Topband: DX-100 adventure contiunued

Charlie Cunningham charlie-cunningham at
Wed Jan 8 16:06:48 EST 2014

Hi,  Bruce

Well, I agree. And if I follow your reasoning, it doesn't take much of an
increase in line voltage to push the HV from 825 VDC to over 900 VDC., as
Bill observe. Might be the choke, but I'd be really surprised at the entire
winding being shorted. I'd surely want to start by measuring line voltage
before digging into details like looking for a "shorted" choke!

Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at] On Behalf Of Bruce
Sent: Wednesday, January 08, 2014 3:51 PM
To: Charlie Cunningham; 'Bill Cromwell'
Cc: 'topband'
Subject: Topband: DX-100 adventure contiunued

Hi Charlie,

A little cross multiplication shows that if you had 600 volts when the 
primary is 110 VAC,   then with 130 primary volts you should have 709 Volts.

A larger increase takes place between choke input and  capacitor input. 
(depends upon the size of the capacitor)   Most likely a shorted choke or a 
miswiring problem. (Was the transmitter a kit?)  Best to check the choke
Does both ends of the choke have the same resistance back to the rectifier
filament connection ?  You should see the choke resistance as a difference.


----- Original Message -----
From: "Charlie Cunningham" <charlie-cunningham at>
To: "'Bill Cromwell'" <wrcromwell at>
Cc: "'topband'" <topband at>; "'Tom W8JI'" <w8ji at>
Sent: Wednesday, January 08, 2014 3:14 PM
Subject: Re: Topband: DX-100 adventure contiunued

> Hi, Bill
> Well, I suspect that the light bulbs may be a "tip-off". The do make 130
> volt bulbs for folks with line voltage that runs a bit high, but that
> doesn't help you DX-100 or other appliances. Sounds like you need to get
> you power provider to look into  you line voltage and regulation. Also, if
> they have power-factor correction capacitors connected on those 
> distribution
> feeders in the winter-time when the power factor is less inductive and
> closer to unity, that can result in soe increase in line voltage in the
> winter time. GL!
> 73,
> Charlie, K4OTV
> -----Original Message-----
> From: Bill Cromwell [mailto:wrcromwell at]
> Sent: Wednesday, January 08, 2014 2:45 PM
> To: Charlie Cunningham
> Cc: 'Tom W8JI'; 'topband'
> Subject: Re: Topband: DX-100 adventure contiunued
> On 01/08/2014 01:36 PM, Charlie Cunningham wrote:
>> Hi, Bill
>> I was also going to ask if you have a choke input filter -or if you could
>> change the PS filter configuration to choke input to help a bit with the
> HV.
>> Also, check your line voltage - especially at night when the load on the
>> electric grid drops. I've seen my 240 VAC  here get up well past 265 
>> volts
>> at night! Use a trusted, well calibrated volt meter and take some voltage
>> readings at different  times of day to get a feel for what the line
>> regulation looks like!  Note that a 10 % increase in line voltage would
>> increase that HV from 825  VDC to over 900 VDC.  10 % high line is not
>> really unusual.  Finally, you can check with your local PUC - there are
>> regulatory limits to how much the AC line is permitted to vary - but I'd
>> start with the power provider first. Maybe they need to drop your
>> distribution feeder down a tap at the substation. Excessive voltage is
> hard
>> on lots of things around your house besides DX-100s! The utility can cme
> out
>> and put a recording voltmeter on your line for a while to see what's 
>> going
>> on, if you complain about excessive line voltage.
>> GL!
>> 73,
>> Charlie, K4OTV
> Hi Charlie,
> The DX-100 High voltage is choke input by design. I changed the low
> voltage supply to choke input as well and the rf stages are behaving
> very nicely with that. I already think my line is "high" and I'll take
> readings various times as you have suggested. Light bulbs don't seem to
> last very long here, either.
> Tom asked about bleeder current. I didn't try to measure it but I
> watched the high voltage decay to zero in a very few seconds when I
> switched it off with no 6146s in the sockets.
> 73,
> Bill  KU8H
> _________________
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