[time-nuts] Question about FTS 1050A

Robert Darby bobdarby at triad.rr.com
Thu Apr 4 02:21:32 UTC 2013


A little follow-up.

I looked at all four 1000B outputs with the scope; one pair is at 1.2V 
rms and the second is at .7V rms.  The waveform looks clean and is close 
to the 1.0V and .5V described on the spec sheet so I conclude that the 
oscillator is fine.

I disassembled the doubler case to check the voltage there and found 
that the voltage regulator is working correctly. There are two identical 
boards inside. The oscillator feeds a Mini-Circuits AK-2(+) frequency 
multiplier directly and each doubled output is fed into two identical 
circuits each with with 4 2n2222's, two diodes, assorted resistors and 
caps thence out through a Mini-Circuits wideband transformer TMO4-6.  
With the boards on the bench I jury rigged an oscillator to drive the 
input and I get the same low output, albeit rather cleaner.  I'm going 
to order some connectors so I can be certain about the signal path and 
check the doublers again.

  I wonder if someone needed four low level 10MHz outputs and 
ordered/modified the amplifiers to suit.  I'm not sure they're working 
perfectly but I suspect most of the noise I'm seeing is due to my 
hook-up to the tnc connectors.  I'll know more once I get some 
connectors and meanwhile I'll attempt to draw a schematic of the circuit.

Thanks for everyone's comments; more later.

Bob Darby

On 4/3/2013 6:35 PM, paul swed wrote:
> Bob I have no schematics but some pics might be helpful in trying to
> understand why the 7818 has not incoming voltage. I speculate the unit plus
> into 110 VAC?
> The TNCs almost make sound like some cel tower thing.
> Regards]
> Paul
> WB8TSL
>
>
> On Wed, Apr 3, 2013 at 3:07 PM, Tom Knox<actast at hotmail.com>  wrote:
>
>> Hi Bob;
>> I was wondering who won the unit. They are very nice oscillators. With
>> noise on older equipment like the 1050A I would check  and/or replace caps.
>> I am about to do that to my own 1050A. It may not resolve the problem, but
>> it will eliminate that possibility. I look forward to hearing how the
>> problem is resolved.
>> Best Wishes;
>> Thomas Knox
>>
>>
>>
>>> Date: Wed, 3 Apr 2013 14:53:55 -0400
>>> From:bobdarby at triad.rr.com
>>> To:time-nuts at febo.com
>>> Subject: [time-nuts] Question about FTS 1050A
>>>
>>> I purchased an FTS 1050 recently and after a cursory inspection of the
>>> interior powered it up to see if it's functional.
>>>
>>> This particular unit is a bit odd; it has the optional battery back-up,
>>> no PPS, and instead of the usual 1Mhz, 5Mhz, 10Mhz it has four 10Mhz
>>> outputs with tnc female connectors.
>>>
>>> The tnc connectors are a bit of a bother but I found that the scope
>>> probe sleeve that fits a bnc also fits into a tnc so I'm able to view
>>> the outputs.  They are not pretty, lots of hash, particularly at the
>>> zero crossings and only about 15 to 20mV rms.  That's the case for all
>> four.
>>> The oscillator is an FTS 1000B-503 which is supposed to have four
>>> buffered outputs at 5MHz; two at 1.0 V rms and two at 0.5 V rms. Two
>>> outputs each drive a pair of frequency doublers that thus provide the
>>> four 10Mhz outputs.  I got a connector on one of the spare outputs to
>>> see if the problem might lie in the oscillator. What I see there is a
>>> very stable clean sine wave at 5MHz at about 660mV rms so I'm assuming
>>> the 1000B is not my problem.
>>>
>>> The doublers are housed in a tidy box adjacent to the oscillator with
>>> 22V and ground, two 5MHz inputs and four 10MHz outputs all in the top
>>> cover.  There is a stone cold 7818 in a TO-3 metal can mounted on one
>>> side of the box but no external connections other than those previously
>>> noted.  It seems to me my problem must lie in this area and, since all
>>> four circuits are similarly affected, is probably related to the power
>>> supply housed therein.
>>>
>>> This is probably obvious to all of you but I'm a toolmaker by trade so
>>> this is all new to me and second opinions will not hurt my feelings.
>>> Also does anyone have any experience inside of the doubler box or a
>>> schematic of the standard (or any other version) doubler/divider for
>>> these things?
>>>
>>> Thanks for any insight anyone can offer.
>>>
>>> Bob Darby
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