Re: TR-4C Problems with 28.0 and 28.5 bands

#81994

Good idea! I inspected all the tabs on the band switches this evening. I found 3 fingers that didn't look correct and fixed them. Then gave it ALL a good squirt of deoxit. Turned it on, let it warm up about 30 minutes. Still no 28.0 and 28.5 bands.

73, Dave KD5FX

Re: MN2000 bandswitch parts and capacitor info needed

#81993

n 2025-01-16 19:14, Evan via groups.io wrote:
On a number of ham radio products the "2000 watts" actually means
input power to the final amplifier (linear)Back in the day, ALL ham transmitters were specified in terms of "DC Input".
Even the FCC regulations were in terms of that.  So - a Novice was allowed 75W of
DC input to the final stage.

  They changed it to power output when suitable tools became available - and FCC
inspectors got tired of sticking probes into HV final compartments.  Or so I'm told.

             - Jerry, KF6VB

Re: MN2000 bandswitch parts and capacitor info needed

#81992

On a number of ham radio products the "2000 watts" actually means input power to the final amplifier (linear) not necessarily power input to the product.

On Thursday, January 16, 2025 at 10:06:58 PM EST, DB via groups.io <crdonmax1@...> wrote:

Ed,

?

Thanks for sending the link to that Drake group discussion on the MN2000, it is very good, Jim's discussion of the capacitor bank configurationis especially helpful.?

I followed one of the links on tuner theory from that discussion and it illustrated the potential hi voltage and RF currents that may be encountered within the tuner at various impedance mismatches.? Although they were for a different tuner configuration, the voltage varied to as high as 2KV with a 2KW input.?

Since the MN2000 is rated for Full Power up to 2KW, I'm making the conservative assumption that similar conditions could be present in the MN2000 and need to spec the capacitors accordingly.

However, most of the mica caps of this case style (and proper capacitance value) that I have found thus far have had voltage ratings like 600V, but still looking.

?

Still hoping someone snapped a pic of those capacitors or maybe has a Drake part number cross ref to a mfg number.

?

Thanks

Craig KE5CHT

Re: MN2000 bandswitch parts and capacitor info needed

#81991

Thanks Frank,

?

I will get the list of capacitor values and will measure the mounting bracket hole spacing for the caps and email you to see if you might have some of these.

Thanks

Craig KE5CHT

Re: MN2000 bandswitch parts and capacitor info needed

#81990

Ed,

?

Thanks for sending the link to that Drake group discussion on the MN2000, it is very good, Jim's discussion of the capacitor bank configurationis especially helpful.?

I followed one of the links on tuner theory from that discussion and it illustrated the potential hi voltage and RF currents that may be encountered within the tuner at various impedance mismatches.? Although they were for a different tuner configuration, the voltage varied to as high as 2KV with a 2KW input.?

Since the MN2000 is rated for Full Power up to 2KW, I'm making the conservative assumption that similar conditions could be present in the MN2000 and need to spec the capacitors accordingly.

However, most of the mica caps of this case style (and proper capacitance value) that I have found thus far have had voltage ratings like 600V, but still looking.

?

Still hoping someone snapped a pic of those capacitors or maybe has a Drake part number cross ref to a mfg number.

?

Thanks

Craig KE5CHT

Re: MN2000 bandswitch parts and capacitor info needed

#81989
Edited

Here is a MN-2000 manual FROM 1968 with a parts list. ?Won’t help with voltage ratings for the caps. ?But kinda neat.

?

Here is a nice discussion on tuners with some links:

?

/g/DRAKE-RADIO/topic/mn_2000_technical/97996840

?

Click here: ? ? ?

?

ED WA6WGS

Drake_MN-2000_user.pdf

Re: MN2000 bandswitch parts and capacitor info needed

#81988

hey Craig,

? ? ? ? ? ? ? ? ? ?Will keep eye out for "parts" condition MN-2000. Also when I was searching for a Clipperton bandswitch. Found several places that do or might do a custom bandswitch on the internet and ebay.

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Tom W2TF

On Thursday, January 16, 2025 at 07:30:17 PM EST, Frank Barnes via groups.io <fbw4npn@...> wrote:

Craig, I have quite a few large mica caps, removed from various circuits in a discarded 10KW AM transmitter.? If you can find the values needed, I could send photos to see if these are what you might need.? Assuming you haven't found a reasonable source for new ones.

Frank

W4NPN

Show quoted text

On Thu, Jan 16, 2025 at 7:24?PM DB via <CrDonMax1=[email protected]> wrote:

Hi Tom

?

I havent run across anything online yet about capacitor failures in the MN2000 but have read about a few bandswitch issues.?

In this one both the original bandswitch and original capacitors are all gone and replaced with poor substitutions, so not sure what problem the prev owner had or if they just did a poor shotgun approach in trying to fix it.? Everything else inside and out on this one look very nice so I really hope to get it restored.

Hopefully others on the group will give us some good insight into this.

?

Thanks

Craig KE5CHT

--

Frank Barnes

W4NPN

Chapel Hill, NC

Grid Square FM05

Cell 919.260.7955

Re: MN2000 bandswitch parts and capacitor info needed

#81987

Craig, I have quite a few large mica caps, removed from various circuits in a discarded 10KW AM transmitter.? If you can find the values needed, I could send photos to see if these are what you might need.? Assuming you haven't found a reasonable source for new ones.

Frank

W4NPN

Show quoted text

On Thu, Jan 16, 2025 at 7:24?PM DB via <CrDonMax1=[email protected]> wrote:

Hi Tom

?

I havent run across anything online yet about capacitor failures in the MN2000 but have read about a few bandswitch issues.?

In this one both the original bandswitch and original capacitors are all gone and replaced with poor substitutions, so not sure what problem the prev owner had or if they just did a poor shotgun approach in trying to fix it.? Everything else inside and out on this one look very nice so I really hope to get it restored.

Hopefully others on the group will give us some good insight into this.

?

Thanks

Craig KE5CHT

--

Frank Barnes

W4NPN

Chapel Hill, NC

Grid Square FM05

Cell 919.260.7955

Re: MN2000 bandswitch parts and capacitor info needed

#81986

Hi Tom

?

I havent run across anything online yet about capacitor failures in the MN2000 but have read about a few bandswitch issues.?

In this one both the original bandswitch and original capacitors are all gone and replaced with poor substitutions, so not sure what problem the prev owner had or if they just did a poor shotgun approach in trying to fix it.? Everything else inside and out on this one look very nice so I really hope to get it restored.

Hopefully others on the group will give us some good insight into this.

?

Thanks

Craig KE5CHT

Re: MN2000 bandswitch parts and capacitor info needed

#81985

Following this closely as I was wondering if the original caps ever go bad. Havent had time to do any checking on this MN-2000 other than when I threw it in line. In place of a Palstar a few months back it just acted sort of flaky. It also was a clean hamfest find I purchased to go with my ongoing C-Line project. Any insight to my question greatly appreciated.?

? ? ?tnx, Tom W2TF

On Thursday, January 16, 2025 at 05:58:42 PM EST, DB via groups.io <crdonmax1@...> wrote:

Greetings,

I'm still hoping to find someone who may have info/specs on the original MN-2000 fixed bandswitch capacitors (C12-C15).? These are the larger rectangular mica capacitors mounted below the bandswitch. (A previous owner had removed all the mica caps and installed some small disc caps in their place.

I have the capacitance values but I am concerned in finding suitable capacitors that would be rated to handle the full power rating and RF current that they could be subjected to.

If anyone has pics or specs of the originals with Mfg part number etc,, please let me know.

Thanks again

Craig KE5CHT

?

Re: R4C Sherwood audio mod questions

#81984

Hi Bill.? The roughness I'm hearing isn't bad at all, but I will take a look at that supply line next time I have the receiver opened up.? Thanks.

?

73, Floyd

Re: TR-4C Problems with 28.0 and 28.5 bands

#81983

Are you sure they are the RIGHT crystals?

10meters is ripe for CB conversions.? Sometimes that doesn't work but the crystals may remain...

?

Also, you will find most R-4x receivers with a lot of random crystals plugged in the extra crystal bank.

They are not right but they do give some extra coverage for some fun SWL operation. The 100KHz calibrator signals do not come up in the

right place but...

?

73,

Gary

WB6OGD

?

Re: MN2000 bandswitch parts and capacitor info needed

#81982

Greetings,

I'm still hoping to find someone who may have info/specs on the original MN-2000 fixed bandswitch capacitors (C12-C15).? These are the larger rectangular mica capacitors mounted below the bandswitch. (A previous owner had removed all the mica caps and installed some small disc caps in their place.

I have the capacitance values but I am concerned in finding suitable capacitors that would be rated to handle the full power rating and RF current that they could be subjected to.

If anyone has pics or specs of the originals with Mfg part number etc,, please let me know.

Thanks again

Craig KE5CHT

?

Re: Drake Ad from Feb "73"

#81981

Scary, but very true !

Long live qrp, homebrew and reperable "vintage".

Nor sure my CR100 would qualify for the third category,
but I might get brave enough to try one day...

Michael 2E0IHW

Show quoted text

On 2025-01-15 21:36, Clint VE3CMQ wrote:
The newer rigs are great but good luck if they fail.
They really aren’t repairable after a few years

Re: Drake Ad from Feb "73"

#81980

On 2025-01-15 21:36, Clint VE3CMQ wrote:
The newer rigs are great but good luck if they fail.
They really aren’t repairable after a few years*** Yup.  I was on the West Coast swap net a few weekends ago with my Signal/One.  The
net control congratulated me for succeeding in fixing the thing.  I told him it wasn't that
bad.  Mostly discrete components, schematics available.  Some of the parts hard to find, but
none impossible.

  Compare that to a modern rig with a big ASIC in the middle - 200 pins, surface mount, maybe
BGA, no real data.  My FTDX10 has a problem with the CAT control over USB;  I found the responsible chip, and replaced it.  Still no USB CAT.  No possibility of troubleshooting it - to get at that side of the main board, you have to undo approximately umpteen cables around the perimeter of the board.  You can get the board out, but it ain't gonna work with everything disconnected.  I talked to tech support at Yaesu - they don't fix'em either.  They just replace.  That'll be about a grand, please.

                  - Jerry, KF6VB

Re: TR-4C Problems with 28.0 and 28.5 bands

#81979

yes, the Xtals are there. Just not working.

73, Dave KD5FX

Re: T4XB/R4B Transceive problem

#81978

On 2025-01-16 11:25, Steve Wedge, W1ES/4 via groups.io wrote:
I’ve got a Tek 2465, so it doesn’t measure exact frequency.
*** But it's a damn fine scope.  I've got a 2445.  I've had it
for 30 years.  A few years ago, one of the AC input safety capacitors
gave up the ghost, and also the fan got loose.  Replaced the cap,
epoxied the fan back together, and it's all good.

              - Jerry, KF6VB

Re: T4XB/R4B Transceive problem

#81977

开云体育

Mine compares close to my HP counter. Lucky I guess. We’ll see how it sounds on the air Friday. :-)

Show quoted text

On Jan 16, 2025, at 1:25?PM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:

?
I’ve got a Tek 2465, so it doesn’t measure exact frequency.?

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

Sent from for iOS

On Thu, Jan 16, 2025 at 13:41, Tony Sokol via groups.io <tony.sokol@...> wrote:
Thanks for the feedback. Rather than another receiver I used a scope and it does show a dip. My digital scope also has a built in frequency counter display which matches my HP counter exactly.?

Tony

On Jan 16, 2025, at 6:37?AM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:

?
Lately, my go-to for setting C2 has been setting my IC-7610 to 5645 and setting it to CW. I listen to the note on CW and reverse CW. I can also see the carrier on the spectrum display but the correct frequency is there when the beat notes are the same on CW and CW-R. Much better than trying for zero beat in SSB.?

Setting the carrier null is easy using a scope.?

I’ve not found a really good way of setting the filter match than using the method in the manual, so you will be messing with the balance adjustment and C2 no matter what.?

BTW, it’s easier as well to use a scope to watch the amplitude of the transmitted signal, if you otherwise prefer using the by the book method.?

73,

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

Sent from for iOS

On Thu, Jan 16, 2025 at 02:29, Richard Knoppow via groups.io < 1oldlens1@...> wrote:
If the carrier balance adjustment does nothing something is
seriously wrong. Go over the carrier balance adjustment on P,15 of the
handbook. The balance control should show an definite null. It is more
common that a good null can not be achieved than that the modulator can
not be unbalanced but in either case something is wrong. When working
properly the balanced modulator has a very good null, you really need to
set it using a receiver lightly coupled to the output. C-6 will affect
the null but usually in making it impossible to get a null.
Go over the adjustments again and see what you find. I am disturbed
that the original problem may not have been a bad filter but whatever is
causing this to happen.
A story: when I first got my T4XB I could not null the carrier.
After I got Garry's discs I found the wiring in the photographs didn't
look write. I asked Garry and he confirmed that what was in mine was not
correct, although it looked factory. In fact, the circuit is quite
sensitive to stray capacitance. With the wires as they were the
modulator could not be balanced. I moved them and got the correct deep
null. So, look for something out of place. You should be able to get a
substantial amount of carrier by unbalancing the pot. Actually, you need
it for alignment.
On 1/15/2025 10:28 PM, Tony Sokol via groups.io wrote:
> ?Hi Gang,
> I thought I’d update my progress on the T4XB filter issue that I brought up just before Christmas. I found that I had the mate for the blue USB filter I had mounted years ago. Mounting the new filter which is on the bottom was exciting. Now they match pretty well. I was not able to match them per the manual though. You are told to unbalance the balanced modulator by turning the pot fully CCW. This did nothing so I didn’t have a carrier feeding the filters to balance. Rather than detuning the coil possibly opening another can of worms, I simply went to transceive mode and tuned C2 till they “birdied in”. Then I went back and forth between upper and lower sideband listening to myself. Not only did it sound good but the transmitter oscillator ended up on 5.645008. Close enough. The acid test will come when I check in with the Friday evening gang. Hopefully they will not tell me my shorts are way too tight. ?
> Thank you for all the help and suggestions.
>

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

Re: T4XB/R4B Transceive problem

#81976

I’ve got a Tek 2465, so it doesn’t measure exact frequency.?

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

Sent from for iOS

Show quoted text

On Thu, Jan 16, 2025 at 13:41, Tony Sokol via groups.io <tony.sokol@...> wrote:

Thanks for the feedback. Rather than another receiver I used a scope and it does show a dip. My digital scope also has a built in frequency counter display which matches my HP counter exactly.?

Tony

On Jan 16, 2025, at 6:37?AM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:

?
Lately, my go-to for setting C2 has been setting my IC-7610 to 5645 and setting it to CW. I listen to the note on CW and reverse CW. I can also see the carrier on the spectrum display but the correct frequency is there when the beat notes are the same on CW and CW-R. Much better than trying for zero beat in SSB.?

Setting the carrier null is easy using a scope.?

I’ve not found a really good way of setting the filter match than using the method in the manual, so you will be messing with the balance adjustment and C2 no matter what.?

BTW, it’s easier as well to use a scope to watch the amplitude of the transmitted signal, if you otherwise prefer using the by the book method.?

73,

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

Sent from for iOS

On Thu, Jan 16, 2025 at 02:29, Richard Knoppow via groups.io < 1oldlens1@...> wrote:
If the carrier balance adjustment does nothing something is
seriously wrong. Go over the carrier balance adjustment on P,15 of the
handbook. The balance control should show an definite null. It is more
common that a good null can not be achieved than that the modulator can
not be unbalanced but in either case something is wrong. When working
properly the balanced modulator has a very good null, you really need to
set it using a receiver lightly coupled to the output. C-6 will affect
the null but usually in making it impossible to get a null.
Go over the adjustments again and see what you find. I am disturbed
that the original problem may not have been a bad filter but whatever is
causing this to happen.
A story: when I first got my T4XB I could not null the carrier.
After I got Garry's discs I found the wiring in the photographs didn't
look write. I asked Garry and he confirmed that what was in mine was not
correct, although it looked factory. In fact, the circuit is quite
sensitive to stray capacitance. With the wires as they were the
modulator could not be balanced. I moved them and got the correct deep
null. So, look for something out of place. You should be able to get a
substantial amount of carrier by unbalancing the pot. Actually, you need
it for alignment.
On 1/15/2025 10:28 PM, Tony Sokol via groups.io wrote:
> ?Hi Gang,
> I thought I’d update my progress on the T4XB filter issue that I brought up just before Christmas. I found that I had the mate for the blue USB filter I had mounted years ago. Mounting the new filter which is on the bottom was exciting. Now they match pretty well. I was not able to match them per the manual though. You are told to unbalance the balanced modulator by turning the pot fully CCW. This did nothing so I didn’t have a carrier feeding the filters to balance. Rather than detuning the coil possibly opening another can of worms, I simply went to transceive mode and tuned C2 till they “birdied in”. Then I went back and forth between upper and lower sideband listening to myself. Not only did it sound good but the transmitter oscillator ended up on 5.645008. Close enough. The acid test will come when I check in with the Friday evening gang. Hopefully they will not tell me my shorts are way too tight. ?
> Thank you for all the help and suggestions.
>

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

TR7 - Early version 2nd Mixer Schematic and Pictorial Information (description of parts on the board)

#81975

Greetings all,

?

I am in the need of the schematic and pictorial information for the early series 2nd Mixer Boards. I have only found late version ones. I went through most of the threads regarding the 2nd mixer but I could not find what I need.
As I am trying to convert an early version board into a late version one, I do not want to ruin it doing something silly.

I have quite a bit of information to do the conversion, obtained in the different threads I went through.
My other concern is T701. On the board I have there is a transformer and I am supposed to replace it with a tapped coil. As I have no info on the tapped coil, my plan is to leave the transformer untouched and try the board.
May I ask you for comments, which will be very appreciated.

?

73 de Raoul CE3RY