[TenTec] In praise of older technology

Sun Mar 2 12:28:08 EST 2014

Oh yes, I've encountered those that are "backwards" in tuning as well.  Even 
in a commercial product as I recall.

But for a grounded grid linear amp, always adjust TUNE  for maximum output 
which should also be at the peak of the grid current.

73
Bob, K4TAX

----- Original Message ----- 
From: "Rick - DJ0IP / NJ0IP" <Rick at DJ0IP.de>
To: "'Discussion of Ten-Tec Equipment'" <tentec at contesting.com>
Sent: Sunday, March 02, 2014 1:58 AM
Subject: Re: [TenTec] In praise of older technology

> Bob, I'm glad you added this "clarifier".
> "The right side of resonance" is only true when minimum capacitance is
> clockwise and max is CCW.
> Normally that is the case but it might be a bit risky to assume it always
> is.  It is always better to know.  The best way to know for sure is to 
> pull
> the cover and look.
>
> I don't recall ever seeing a commercial amp that didn't work like that, 
> but
> I have seen some home-brew amps that were built backwards.  Easy enough to
> fix; just rotate the Plate Tune knob 180 degrees.
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Bob 
> McGraw
> - K4TAX
> Sent: Sunday, March 02, 2014 4:03 AM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] In praise of older technology
>
> I comes from many years of tuning AM broadcast transmitters.  The "right
> side of resonance" refers to adjusting the tank circuit tuning capacitor 
> to
> a slightly lesser value of C which is normally turning the knob to the
> right. One will notice a slight increase in plate current, otherwise a bit
> more than the current at the actual "dip" value.  Typically about a 2% to 
> 5%
> increase is adequate.  For my RCA BT the dip is about 425 ma and I run it 
> at
> about 435 ma for 3300 volts DC.
>
> With this method one will notice an increase in output power when tuned to
> the "right side of resonance" by a few milliamps while tuning to the "left
> side of resonance" the same amount will show a decrease in output.  The
> input power remains the same for both cases but the output is greater in 
> one
> case and less in the other case.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message -----
> From: "Kim Elmore" <cw_de_n5op at sbcglobal.net>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Saturday, March 01, 2014 8:41 PM
> Subject: Re: [TenTec] In praise of older technology
>
>
>> I've never been told of this trick for tuning for maximum efficiency of a
>> class C amplifier. Is there someplace I can go to learn a bit more about
>> it? I ask because I have a WRL Globe Champion AM transmitter (my Dad had
>> it before me and it's the first rig I ever operated) and this trick isn't
>> mentioned anywhere in the manual. My Dad never mentioned it to me, 
>> either,
>
>> but that may not mean much as he may have thought the nuance wasn't worth
>> the risk of damage. But then, there's a lot that isn't in the manual and 
>> a
>
>> lot of my Dad's knowledge that I never had a chance to have passed to me.
>> If this is one of the tricks that all the old hams used to know, I'd like
>> to know it, too.
>>
>> Kim N5OP
>>
>>
>> On 3/1/2014 6:55 PM, Bob McGraw - K4TAX wrote:
>>> Yes in a Class C amplifier one typically will adjust the plate circuit
>>> tuning for a dip in plate current.  Then one should adjust coupling for
>>> rated plate current or rated output. Then adjust the plate tuning to the
>>> "for right side of resonance", typically increasing PA current about 5%
>>> which will produce maximum efficiency.  All of this applies to only 
>>> Class
>
>>> C amplifier stages.
>>>
>>> In a linear amplifier, adjust plate circuit tuning for maximum output
>>> which should also be at the same point as the peak in grid current. 
>>> Then
>
>>> work your way up the power scale by increasing drive while adjusting
>>> loading to keep grid current and plate current at or below maximum
>>> ratings.  Once the rated grid and plate current values are attained,
>>> controlled by drive,  the last step is a very minor adjustment of plate
>>> tuning for maximum output.
>>>
>>> Remember should one use light loading with a linear amplifier, splatter
>>> abounds!
>>>
>>> 73
>>> Bob, K4TAX
>>>
>>>
>>>
>>>
>>>
>>>
>>> ----- Original Message ----- From: "Rick - DJ0IP / NJ0IP" 
>>> <Rick at DJ0IP.de>
>>> To: "'Discussion of Ten-Tec Equipment'" <tentec at contesting.com>
>>> Sent: Saturday, March 01, 2014 4:14 PM
>>> Subject: Re: [TenTec] In praise of older technology
>>>
>>>
>>>> "Dip" was pre-watt meter days.
>>>> No need to dip anymore.
>>>>
>>>> Just tune for maximum smoke!
>>>>
>>>> Precisely, running full drive power, you first tune the PLATE for max
>>>> smoke,
>>>> then repeat the sequence of slowly advancing the LOAD and peaking the
>>>> PLATE
>>>> for max smoke.
>>>> If you reach the point where increasing the LOAD and peaking the plate
>>>> brings no more increase in max smoke, but just an increase in Ig, then
>>>> you've gone too far. Back it off.
>>>>
>>>> The idea is to find the exact point where max smoke is reached with min
>>>> LOAD
>>>> that can achieve it - and of course all of this is always subject to 
>>>> the
>
>>>> Ig
>>>> not exceeding max specs.
>>>>
>>>> Piece of cake.
>>>>
>>>> The only thing I do different in practice is, I first tune for max 
>>>> smoke
>>>> with about 30w of drive, just to get everything in resonance, then I
>>>> proceed
>>>> as described above.
>>>>
>>>> Dip?  40 years ago, maybe!
>>>>
>>>> 73 - Rick, DJ0IP
>>>> (Nr. Frankfurt am Main)
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Bob
>>>> McGraw
>>>> - K4TAX
>>>> Sent: Saturday, March 01, 2014 10:00 PM
>>>> To: Discussion of Ten-Tec Equipment
>>>> Subject: Re: [TenTec] In praise of older technology
>>>>
>>>> The only thing I ever "dip" is a little chew.
>>>>
>>>> 73
>>>> Bob,  K4TAX
>>>>
>>>>
>>>> ----- Original Message ----- From: "Brian Carling" 
>>>> <bcarling at cfl.rr.com>
>>>> To: "Ed Purvis" <wa4njy at yahoo.com>; "Discussion of Ten-Tec Equipment"
>>>> <tentec at contesting.com>
>>>> Sent: Saturday, March 01, 2014 2:18 PM
>>>> Subject: Re: [TenTec] In praise of older technology
>>>>
>>>>
>>>>> Ed you must be talking about those XE stations tuning up on SSB on the
>>>>> low
>>>>
>>>>> end of 40m. They groan "hoooooo-la" while they dip the plate control !
>>>>> SOP
>>>>>
>>>>> Best regards - Bry Carling
>>>>>
>>>>>
>>>>>
>>>>>> On Feb 22, 2014, at 8:29 PM, Ed Purvis <wa4njy at yahoo.com> wrote:
>>>>>>
>>>>>> There are some on hi-fi sideband that I am not sure they are talking
>>>>>> or
>>>>>> their stomach is making noise.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ________________________________
>>>>>> From: Steve Berg <wa9jml at frontier.com>
>>>>>> To: Discussion of Ten-Tec Equipment <tentec at contesting.com>
>>>>>> Sent: Saturday, February 22, 2014 8:12 PM
>>>>>> Subject: Re: [TenTec] In praise of older technology
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> As part of my collection, I have Drake 2B receiver and a Gonset 
>>>>>> GSB100
>>>>>> phasing exciter.  One night I wound up in a round table with a bunch
>>>>>> of
>>>>>> HiFi SSB aficionados 0n 40 meters.  These guys were running advanced
>>>>>> equalizers and high-end microphones. Then had the latest Oriental
>>>>>> Transceivers. They even had audio spectrum analyzers to check out 
>>>>>> each
>>>>>> others signals.  So, I asked for an evaluation, and they were quite
>>>>>> complimentary.  So, they asked what I was running, and I told them a
>>>>>> 1957 vintage phasing exciter with a D104 mic.  They were amazed!
>>>>>> Sure,
>>>>>> it drifts, and it is hard to get it right on frequency by zerobeating
>>>>>> the receiver BFO with the carrier on the exciter.  But it is a lot of
>>>>>> fun to use.
>>>>>>
>>>>>> Steve WA9JML
>>>>>>
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>>>>
>>>>
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>>>
>>>
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>>
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