[TenTec] 318 and qsk-5

Sat Dec 7 08:27:53 EST 2013

To touch on the point, unless the Thunderbolt has been modified, there is no 
switching or relays inside the amp.  The input connector goes direct to the 
input selector switch which then goes to the input network and then the 
grids of the 4-400 tubes.  The output of the Pi network is connected direct 
to the output coax connector.  At the right rear of the amp is a 4 pin 
connector.  The pins are ground, operate bias, standby bias and grid.  To 
switch from standby to operate the correct bias voltage much be switched to 
the grid terminal.  The VR regulators are for the screen voltage and the 
bias voltage.

To configure the amp for QSK, one will need to provide a means to switch RF 
at the input and output of the amp and a means to simultaneously switch the 
bias from standby to operate.  I am not aware of any commercial product that 
will accomplish this task.  Thus expect to "roll your own" switching system.

Operating in Class AB2 mode, the input circuit is a tuned input and thus the 
drive power for rated output is in the order of 2 watts.  In the LINEAR mode 
the input is swamped by a big resistor and one can expect required drive to 
be about 30 watts or so.

The Johnson Thunderbolt was designed and sold in the 1960's and was used for 
SSB and AM.  I don't recall we even knew what QSK was during that time 
period.  Later Johnson came out with an "electronic" T/R switch.  These were 
found to be mostly monster TVI generators as the switching tube was driven 
into a gross area of non linearity.

Although this amp is a very well built amp and will run for days in a 
key-down mode, they weight in at some 135 lbs. The HV transformer in a full 
wave CT configuration, the swinging filter choke and the low voltage 
transformer and filter choke adds some serious iron to this amp.   Power 
output is in the area of 600 to 750 watts.  Remember, this amp was designed 
when the "legal limit" was 1 KW DC input.  The meter scale is so calibrated 
as well.

I just completed a re-furbish job on one of these.  If they are used as 
designed, they will produce some of the cleanest RF of any amp on the market 
today.  They are great and one won't need to worry about the desk moving 
around when sending aggressive CW.

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, December 07, 2013 2:10 AM
Subject: Re: [TenTec] 318 and qsk-5

> GM Mike,
>
> I think I will pass on this one.
> This is not going to be a PLUG'n'Play solution.
>
>  Bob seems to know them.
> I 'remember' seeing them when I was a kid, but I left the states soon 
> after
> that and never saw one again.
>
> In general, if you want to run QSK with a NON-QSK Amp, you will need the
> QSK5.
>
> The Model 318 has no way to speed up switching inside the amplifier.
> It just slows down the switching when returning to RX mode, to PREVENT the
> amp from "trying" to follow the QSK switching.
>
> In other words, the Model 318 enables "Clean Semi-BK", but with a caveat.
> The amp's relay can't be too big and clunky.  If so, it won't be happy 
> with
> the 15mS pre-dit time which is a fixed value coming from the Orion.  For 
> the
> Eagle, it's 17mS.
>
> TEN-TEC, PLEASE INCREASE THIS TO "20Ms" or better yet, "22mS", AND THEN IT
> WILL WORK WITH JUST ABOUT ANYTHING!
> NOTE: the specs on most open frame relays are something like 15 to 20 mS
> switching plus 1 to 2 mS settling time, depending on make and model.
>
> The QSK-5 actually does enable QSK switching, at least with most amps, but
> in the case of the Thunderbolt, you will need to add additional hardware.
> By the time you do all that, it may have been just as easy to pick up a
> second, used amp.
>
> 73
> Rick, DJ0IP
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Michael
> Tortorella
> Sent: Saturday, December 07, 2013 12:37 AM
> To: 'Discussion of Ten-Tec Equipment'
> Subject: Re: [TenTec] 318 and qsk-5
>
> Hi Rick, sorry, I forgot to include that the rigs are Corsair II and 
> Johnson
> Courier or Thunderbolt.  Was hoping to use the amp with QSK.
> 73
> Mike
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Rick -
> DJ0IP / NJ0IP
> Sent: Friday, December 06, 2013 4:23 PM
> To: 'Discussion of Ten-Tec Equipment'
> Subject: Re: [TenTec] 318 and qsk-5
>
> Mike, these are two totally different animals.
> The QSK-5 speeds up the amp switching, while the 318 slows it down.
> Both solutions can work, but it also depends a bit on the amp and how fast
> its relay switches.
> What rig and amp are you trying to mate.
>
> 73
> Rick, DJ0IP
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Michael
> Tortorella
> Sent: Friday, December 06, 2013 6:32 PM
> To: 'Discussion of Ten-Tec Equipment'
> Subject: [TenTec] 318 and qsk-5
>
> Tentec friends, I am looking for help comparing the TenTec 318 with the
> Ameritron QSK-5.  Has anyone used either/both of these who could offer 
> some
> insights?
>
> Thanks and 73
>
> Mike W2IY
>
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