[Amps] SB-220 HV Transformer Wanted ; thread stolen for bias question

Mon Nov 4 01:52:20 EST 2019

My opinion:
In the  "old days" we were expected to tune into a dummy load and match 
the antenna with a tuner using low power as we are today

The big Henry amps were usually run well beyond the legal limit, so 
tuning beyond a KW was no different than running 3 to 5 KW SSB, or CW. 
The difference in "those days" was the FCC enforced the rules so you 
generally needed to be much more careful when running your California KW.
Of course with today's VNAs it's quite easy to get the SWR right down to 
1:1 so tuning into a DL and then switching to the antenna requires no 
peaking. If everything is matched and the signal is clean, "GENERALLY" 
no one bothers you unless the signal is obnoxiously strong and creates 
problems.for others. I don't believe the FCC has the manpower now days 
to go after anyone except the really bad apples.  If you read the FCC 
actions, they typically are for hams who are causing malicious 
interference.  In those cases power may be mentioned..

The knowledge level on the bands is abysmal. It reminds me of when 
working as a GA for my masters. I was teaching the intro to Computer 
Science to 5 classes with a max of 40 per class. I had a total of 195 
students.  This was for non CS students. Mostly business majors.
I had around 5 ot 10 who weren't going to make it.  I had another 5 or 
10 who were at, or above my level. IOW, for them it was a "blow off" 
class, but in general the knowledgeable level in there was abysmal too.

I spend a lot of time on FB, helping new hams.  With the new testing, 
they have no technical knowledge.  Virtually none!
Typically the old timers are merciless and when they do try to help, the 
new hams knowing nothing get angry because they think they are being 
talked down to.

The gap in technical knowledge is tremendous so explaining to these new 
hams using the technical language is a lost cause and having taught to 
this level, I can understand why they feel snowed under and talked down 
to.and why there is so much animosity.

73, Roger (K8RI)

On 10/31/2019 9:30 AM, Mark Bitterlich wrote:
> Hi Gary, thanks for your reply.
>
> Yes, I was around when regulations were based on input power (1968) and have
> heard your explanation before but I tend to question it simply because the
> Henry 3K and 8K series of amps also came stock with the CW/SSB selection and
> either of those two could easily exceed 1000 watts DC input in the CW
> position.  FSK and AM modes were also advised to use CW and not SSB modes
> possibly with plate dissipation limits in mind as well as legal issues of
> input power.
>
> But based on the typical pair of 3-500's say in the 3K original designs, in
> CW mode idling current was 90-120 ma, and in the higher plate voltage SSB
> position  170-220 ma.
>
> My logic was simply:
>
> Bias controls the class of amplifier.
> A change in bias means the class of amplification must have also changed.
> Switching from CW to SSB causes an indicated bias change from 120 ma to 220
> ma.
> The impact of a bias change of  120 to 220 ma would lead me to believe that
> the class of amplifier shifted slightly in a more linear direction with also
> the result of slightly lower efficiency.
>
> Right or wrong or maybe just trivial ...  if wrong could you please explain
> your logic?
>
> Mark
> Wa3jpy
>
> -----Original Message-----
> From: Gary Schafer [mailto:garyschafer at largeriver.net]
> Sent: Wednesday, October 30, 2019 10:13 PM
> To: 'mark bitterlich'; 'Joe Subich, W4TV'; 'Joe'; amps at contesting.com
> Subject: RE: [Amps] SB-220 HV Transformer Wanted
>
> No. The amp runs AB2 meaning it draws grid current.
>
> The reason for the CW/SSB switch was to allow tune up at 1 KW DC input on
> CW.
> This was the regulation at the time the amp was designed. You were not
> allowed to ever exceed 1 KW DC input, even during tune up.
> Switching to SSB after CW tune up allowed higher PEP input by maintaining
> the same plate load impedance (where the amp was tuned)for the higher power.
> In other words the voltage to current ratio remained the same when the
> higher voltage was selected.
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of mark
>> bitterlich
>> Sent: Wednesday, October 30, 2019 4:23 PM
>> To: Joe Subich, W4TV; Joe; amps at contesting.com
>> Subject: Re: [Amps] SB-220 HV Transformer Wanted
>>
>> Ok, this brings up a technical question that pertains to the topic
>> amazingly enough. When you shift from single sideband to CW on this amp
>> are you or are you not moving the class of operation from AB1 towards
>> AB2 and thus  improving efficiency?MarkWA3JPY
>
>
>> -------- Original message --------From: "Joe Subich, W4TV"
>> <lists at subich.com> Date: 10/30/19  16:36  (GMT-05:00) To: Joe
>> <nss at mwt.net>, amps at contesting.com Subject: Re: [Amps] SB-220 HV
>> Transformer Wanted On 2019-10-30 3:12 PM, Joe wrote: > Why need
>> them?Some people prefer to keep their equipment "stock" or at
>> leastfunctionally stock.  The SB-200 was never designed for 1500Woutput
>> on CW - it was designed to operate at 1 KW DC input (ca.700 W CW or 1500
>> W PEP SSB output).Pushing the SB-220 to 1500 W CW output (or worse,
>> running RTTYon the high taps) is a quick way to fry something.  Even
>> thetoroidal transformer you recommend is only rated for 800 W!73,    ...
>> Joe, W4TVOn 2019-10-30 3:12 PM, Joe wrote:> Why need them?> > Run it at
>> the HV side and use less drive and less currents all around.> > The
>> CW/SSB switch I converted into a stand-by switch.> > Joe WB9SBD> Sig>
>> The Original Rolling Ball Clock> Idle Tyme> Idle-Tyme.com>
>> http://www.idle-tyme.com> On 10/30/2019 1:38 PM, Joe Subich, W4TV
>> wrote:>>>> >> https://www.antekinc.com/as-8t800-800va-transformer/>>>>
>> Unfortunately, this transformer lacks the primary taps for CW/SSB>>
>> operation of the OEM device.>>>> 73,>>>>    ... Joe, W4TV>>>>>> On 2019-
>> 10-30 10:23 AM, Joe wrote:>>>>>> On 10/30/2019 8:56 AM, Joe wrote:>>>>
>> Morning Dick,>>>> If you are not afraid of making a few electrical and
>> mechanical >>>> modifications, I would go with this transformer.>>>>
>> https://www.antekinc.com/as-8t800-800va-transformer/>>>>>>>> I'm glad I
>> did! 1/4 the cost of most drop in replacements. yet MUCH >>>> better
>> performance!>>>> Joe WB9SBD>>>>>>
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-- 
Roger (K8RI)