[Amps] Amps Digest, Vol 173, Issue 56

Tue May 23 11:24:19 EDT 2017

I used this trick on my Dual 4-1000 amplifier. Power and Efficiency 
jumped way up on 10 and 15 meters with a home made inductor. I made the 
inductor out of flat stock and it was right at the tubes before the Cap.

C

On 5/23/2017 5:55 AM, amps-request at contesting.com wrote:
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> Today's Topics:
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>     1. Re: Henry 3 KD Premier with 8877 (MU 4CX250B)
>     2. Re: new amp race (donroden at hiwaay.net)
>     3. new amp race / antenna take-off angle (Jim Thomson)
>     4. Re: new amp race / antenna take-off angle (Alek Petkovic)
>     5. Re: new amp race / antenna take-off angle (Martin Sole)
>     6. new amp race (Jim Thomson)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 22 May 2017 15:53:24 -0600
> From: MU 4CX250B <4cx250b at miamioh.edu>
> To: TexasRF at aol.com
> Cc: "jmiklos at windstream.net" <jmiklos at windstream.net>,
> 	"amps at contesting.com" <amps at contesting.com>
> Subject: Re: [Amps] Henry 3 KD Premier with 8877
> Message-ID: <1705483551472352915 at unknownmsgid>
> Content-Type: text/plain; charset="UTF-8"
>
> I'm not familiar with that particular amplifier, but low 10m
> efficiency is a common problem with 8877 amplifiers. In one of my
> homebrew amplifiers, I had low efficiency in the 40% range until,
> following a suggestion from Bob Sutherland W6PO, I relocated the tuned
> pi input circuit capacitor C2 from the input band switch directly to
> the cathode pin on the tube. Incredibly, efficiency jumped up into the
> 60% range. I was dumbfounded.
> 73,
> Jim w8zr
>
> Sent from my iPhone
>
>> On May 22, 2017, at 3:45 PM, Gerald Williamson via Amps <amps at contesting.com> wrote:
>>
>> Going back to the fundamentals: overall efficiency for class AB2 is
>> approximately .65 times (Qu - Ql) divided by Qu. Qu is unloaded Q and Ql is
>> loaded Q.
>>
>> at 10m the Qu is higher because inductor losses are higher. In addition,
>> part of the inductance includes band switch leads and other leads between
>> tank  circuit components. These leads are typically smaller causing losses to
>> increase. In addition, tune C has a minimum value that adds to the total C
>> and  that increases the loaded Q which further increases losses.
>>
>> Gerald K5GW
>>
>>
>>
>>
>>
>> In a message dated 5/22/2017 4:14:25 P.M. Central Daylight Time,
>> jmiklos at windstream.net writes:
>>
>> Does  anyone have any first hand experience with this amplifier?  I?m
>> particularly interested in the 10 meter performance (Eb, Ib, Pi, Po).   Maximum
>> power output at .9A of Ib is only 1200 watts with efficiency at  43%.  The
>> lower frequencies are more typical for an 8877, ie, 1500 watts  out with
>> efficiency around 64% and Ib at .75A.  Any theories to explain  the low
>> efficiency on 10?
>>
>> 73?s
>> Buzz
>>
>> Buzz Miklos  WA4GPM
>> 2043 Hawkcrest Drive E
>> Saint Johns, FL  32259
>> 570-974-7433
>> _______________________________________________
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> ------------------------------
>
> Message: 2
> Date: Mon, 22 May 2017 18:50:08 -0500
> From: donroden at hiwaay.net
> To: amps at contesting.com
> Subject: Re: [Amps] new amp race
> Message-ID:
> 	<20170522185008.Horde.qgk9Lkyai5-DvV8HCgfEqEE at webmail.hiwaay.net>
> Content-Type: text/plain; charset=utf-8; format=flowed; DelSp=Yes
>
>
> Quoting donroden <donroden at hiwaay.net>:
>
>> Bought a WSPRLite transmitter... amazing to see vk and zl reporting
>> way above noise using 50 mw....Yes 1/5 of a watt.
> For you math majors that let this slip by, 50mw is 1/20th of a watt...
> On the way to work today, I realized my mistake.
>
> Don W4DNR
>
>
> DonR
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 23 May 2017 05:01:06 -0700
> From: "Jim Thomson" <jim.thom at telus.net>
> To: <amps at contesting.com>
> Subject: [Amps] new amp race / antenna take-off angle
> Message-ID: <442DCCB15873408CA16E83805473823E at JimPC>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> Date: Sun, 21 May 2017 19:14:09 +0930
> From: "Leigh Turner" <invertech at frontierisp.net.au>
> To: "'AMPS'" <amps at contesting.com>
> Subject: Re: [Amps] new amp race / antenna take-off angle
>
> <Precisely correct Peter!
>
> If the HF antenna lobe take-off angle is fortuitously optimal for enabling a
> given DX hop path then QRP Tx power will wing it!
>
> No amount of Tx power or Rx sensitivity / SNR will compensate if this sweet
> spot in the prevailing ephemeral propagation path is missed...
>
> 73
>
> Leigh
> VK5KLT
>
> ##  Both VK land + germany have  a 10 meter...  aka 33 foot height limit.  That now effectively
> just destroyed amateur radio.  I dont know what take off angle  you are blathering  on about leigh.
> At just 33 ft  with your height restriction.... the only angle you are  gonna have is either straight up...
> or into the side of you neigbours home.   33  ft will not clear anything, and is  100%  ineffective.
> Utility poles around  na are  typ 40 ft high,  with  the hv wire another 1.5 ft above that.   The typ home,
> with its well grounded chicken mesh, just beneath the stucco.  Toss in your  400  watt useless ..legal
> limit, and you are doomed to failure.
>
> Jim  VE7RF
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 23 May 2017 20:20:50 +0800
> From: Alek Petkovic <vk6apk at bigpond.com>
> To: AMPS <amps at contesting.com>
> Subject: Re: [Amps] new amp race / antenna take-off angle
> Message-ID: <59242922.4020206 at bigpond.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Not in this part of there world, there ain't no 10m limit.
>
> Most suburban masts are around 15m to 20m high. All applications are
> assessed on an individual basis. There are moves afoot to have a 10m
> minimum ratified across the country but that has not happened yet. If it
> does, it means, you will not have to ask for permission to put up a mast
> of that height. Anything bigger, you'll have to ask.
>
> Of course, in rural areas, the sky is the limit.
>
> 73, Alek.
> VK6APK
>
> On 23/05/2017 8:01 PM, Jim Thomson wrote:
>> Date: Sun, 21 May 2017 19:14:09 +0930
>> From: "Leigh Turner"<invertech at frontierisp.net.au>
>> To: "'AMPS'"<amps at contesting.com>
>> Subject: Re: [Amps] new amp race / antenna take-off angle
>>
>> <Precisely correct Peter!
>>
>> If the HF antenna lobe take-off angle is fortuitously optimal for enabling a
>> given DX hop path then QRP Tx power will wing it!
>>
>> No amount of Tx power or Rx sensitivity / SNR will compensate if this sweet
>> spot in the prevailing ephemeral propagation path is missed...
>>
>> 73
>>
>> Leigh
>> VK5KLT
>>
>> ##  Both VK land + germany have  a 10 meter...  aka 33 foot height limit.  That now effectively
>> just destroyed amateur radio.  I dont know what take off angle  you are blathering  on about leigh.
>> At just 33 ft  with your height restriction.... the only angle you are  gonna have is either straight up...
>> or into the side of you neigbours home.   33  ft will not clear anything, and is  100%  ineffective.
>> Utility poles around  na are  typ 40 ft high,  with  the hv wire another 1.5 ft above that.   The typ home,
>> with its well grounded chicken mesh, just beneath the stucco.  Toss in your  400  watt useless ..legal
>> limit, and you are doomed to failure.
>>
>> Jim  VE7RF
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>>     