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Re: [Amps] Drake amplifier

To: "Roger" <>, <>
Subject: Re: [Amps] Drake amplifier
From: "jeremy-ca" <>
Date: Mon, 23 Jul 2007 17:22:43 -0400
List-post: <>
Your slight technicality is a later revision to the regs, the FCC was having 
a problem defining the power so that  advertising wording and tuning 
instructions didnt break rules.

In 1963 1000W DC input meant exactly that. Key down, A0, steady carrier, 
however you want to define it. Pulse keying tuning was also illegal except 
into a dummy load.

National was questioned about their 2KW specs by the FCC, ARRL (for ad 
purposes), and many hams. Nationals defined voltage and current in the SSB 
position easily exceeded 2KW; 2500V @400ma indicated on voice peaks since 
key down in the SSB position barely got the voltage down to 2500 @ 900ma and 
output was typically 1400W. They used a very healthy xfmr and a slow meter.

National and others forced the FCC to clarify the rules. There are still on 
the air and Internet arguments as to what defines PEP.

And then RF speech processors came along in that year such as the Comdel. I 
still have mine!

Now they have amps advertised regularly that will do 2200-2500W out and no 
one cares any longer. How many out there drop the drive to their 8877 amp to 
60-65W in order to be legal?


----- Original Message ----- 
From: "Roger" <>
To: <>
Sent: Monday, July 23, 2007 3:59 PM
Subject: Re: [Amps] Drake amplifier

>> 1KW input on CW, 2KW PEP on SSB was the FCC reg back then. For that 
>> reason
> Maybe a slight technicality, but the power limit was "1 KW AVERAGE dc 
> input
> measured using a current meter with a 1/4 aecond time constant. There was
> only one limit, not seperate ones for CW and SSB. In grounded grid you 
> were
> supposed to add the exciter input to the amp input when figuring the legal
> limit.
> PEP varied widely on input and output due to voice characteristcs.  On the
> two "legal limit" amps I ran back then I consistently ran 2 KW PEP 
> "output"
>> many amps of that era had a CW/SSB plate voltage switch. Many left it in
>> the
>> SSB position irregardless of the mode (;  No sense in throwing away 3dB 
>> in
>> a
>> pileup.
> The CW position was also a tune-up position that allowed tuning for tilt,
> then switching to SSB with a higher plate voltage and not having to 
> retune.
> Actually many of the amps used voltage doublers and if you tuned up in the
> SSB position it'd drag the voltage down to the point they'd be mistuned
> running SSB. My old Alpha 76A has a heavy enough power supply but the 
> manual
> still has you tune in the CW position to prevent over heating the tubes.
> 73
> Roger (K8RI)
>> Carl
>> KM1H
>> ----- Original Message ----- 
>> From: <>
>> To: <>; <>
>> Sent: Monday, July 23, 2007 12:33 PM
>> Subject: Re: [Amps] Drake amplifier
>>> In a message dated 7/23/2007 12:21:44 P.M. Eastern Daylight Time,
>>> writes:
>>> I have a  drake L7 amp.
>>> How much power out do you typically get from a drake L4 or L7  amp? I
>>> have
>>> 95
>>> watts drive and get just short of 1100 watts on 40  meters.
>>> The amp's wattmeter and a bird wattmeter with a brand new slug  agree
>>> almost
>>> exactly.
>>> This seems a little low or is that about all  that can be expected from
>>> the
>>> 3-500Z's. They run at 2450 volts on the  plates and 230 ma grid current.
>>> Thanks
>>> Gary   K4FMX
>>> Hi Gary, Yup, that is about right 110-1200 watts out with around 100
>>> watts
>>> of drive.  If you have a look at an AL-82, it will do about 1600 watts
>>> out
>>> with 100 watts in.  The difference is in the fact that the Ameritron
>>> AL-82
>>> runs
>>> the anode at about 3600-3700 volts.  The extra plate voltage really
>>> makes
>>> the
>>> 3-500Z's play great.  The "HOT" set up for the Drake L4 or L7  would be
>>> to
>>> build up a better HV supply.  The Drake tank circuit can take  4KV no
>>> problem.
>>> But what you are seeing now is right on the money.   You have to 
>>> remember
>>> that
>>> when the L4/L7 were made, the maximum power  permissible by the FCC was
>>> ONE
>>> KILOWATT DC INPUT.  That being so, the amp  companies did not run a pair
>>> of
>>> 3-500's to their full potential so they got by  with wimpy power
>>> supplies.
>>> Put a
>>> good power supply on an L4 and it will  perform nicely.  Easy legal 
>>> limit
>>> amp
>>> plus.  Oddly, the Drake RF deck  makes a great conversion to an 8877 and
>>> handles the 2KW easily.
>>> 73 Lou
>>> ************************************** Get a sneak peek of the all-new
>>> AOL
>>> at
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