[AMRadio] Re: Ranger... good news, bad news


Gary Schafer garyschafer at comcast.net
Wed Nov 8 11:59:20 EST 2006


I have never had a ranger hooked to an SB200 but it sounds to me that 12 to
15 watts is not enough drive for it. The SB200 has a gain of about 6 if I
remember right.
That means that 100 watts of drive will give 600 watts output.
If you want 125 watts carrier output that requires the amp be capable of 500
watts output for peak audio.

500 watts output divided by 6 = 83 watts PEP. Divide that by 4 and that says
that you need around 20 watts carrier.
Working that the other way says that 20 watts carrier drive times 6 (the
amplification factor of the amp) = 120 watts carrier out.

So unless you have some higher gain tubes in the amp 12 to 15 watts drive
will not be enough drive.

Now you can tune and load the amp to get the 125 watts out with lower drive
but it won't be linear.

73
Gary  K4FMX

> -----Original Message-----
> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> bounces at mailman.qth.net] On Behalf Of ne1s
> Sent: Wednesday, November 08, 2006 10:53 AM
> To: Discussion of AM Radio in the Amateur Service
> Subject: [AMRadio] Re: Ranger... good news, bad news
> 
> Jack Schmidling writes:
> 
> > I tried the accessory plug mod as suggested, removing 2/6 and putting a
> > meter across 2/4 and it works but the power is less than useful.  It
> less
> > than 5 watts and would only modulate about 25%.
> >
> > Did I do something wrong?
> >
> 
> It sounds like you did it right - there's not much to screw up. Maybe the
> Ranger has a problem. I get about 12W out from that connection. My Ranger
> power supply is not stock, but the voltages are pretty close. However, 15W
> is what I hear reported from others who have done this.
> 
> It helps to reduce the grid drive a bit in the low power mode - adjust the
> drive pot for maximum RF out of the Ranger - but it won't make the
> difference between 5W and 12W out.
> 
> And you should have absolutely no problem modulating to 100% positive and
> beyond if your audio is phased correctly and the modulator is working
> correctly; especially using the low power mod where you should have plenty
> of audio power to spare.
> 
> How much RF carrier do you get out of the Ranger when operating normally,
> and are you able to modulate 100% then?
> 
> 73,
>  -Larry/NE1S
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