> This is just a free running PRS10 wired to a TAPR TICC, I thought that I would
> run some stand alone tests before I brought my GPSDO in line too.
Ok, good idea to do a stand alone test. The plateau, though, is interesting and
I wouldn't quite have expected that in a 1PPS vs 10 MHz self-test.
- Original Message -
From: "jimlux"
To:
Sent: Sunday, October 14, 2018 7:07 PM
Subject: Re: [time-nuts] Troubleshooting an HP 58503A
On 10/14/18 3:03 PM, Matthew D'Asaro wrote:
All -
Thanks again for all the suggestions and advice I have gotten on this
project. It ran all
On 10/14/18 3:03 PM, Matthew D'Asaro wrote:
All -
Thanks again for all the suggestions and advice I have gotten on
this project. It ran all night without loosing lock, so I am calling it
fixed. There is just one more order of business before I can use it, and
that is some way of
Am 14.10.2018 um 22:14 schrieb Richard (Rick) Karlquist:
On 10/14/2018 11:20 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
Actually the BFT is out of production since quite a while there are
more stable and higher Ft devices on the market.
73 de N1UL
How is a higher Ft device more stable?
Well said
Sent from my iPhone
> On Oct 14, 2018, at 4:14 PM, Gerhard Hoffmann wrote:
>
>
>
>> Am 14.10.2018 um 18:47 schrieb Dana Whitlow:
>> Corby,
>>
>> Now that I learn that the BFT66 is a "wild one", I'd remark that stability
>> is
>> indeed the likely issue. I was puzzled by the
Well some of the 7 GHz and higher Ft transistors have internal matching
networks to prevent such oscillations, but yes it is an important issue.
73 de N1UL
Sent from my iPhone
> On Oct 14, 2018, at 4:14 PM, Richard (Rick) Karlquist
> wrote:
>
>
>
>> On 10/14/2018 11:20 AM, Dr. Ulrich L.
Hi
What you have there is known as a cascade buffer amplifier. The common base
stage combined with the common emitter has some well known issues at high
frequencies ( like UHF / microwave). That’s the tradeoff for having really good
isolation at HF and usually at VHF.
Put a sniffer loop near
Am 14.10.2018 um 18:47 schrieb Dana Whitlow:
Corby,
Now that I learn that the BFT66 is a "wild one", I'd remark that stability
is
indeed the likely issue. I was puzzled by the presence of that capacitor in
the first place, as this circuit is clearly neither tuned nor of especially
high
On 10/14/2018 11:20 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
Actually the BFT is out of production since quite a while there are more stable
and higher Ft devices on the market.
73 de N1UL
How is a higher Ft device more stable? Those attributes
would seem to be mutually exclusive.
The BFT66 if that is the type ( a bit difficult to read ) is a really "wild
one" on VHF. I have used it and unless surrounded by proper decoupling networks
in a well designed circuit it can and will oscillate.
I would have used a spectrum analyzer to check for any unwantedoscillations
well
Corby -
>From the schematic it does not look like anything special but only a 50 ohm
in and out circuit with fairly high isolation due to the common base of the
second BFT66. You may be able to simply use a newer MMIC from one of the
many sources to replace the assembly if you know the gain.
Hi,
I removed this amp from the EFOS2 Maser as it was intermittent.
Of course now I can't get it to fail on the bench!
I have fabricated a new PC board to replace it and have the components on
hand.
Note the 12pfd cap on the collector .
Some notes I have indicate is select at test and that is
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