The Japanese model of the TL-922 does not go into the SSB Hi voltage mode. If
you want more power out of it you need to go in and connect up the HI tap on
the transformer. I ran into this probolem and it was then I relaized it was a
Jap model. Check tha out and see. Maybe someone already did it.
It is a Japanese model -- you can set it up for 200-240 V but not 120, and
> it came with 10 meters installed. I wonder if they are different in any
> other way?
-----Original Message-----
From: Carl <km1h@jeremy.mv.com>
To: Vic Rosenthal <k2vco.vic@gmail.com>; amps <amps@contesting.com>
Sent: Tue, Mar 11, 2014 1:23 pm
Subject: Re: [Amps] Pi-L Network Question
All TL-922's are that way since the JA's did not have the low end of the
band when built. I started working them up around 1970 if I remember in the
80's.
Carl
KM1H
----- Original Message -----
From: "Vic Rosenthal" <k2vco.vic@gmail.com>
To: <amps@contesting.com>
Sent: Tuesday, March 11, 2014 12:59 PM
Subject: Re: [Amps] Pi-L Network Question
> The TL922 I have would not load properly at 1810 kHz without adding
> capacity. Although now it works, it is less efficient than on other bands
> and it probably should have more inductance. I couldn't find an easy way
> to do this neatly, so I left it alone. I suspect it was designed for 1.9
> mHz.
>
> It is a Japanese model -- you can set it up for 200-240 V but not 120, and
> it came with 10 meters installed. I wonder if they are different in any
> other way?
>
> On 3/11/2014 9:33 AM, Carl wrote:
>> Add a carbon pot at the anode end and feed an antenna analyzer into the
>> output connector. Find out what the difference is between calculated and
>> tested and do the math to find the K factor used.
>>
>> Ive often found even commercial amps to be shy on the 160 and 80M load C
>> especially when a lot of fixed C is used and the measured C is well on
>> the low side of what is printed.
>>
>> One amp that is shy on 160M C and L is the Clipperton L and its variants.
>>
>> The SB-200 is also low on C at the low end of 80 with a typical antenna.
>>
>> For my own amps I modify and make the pi network load the various160 and
>> 80M antennas since some have a high VSWR at places and I refuse to waste
>> money on an external tuner. Ive been doing that since the 60's.
>>
>> Carl
>> KM1H
>>
>> ----- Original Message ----- From: "Jim Garland" <4cx250b@miamioh.edu>
>> To: <amps@contesting.com>
>> Sent: Tuesday, March 11, 2014 11:44 AM
>> Subject: [Amps] Pi-L Network Question
>>
>>
>>> Hi all, I've built a tank circuit using the on-line Pi-L network
>>> calculators by VE3OZZ and also G3SEK. These are both based on the
>>> equations
>>> published in an article in August 1983 QST (by W5FD). Althought the
>>> G3SEK
>>> calculator is somewhat more sophisticated (it corrects for tube and
>>> stray
>>> inductances and capacitances), both calculators give about the same
>>> answers
>>> for 80m and 160m. I'm finding that the predicted values for C1 and L1
>>> are
>>> very close to what I need to tune the amplifier, but the predicted
>>> values of
>>> C2 are far lower than what is required to load the amplifier properly.
>>> I'm
>>> wondering if there could be an error in the W5FD formulas, and if anyone
>>> else has experienced the same problem? (If there is an error, it
>>> probably
>>> wouldn't be noticed on the higher frequency bands, because the load cap
>>> would most likely have enough tuning range to compensate for the error.)
>>>
>>>
>>>
>>> I've computed the Pi-L network values over a range of plate
>>> impedances. (My
>>> amp uses bandswitched L1 and L2, so those values don't change.) What I
>>> find
>>> is that as the plate impedance increases (e.g., tuning the amp at a
>>> lower
>>> power level), the equations predict that Q goes from 10 to 18, C1
>>> doesn't
>>> change, C2 increases only about 5 percent. In other words, according
>>> to the
>>> on-line calculators, tuning to a lower power requires a minor tweaking
>>> of
>>> the load capacitance, but that's all
>>>
>>>
>>>
>>> At 3.5 MHz, for my amp, the equations predict a load capacitance of
>>> 1057 pF
>>> and on 1.8 MHz, a load capacitance of 2057 pF. I'm finding that, in
>>> practice, those predicted values are more than 1000pF too low.
>>>
>>>
>>>
>>> Here are some details of the actual tank circuit:
>>>
>>> The design plate impedance is nominally 720 ohms (2500V@2.0A, with
>>> k=1.7)
>>> <mailto:2500V@2.0A,%20with%20k=1.7)> , Q=10, and I've computed network
>>> values for a range of plate impedances from 720 to 1440 homs. The actual
>>> tank circuit is:
>>>
>>> 80m: L1=8.4 uH, L2=3.8 uH
>>>
>>> 160m: L1=16.3uH, L2=7.4uH
>>>
>>>
>>>
>>> I'm using two paralleled 1000pF doorknobs for a plate blocking
>>> capacitance.
>>> The plate choke is 225 uH, bypassed at the base by 7700 pF. The safety
>>> RF
>>> choke is 470uH, with an 18 ohm DC resistance. The tune and load caps
>>> are
>>> 30-240pF and 33-1000pF air variables padded with doorknobs, as required.
>>>
>>>
>>>
>>> The tank seems to tune smoothly, with no heating or quirkiness. THe only
>>> problem is that I need much more C2 capacitance than the formulas
>>> predict.
>>> At this point, I'm at a loss to explain the discrepancy, other than
>>> wondering if there's an error in the formulas somewhere.
>>>
>>>
>>>
>>> 73,
>>>
>>> Jim W8ZR
>>>
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>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
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>>
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>
> --
> Vic
> _______________________________________________
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>
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