[TenTec] In praise of older technology

Sat Mar 1 22:02:50 EST 2014

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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