[Boatanchors] Need suggestions and question on antenna for DX-100

[Rodger]

Hi Glen,

I agree that 125 is a bit optimistic but that is straight from Heathkit's
specifications for the DX-100.  In any case, the point remains that be
careful using smaller modern antenna tuners with these high level AM rigs.

Of course if you reduce the input to increase tube life (not a bad thing to
do!) be sure and also reduce modulator power accordingly

Rodger WQ9E

> -----Original Message-----
> From: Glen Zook [mailto:gzook at yahoo.com]
> Sent: Sunday, February 18, 2007 1:41 PM
> To: Rodger; boatanchors at mailman.qth.net
> Subject: RE: [Boatanchors] Need suggestions and question on antenna for
> DX-100
> 
> If you are getting 125 watts carrier output on the
> DX-100 on AM carrier you are really overloading the
> final amplifier tubes!
> 
> The 6146 and 6146A/8298 are rated at 67.5 watts
> maximum INPUT on AM each, this per the RCA
> specifications.  That means a total MAXIMUM INPUT
> power of 135 watts for the DX-100.  With the usual
> about 60% efficiency this would mean about 80 watts
> output on 80 meters.  This efficiency drops off with
> being around 50% on 10 meters.  This means about 68
> watts output on 10 meters.
> 
> The 6146B/8298A and any 6146W with a code date of 1965
> or after is rated at 90 watts INPUT on AM.  However,
> using the 6146B/8298A in the DX-100 often results in
> all sorts of problems.  Thus, use of that series of
> tubes is generally discouraged in the DX-100 /
> DX-100B.
> 
> For the article on the 6146 family of tubes that
> appeared in Electric Radio (and has been reprinted in
> several other publications) a while back go to the
> K9STH website (URL listed at the end of this message).
>  Choose the K9STH link from the home page and then the
> article is in another link on that page.
> 
> If you cut the INPUT power on the DX-100 back to
> around 100 watts on AM the station at the other end is
> not going to know the difference.  However, your final
> amplifier tubes are going to last several times longer
> than when running at the 135 watt INPUT level.  If you
> run more power INPUT than 135 watts on AM then your
> final amplifier tube life is going to be greatly
> reduced, sometimes by a factor of 10 or even greater.
> 
> 100 watts input is going to mean around 60 watts
> output on 80 meters (a little more with new tubes) and
> around 50 watts output on 10 meters.
> 
> Glen, K9STH
> 
> 
> --- Rodger <WQ9E at dtnspeed.net> wrote:
> 
> Keep in mind that high level AM puts much more stress
> on antenna tuners than SSB or CW so the lower power
> MFJ and similar tuners are not advisable.  Operating
> AM, the DX-100 will produce around 125 watts
> continuous carrier output which increases to 500 watts
> on modulation peaks.  Thus the tuner gets a continuous
> heating workout from the carrier and gets "tested" for
> flashover on modulation peaks.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Glen, K9STH
> 
> Website:  http://k9sth.com
> 
> 
> 
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