coming from the amp when i key down and start talking. swr on channel 1 is flat. on channel 40 it is at 1.1. all coax, jumpers, and grounding is straight money.

 

[144inBama]

Newer parts from other suppliers are all you can buy since Toshiba quit making that part for good. None of them are as stout as the original Toshiba. How much 'competition' abuse they can take is an open question. Mostly you find out when they go "snap!".

From my own "Imma see what they'll do" test..... 18 VDC will kill an Hg in about 5 good keys and about 3 two minute keys. Hell, 16 VDC is stressing the daylights out of them. Wattage increases? At 18 VDC I gained about 1.5 times the watts from 13.6 VDC. The hfe on the transistors went to crap. New they were about 49 after the 18 VDC.....6-8. They had less than 10 minutes on them. I'm not sure they'd even survive a 20 VDC hit.
The 100 watt DK is correct.....if you want them to last. A straight 4, 1x4 or 2x4 is a 100 watt DK.
Hgs are all we have so the days of beating the guts out of your box is over, unless of course your pocket are endless.

 

[9 DOUBLE ZERO MINI GRASS]

From my own "Imma see what they'll do" test..... 18 VDC will kill an Hg in about 5 good keys and about 3 two minute keys. Hell, 16 VDC is stressing the daylights out of them. Wattage increases? At 18 VDC I gained about 1.5 times the watts from 13.6 VDC. The hfe on the transistors went to crap. New they were about 49 after the 18 VDC.....6-8. They had less than 10 minutes on them. I'm not sure they'd even survive a 20 VDC hit.
The 100 watt DK is correct.....if you want them to last. A straight 4, 1x4 or 2x4 is a 100 watt DK.
Hgs are all we have so the days of beating the guts out of your box is over, unless of course your pocket are endless.

planning on 14.5-15V only.

 

[9 DOUBLE ZERO MINI GRASS]

My guess is the transformers on the output are buzzing with audio peaks, seen this before.
Sounds like audio coming out of the amp.
Me, I don't like 1×4 amps, too much current draw too much heat for the result when a stout dual final radio will wring the same amount of real power out of 4 2879's
And if you damage them, plan on replacing them all with HG, unless you have a stash of real Toshiba's.
I agree with the recommended 100 watt dead key.
73
Jeff

Mahalo sir! yeah these have 4 toshiba red dots and one toshiba blue dot. so i don't want to mess this up! Appreciate ya!

 

[ShadowDelaware]

I have the same dave made original 1x4 in my truck and I am getting 750 to 800 out of it depending on engine rpm and carrier between 4 and 7 watts.

 

[Enterprise312ok]

The fastest way to see more watts is to get a bird 43p with a lithium 9 volt in it. I think a lot of people blow up their boxes trying to get there meter to show what a bird will on a YouTube video. A powered peak reading circuit makes quite a lot of difference in my experience.

 

[9C1Driver]

That's a great meter probably still the top of the line standard. If you really want to see those feel good watts get a loose Dosey. A class C amp being overdriven will really excite that Dosey into showing you watts that don't even exist.

 

[linearone]

That's a great meter probably still the top of the line standard. If you really want to see those feel good watts get a loose Dosey. A class C amp being overdriven will really excite that Dosey into showing you watts that don't even exist.

Honestly, in my experience I've noticed that a real bird 43P reads more peak watts than a well-adjusted dosey. And if you really want to see a lot of peak watts buy a CDI peak reading meter.
Most of the dosy meters that I've seen in the last 10 years or so have been calibrated pretty stingily compared to any of my birds.

Also, I'm still not clear if the original poster here that has the amplifier is using a peak reading meter or an average reading meter. If he's using an average reading meter, his box is working perfectly.

 

[144inBama]

I agree with the others. A lot of places have a "buy" meter and a "sell" meter. The "Buy" meter is a Bird and the "sell" is a Dosey. They use the Bird to buy your amp because it will 90% of the time show less watts. They'll use the Dosey to sell you an amp for opposite reason. Now, I've seen Doseys as tight or tighter than a Bird but there's a reason Bird has gotten so many Gov. contracts in the past, they're consistent.

 

[nomadradio]

real bird 43P reads more peak watts than a well-adjusted dosey.

For good reason. It's an "active" peak-reading circuit. The Dosy isn't so bad, especially for AM, but it uses a passive peak circuit. Will never quite match the reading from an active circuit. The higher the selected power range, the better it gets. Gotta come up with a clear graphic way to show why that is.

Some day.

73

 

[Dr_DX]

You said you run AM, but does the box have a SSB option? If so or even if not so, the bias maybe class "B" which is more linear for SSB use but less efficient, which means you aren't going to get as much out of it as a class C biased box. Chances are the boxes on Youtube are class C.