[TenTec] In praise of older technology

[Kim Elmore]

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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