Zetagi B-300P Need advice on amp installation

[Miura]

I’ve just got hold of a Zetagi B300P linear + preamp. I’m totally new to amps settings and how it works.
Hence I have a few questions for the knowledgeable chaps around here
What does pre amp mean and what is it used for? Should it be always on?
How many watts should the hosting radio be putting out to the amp on am and ssb?
and now the stupid question: Where should I locate my external SWR meter? in between the amp & the radio or in between the amp and the antenna?

 

[Riverman]

I’ve just got hold of a Zetagi B300P linear + preamp. I’m totally new to amps settings and how it works.
Hence I have a few questions for the knowledgeable chaps around here
What does pre amp mean and what is it used for? Should it be always on?
How many watts should the hosting radio be putting out to the amp on am and ssb?
and now the stupid question: Where should I locate my external SWR meter? in between the amp & the radio or in between the amp and the antenna?

The Preamp increases your receive capability. Allows you to hear weaker signals better. Use as needed.

1 or 1 1/2 watts is ideal. No more than 2.

Pecking Order:
Radio
Amp
SWR Meter
Antenna

That should fix you up.

 

[GlocknSpiel]

You'll need at least an additional 40A power supply. This is usually not a problem in a mobile installation, but you'll need a big power supply if not.

 

[Riverman]

The maximum draw on that model is 20 amps.
https://www.rigpix.com/linears/zetagi_b300p.htm
A 30 amp power supply should be fine for it and a radio if using it as a base. IMHO.

 

[GlocknSpiel]

The maximum draw on that model is 20 amps.
https://www.rigpix.com/linears/zetagi_b300p.htm
A 30 amp power supply should be fine for it and a radio if using it as a base. IMHO.

I thought it was capable of 400W pep. If all it can do is 120W, sure, a 20A should do finel. I'll have to check the specs on that amp again.

 

[Riverman]

Specs show 150 AM and 250 SSB. (See link in my previous post.)

 

[GlocknSpiel]

Specs show 150 AM and 250 SSB. (See link in my previous post.)

Yep, 20A should be adequate then (barely);
P/E=I
OR
250W / 12V = 20.8A
So 30A supply would be perfect.

 

[BJ radionut]

Best remember if 250 watts OUT...then roughly 500 watts input!!
Plus radio + pre-amp drain = ???
500 / 13.8v = slightly more than 36 amps... x 125% (for headroom) = 45 amps
My 2 cents
All the Best
Gary

20 amp max specs that amp =140 - 160 PEP at best output
20 x 13.8 = 276 watts INPUT x 60% efficiency = 165 watts max output

 

[GlocknSpiel]

Best remember if 250 watts OUT...then roughly 500 watts input!!
Plus radio + pre-amp drain = ???
500 / 13.8v = slightly more than 36 amps... x 125% (for headroom) = 45 amps
My 2 cents
All the Best
Gary

20 amp max specs that amp =140 - 160 PEP at best output
20 x 13.8 = 276 watts INPUT x 60% efficiency = 165 watts max output

LOL!! OK, let's just go with 60A to be safe. This cannot end well. So I'm out.

 

[Riverman]

I'm out.

 

[Miura]

I'm out.

River man, Thank you very much for all your advice! I now have a much clearer idea of how to operate it. Very useful Info. Power supply is 50 amps so it should do the work. Now my only problem is to get 1 or 1.5 watts out of my radio…it’s minimum being 4W I believe.
Many thanks also to all the chaps who chipped in. I should be sorted now. I will revert and let you know how things went
cheers!

 

[Miura]

LOL!! OK, let's just go with 60A to be safe. This cannot end well. So I'm out.

Radio is a base station with its own PSU. So zetagi amp will be alone feeding on my external power supply. hence 30 amps should be adequate…

 

[BJ radionut]

Never ceases to amaze me when "reality" show RF output meets true mathematics, someone's lower posterior always gets bruised.

20 amp max specs that amp =140 - 160 PEP at best output
20 x 13.8 = 276 watts INPUT x 60% efficiency = 165 watts max output

 

[Riverman]

Never ceases to amaze me when "reality" show RF output meets true mathematics, someone's lower posterior always gets bruised.

Gary, you need an “s” on the end of “show”.
Reality is singular. It should read, “. . . when reality shows RF output . . .

Just sayin’.

 

[BJ radionut]

MRF455 datasheet(1/4 Pages) MOTOROLA

1MRF455MOTOROLA RF DEVICE DATAThe RF LineNPN SiliconRF Power Transistor. . . designed for power amplifier applications in industrial, commercial andamateur radio equipment to 30 MHz.• Specified 12.5 Volt, 30 MHz Characteristics —Output Power = 60 Watts Datasheet search, datasheets, Datasheet...

html.alldatasheet.com

Motorola shows matched pair rating of 175 watts out...

275 watts input (20-amp x 13.8v)
Zetagi shows 200 watts AM/FM ...Output
This would require amp to be 73% efficient

Up to 400 watts SSB.
Hmm on a 20-amp supply. OK

https://www.g7syw.com/files/zetagi-b300p-schematic.pdf

Home - English - Zetagi

CATALOGCOMPANYCONTACTS CATALOGCOMPANYCONTACTSProduction and supply of radio devices and electronic equipmentFIND OUT MOREPower Supplies & Radio Communication EquipmentsAccessories for Amateur Radio & CBAntenna MatcherPower SupplyBattery Charger General PurposeInverter DC-DC Galvanic...

www.zgitaly.it

Something interesting here... 275 watts input (20-amp x 13.8v) = 400 watts out.

http://www.cbradio.nl/zetagi/Manual_Zetagi_B300P_ENG_ITA.pdf