Help with Drake TR7?
ukii
Hello Gang. I need a little help with my "new" Drake TR7.
First,the filter board,well it has 2 spots filled up. One is supposed to be
the AM filter,the other is the 1.8 SSB filter. The spot that is marked
"B" has no filter in it,but has a resistor stretched across where the
filter should be. The "C" slot was empty. If I set the filter switch to
either A or B,I do hear the audio changing,so I am wondering if
that resistor deal in "slot B" IS the filter? If I click both buttons in,
there is no audio. I have the 500hz cw filter which I was going to install
untill I jazzed it up!
There is a 10k resistor very close to the filter opening and either I
smashed that resistor lead,or it was broke. Anyway,got to replace that,
Radio Shack??? Wattage rating?
One other area I need help...
The rig has the AUX-7 board,but I cant seem to HEAR any of the Broadcast
AM stations down in the AM broadcast band. It seems as if there is full
attenuation in that area... Is there a seperate antenna I need to hook up
somewhere? (thought I read that somewhere)
Any help would be great!
Best 73 de john
N9UKX
(still looking for the remote VFO and an old BUG or KEY)
David Stadt
John:
If you have a FAX number I will copy the TR7 filter installation manual
on Tuesday and FAX it to you. I can FAX a copy of the AUX7 installation
and operation manual also. The filters are rather large metal
rectangular
cans and are definately not resistor sized.
Standard filter selection is as follows:
SWA SWB Filter
Out Out 2.3KHZ Manual says standard and do not move to another position
In Out A
Out In B
In In C
To receive below 1.5 MHZ you need to attach an antenna to pin 7 of
connector K. From the back, K is the second connector from the right.
Mine
is labeled "accessories." Pin seven is on the bottom row, third from
the
right. The mauual says to disconnect this antenna when transmitting and
that having this antenna connected will degrade reception above 1.5 MHZ.
I've got a factory TR7A with PS7, MS7 and RV7. It's about the only
solid state box I have any desire to own. :-)
Dave S.
N9LWO
'AB7HI' Stephen Lee
If you select a filter where none exists then you will not
have any audio upon that selection. Someone tacked on a
resistor in your B filter position but that is not a filter.
This is allowing all of the first IF stage signal to reach
the second IF module. You won't have much selectivity at B.
The AUX-7 option provides for VLF (very low frequency) reception.
This requires a separate VLF antenna. Connect it to pin 7 of the
accessories connector, the largest jones connector on the back of
the rig. It is on the bottom row, 2nd vertical pin over from the
edge. The plug, P/N: P-312-CCT, is pin-numbered inside the hood.
I just bought one new for $3.00. The Drake owner's manual doesn't
show the location of the pins and I didn't find a reference for
Jones plugs in my ARRL Handbook.
The TR-7 cannot transmit VLF and Drake warns to remove the VLF
connection before making any transmission. Also, the VLF antenna
input bypasses some built-in antenna filters. Leaving the VLF
antenna connected will result in degraded receiver performance
on your other bands.
There should be no 10Kohm resistor on the IF selectivity board.
All resistors on this board are 1/4 watt 5% carbon film. Values
will be either 1.0K, 3.3K, or 3.9Kohms. The optional filter
circuits are all identical so perhaps you could "borrow" a part
from the unused filter location. The standard filter location is
pretty close to identical...only has a few extra diodes and maybe
one extra resistor. BTW, the standard filter for the TR-7 is the
2.3Kc SSB filter.
Enjoy,
Stephen Lee, AB7HI, Tacoma,WA
sl...@u.washington.edu
Ed Parish
In article <Pine.A41.3.95b.97011...@homer26.u.washington.edu> 'AB7HI' Stephen Lee <sl...@u.washington.edu> writes:
>If you select a filter where none exists then you will not
>have any audio upon that selection. Someone tacked on a
>resistor in your B filter position but that is not a filter.
>This is allowing all of the first IF stage signal to reach
>the second IF module. You won't have much selectivity at B.
>
See below about the resistor...
>The AUX-7 option provides for VLF (very low frequency) reception.
The AUX board is not necessary for VLF reception. The AUX board allows you
to transmit in 500KHz segments of the band that were not available in the
original 6 amateur bands on the radio. It also allows you to select any of
the 500KHz segment through a know selection, rather than the up/down
buttons.
>edge. The plug, P/N: P-312-CCT, is pin-numbered inside the hood.
>I just bought one new for $3.00. The Drake owner's manual doesn't
You can find these plugs at some flea markets too.
>
>There should be no 10Kohm resistor on the IF selectivity board.
>All resistors on this board are 1/4 watt 5% carbon film. Values
>will be either 1.0K, 3.3K, or 3.9Kohms. The optional filter
>circuits are all identical so perhaps you could "borrow" a part
>from the unused filter location. The standard filter location is
>pretty close to identical...only has a few extra diodes and maybe
>one extra resistor. BTW, the standard filter for the TR-7 is the
>2.3Kc SSB filter.
Although there are none of these resistors on the board, a common trick for
those who wanted AM bandwidth without buying a filter was to jumper the
filter with a resistor.
In installing the filters, I at first found it difficult to remember which on was where. I have standardized the filter locations in my TR7s as follows:
A - Am
B - ssB
C - Cw
This works well when you want to progressively narrow your bandwidth, as
the filters are "gray coded".
Ed K1EP
(an original TR7 owner of 18 years)
--
_..._._ _..._._ _..._._ _..._._ _..._._ _..._._ _..._._ _..._._ _..._._
Ed Parish
epa...@netcom.com
'AB7HI' Stephen Lee
On Thu, 23 Jan 1997, Ed Parish wrote:
> The AUX board is not necessary for VLF reception.
Here's what R.L.Drake advertised on the TR-7, copyright 1978:
"The TR-7/DR-7 provides reception from 1.5 thru 30 MHz continuously,
and zero thru 30MHz continuously with the optional AUX-7 Range Program
Board." My TR-7 is in accordance with the original Drake specification.
If I remove the AUX-7 board the VLF receive capability goes away with it.
> Although there are none of these resistors on the board, a common trick for
> those who wanted AM bandwidth without buying a filter was to jumper the
> filter with a resistor.
Sorry, I will never hack this fine instrument with common tricks. The
price for a filter in 1978 was $49 each and that's about the going price
for a used TR-7 filter today.
>In installing the filters, I at first found it difficult to remember
>which on was where. I have standardized the filter locations in my TR7s
>as follows:
> A - Am
> B - ssB
> C - Cw
> This works well when you want to progressively narrow your bandwidth, as
> the filters are "gray coded".
The Gray code is a binary data coding scheme where the difference between
two adjacent code words is one bit location. The decimal values
0,1,2,3,4,5 in Gray code would be 000,001,011,010,110,111. Where this is
most often applied is in support of control systems using stepping motors.
Gray code has also been applied in Digital-to-Analog converters. On my
TR-7 the filter selection switches work thusly: A: 300Hz CW, B: 6KHz AM,
C: 500Hz CW, and None Selected: 2.3KHz SSB. I have 4 genuine filters.
> Ed K1EP
> (an original TR7 owner of 18 years)
> Ed Parish
> epa...@netcom.com
>
Nice to meet you young man. I am the proud owner of an original Drake TR-7
and I'm 47 years old ;)
Stephen Lee, AB7HI, Tacoma, WA
sl...@u.washington.edu
Ed Parish
In article <Pine.A41.3.95b.97012...@homer24.u.washington.edu> 'AB7HI' Stephen Lee <sl...@u.washington.edu> writes:
>On Thu, 23 Jan 1997, Ed Parish wrote:
>
>> The AUX board is not necessary for VLF reception.
>
>Here's what R.L.Drake advertised on the TR-7, copyright 1978:
>"The TR-7/DR-7 provides reception from 1.5 thru 30 MHz continuously,
>and zero thru 30MHz continuously with the optional AUX-7 Range Program
>Board." My TR-7 is in accordance with the original Drake specification.
>If I remove the AUX-7 board the VLF receive capability goes away with it.
I believe that I was mistaken on this technicality. I believe that the
UP/DOWN buttons will not allow you to go below 1.5M and that you must have
the AUX board select those three 500K segments in order to receive there.
>
>> Although there are none of these resistors on the board, a common trick for
>> those who wanted AM bandwidth without buying a filter was to jumper the
>> filter with a resistor.
>
>Sorry, I will never hack this fine instrument with common tricks. The
>price for a filter in 1978 was $49 each and that's about the going price
>for a used TR-7 filter today.
Fine, all I said was that it has been suggested by some that a resistor in
place of a wide AM filter could be used, relying upon the selectivity of
the IF.
>
>>In installing the filters, I at first found it difficult to remember
>>which on was where. I have standardized the filter locations in my TR7s
>>as follows:
>> A - Am
>> B - ssB
>> C - Cw
>> This works well when you want to progressively narrow your bandwidth, as
>> the filters are "gray coded".
>
>The Gray code is a binary data coding scheme where the difference between
>two adjacent code words is one bit location. The decimal values
>0,1,2,3,4,5 in Gray code would be 000,001,011,010,110,111. Where this is
>most often applied is in support of control systems using stepping motors.
>Gray code has also been applied in Digital-to-Analog converters. On my
>TR-7 the filter selection switches work thusly: A: 300Hz CW, B: 6KHz AM,
>C: 500Hz CW, and None Selected: 2.3KHz SSB. I have 4 genuine filters.
>
I have never personally used stepper motor control systems, however, I have
used Gray coding in many applications. It refers to the fact that the
change from one state to another requires a change in one and only one
binary digit. As it applies to two binary switches selecting four filters
is an exercise left up to the student.
>> Ed K1EP
>> (an original TR7 owner of 18 years)
>> Ed Parish
>> epa...@netcom.com
>>
>Nice to meet you young man. I am the proud owner of an original Drake TR-7
>and I'm 47 years old ;)
And I purchased my *first* TR7 brand new in 1979 and it is still in
operation in my shack today.
Michael St. Angelo
Dear OM,
On the TR7 IF selectivity board the first position on (left
side of the board) is the stock 2.3kHz filter. This is selected
when the both BW switches are not depressed.
The next filter position, A ACCESSORY, is selected by depressing
only the A BW switch. The B switch is not depressed.
The third position B ACCESSORY is selected by depressing only the
B BW switch. The resistor enables you to have a wideband 8-12 khz
filter by using the first IF filter (48.05 MHz filter on the
UP-Converter Board) as the only filtering element.
The fourth position, C ACCESSORY is selected by depressing
both the A and B switch. Note that this is labeled C on the
front panel. Since your rig does not have a filter in this
position you will not hear any signal. Place your CW filter
in this position.
All resistors on the filter board are standard 1/4 watt, 5% carbon
composition resistors.
The VLF antenna input is on pin 7 of the ACCESSORIES connector.
This rig is a good performer on the VLF bands.
Good Luck with the TR7
Mike N2MS
email:msta...@worldnet.att.net