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Author Topic: zetagi b300p linear  (Read 4552 times)
GM1ZVJ
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Posts: 152




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« on: December 10, 2003, 04:31:35 PM »

Anyone know anything about this 20-30 mhz 400watt linear ?? well aware that this is a cb style intended amp, so please know comments regards this, I am aware off this fact !! just really looking for advice from anyone who has used / uses this particular linear or one very similar in style as I believe they are  also marketed under the name RM and possibly sycron ?? all european makes / markets. also thought this amp used to be advertised as having a 14 -30 mhz usable freq range but seem to advertise it as 20-30 mhz now ??!!

plans are to utilise it with my little ft817 with its 5 watt output, with obviously a little more output filtering added than amp is supplied having !!

any advice would be much appreciatted,

regards,
        john...
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WA9SVD
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Posts: 2198




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« Reply #1 on: December 10, 2003, 06:10:54 PM »

Hello John,
    Being an European model, most of us (here in the U.S.) can't help directly.  But if the amp IS suitable for 20-30 MHz, (with the additional filtering you suggest) it should be quite usable for 15 and 10 Meters, and your radio should be able to drive it sufficiently to get full output.

    For our (U.S. Hams) information, what are the regulations regarding "CB" type amplifiers?  Asy they as strict as here in the States?  QRP operators who wish to increase power on HF have quite a dilemma; amps that can be driven by the QRP level are basically illegal to manufacture or sell, (minimum drive requirement is supposed to be 50-100 Watts; a real waste when 5 W could do the same, but that's the law here!) so they either stay QRP or have to homebrew an amp, which can be a bit formidable for a multiband amp.
    Good luck on your project.  
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KG4PFO
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Posts: 174




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« Reply #2 on: December 11, 2003, 01:37:25 AM »

Go to www.rmitaly.com
You will find the amps there...the MFG.
Specs and prints....your right its a RM.
Built cheap with Min. parts.

KG4PFO
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W8JI
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Posts: 9296


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« Reply #3 on: December 11, 2003, 10:13:36 AM »

John,

Everyone seems to incorrectly think these miminum parts count poorly designed amplifiers only need an outut filter to make them acceptable.

That isn't true.

The one you have is not biased properly (it is non-linear) and obviously can't run the power advertised without considerable distortion and flattopping.

That means it will add keyclicks on CW and splatter nasty on SSB.

You'd need to do some serious rework to make it acceptable for amateur use, especially if you are going to use it at home on a reasonable antenna. It would need an active bias system, you'd need a good stiff power supply, and you'd have to add harmonic filtering.

Otherwise you would still sound like the others running cheap CB amplifiers, and tear up the band. The output filter doesn't help anything but harmonics, it does not help splatter or trash in the amateur bands.

73 Tom
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WA9SVD
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Posts: 2198




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« Reply #4 on: December 12, 2003, 09:19:43 PM »

Point taken Tom, but I assume (perhaps falsely) that a rework of an amp will also check for proper bias and distortion levels before an amp goes on the air.
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FP5CJ
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Posts: 5




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« Reply #5 on: January 02, 2004, 09:16:28 PM »

Hi!
I just got one, and I Wonder how many AMPS needs the power supply to run this mobile CB AMPLIFIER to the max power RATED around 300 WATTS IN SSB, I presume if 14 volts DC is used with the MAX 25 Watts input)?(PS of 30,35  or 40 AMPS??)
73
JP
FP5CJ
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KG4PFO
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Posts: 174




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« Reply #6 on: January 04, 2004, 09:53:10 PM »

30 amps is plenty........These have only 2 sd-1446 transisters and you will get around 150 watts on a bird watt meter.
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