"Peter Bent" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Thanks Gary,
I am running the Drake Fan (FA-7 #1529) on the TR-7 and the power
supply and they are blowing out... you know they are there, but not at all
bothersome to me. I wonder how long warm up would take if they were not
there.. Probably a lot less.
At the moment I am not going to become fanatical, my present needs
are met. But it is very good to know of options. I will do a little more
research... thanks again.
N2CME
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Garey Barrell
Sent: Saturday, August 25, 2007 4:31 PM
To: [EMAIL PROTECTED]
Subject: Re: [drakelist] Drift on TR7
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Peter -
OK. The fan really helps with stability, keeping the interior of the
transceiver more stable over time. The Drake fan is nearly silent, and
the Rotron "Sprite" SU2C1 is similar and less expensive than the
"collectible" Drake fan! I think Digikey and Mouser still stock them.
Mounted on the provided hole in the rear panel, blowing OUT, it keeps
the chassis at a more stable temperature especially with long-winded,
high power transmit cycles.!! :-)
There are aftermarket "Huff-Puff" stabilizer mods that keep it within a
few Hz, and if price is no object you an always go with one of the
aftermarket external DDS devices or even the Drake RV-75, although the
latter will cost you more than the TR-7 AND the power supply!
Anyway, a properly operating TR-7 with the fan is stable enough for just
about anything you might want to do. Some say it's not stable enough
for PSK-31, although I find a warmed up TR-7 with fan is more than
stable enough, especially if you turn down the transmitter power to
PSK-31 appropriate levels.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Peter Bent wrote:
> "Peter Bent" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
> ----------------------------------------------------------------------
> Hi Gary
>
> I am happy, but very embarrassed to report that I should have been
> talking Hertz not Kilohertz. I just ran a more careful test. After
fifteen
> minutes the Tr7 increased (went from 3999.0 to 3999.2), 200 Hertz. I am
> going to track it for the next half hour and see what the read out is. It
> "seemed" to me that the read out this morning, after warm up, shifted more
> than in the past. Although the radio was in the morning sun..but I will
> check the read out in 30 minutes.
> I am still printing out the information that you sent so I can put
> it in the TR & file. Thanks for your help... with a red face, N2CME
>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On
> Behalf Of Garey Barrell
> Sent: Saturday, August 25, 2007 3:10 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [drakelist] Drift on TR7
>
>
> Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist
gang
> ----------------------------------------------------------------------
> Peter -
>
> The specification is "total drift is less than 100 Hz after warm up" and
> "total frequency change is less than 100 Hz over the 11-16 V-dc input
> supply range."
>
> So no, yours is not typical! :-) Basically the TR-7 is about the same
> stability as the 4 Line separates, and shouldn't move noticeably after a
> 5-10 minute warm up period. Some claim the dial lamp causes instability
> by supplying heat so close to the PTO, but in my experience all it seems
> to do is to speed up the warm up process.
>
> Obviously the +10, +10R and +10T must be stable to begin with. Do NOT
> adjust the +10 pot on the small power supply board unless you are
> prepared to do a complete alignment.
>
> If yours is moving +/- 1 kHz, there is a problem, most likely with the
> PTO. There is a 10V Zener diode inside the PTO can that can cause
> problems, along with the FET oscillator device, although the FET is
> usually more of a "wandering in small jumps" problem.
>
> Another problem I have seen is with the MC14016 (U1) on the Parent
> board, that handles the RIT control, becoming flaky. Again, this usually
> presents as dithering in small jumps rather than "drift".
>
> About all you can do is to measure the PTO with a counter and see if
> that IS the source, and if it is, look at the RIT DC control voltages in
> and out of U1 and see if they are stable or can be correlated with the
> drift. The rest of the oscillators are either crystal controlled or
> phase locked to a crystal and aside from really strange problems are
> either locked and stable or wildly wandering.
>
> Maybe some of the other repair guys on the reflector have some other
> ideas!!?
>
> 73, Garey - K4OAH
> Glen Allen, VA
>
> Drake 2-B, 4-B & C-Line Service Supplement CDs
> <www.k4oah.com>
>
>
>
> Peter Bent wrote:
>
>> Am a happy new owner of as Drake tr 7. The rig checks out so far, on
>> all fronts. There does seem to be some drift in frequency. After it
>> warms ups, about 45 minutes, it pretty much stablilizes, but seems to
>> wander up and down a bit. About 1khz +/-. I certainly can live with
>> this problem. is this typical for the TR7? Any sage advice from
>> anyone. thanks.
>>
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