Some chucklehead removed the antenna selector switch from this R7 I just acquired. Is there any chance anybody might have one?

It’s a beast of a switch with 5 sections, only two of which would be considered “standard” configuration.


Gary

W0DVN

On Apr 23, 2021, at 6:44 PM, Jerry Kessler <N4JL.cw@...> wrote:

Gary,

I believe you are describing the MMK-7 Kit to make the TR-7 more portable for mobile operation. I may have the instructions somewhere. I'll look if you are have further interest.

Jerry, N4JL


At 06:27 PM 4/23/2021, you wrote:

I have a TR7 with a handle on its side and a module on the back holding a power fuse for the 13.8 volts.

This is factory original but I have never seen this version before. The side handle is the same as that seen on the pS7. The rear fuse module is installed where the FA7 would go.

Anyone heard of this version?

Gary

W0DVN

PS: The radio works fine!

On Apr 23, 2021, at 5:21 PM, Gary Follett <xntrick1948@...> wrote:

?I have a TR7 with a handle on its side and a module on the back holding a power fuse for the 13.8 volts.

This is factory original but I have never seen this version before. The side handle is the same as that seen on the pS7. The rear fuse module is installed where the FA7 would go.

Anyone heard of this version?

Gary

W0DVN

PS: The radio works fine!

I have a TR7 with a handle on its side and a module on the back holding a power fuse for the 13.8 volts.

This is factory original but I have never seen this version before. The side handle is the same as that seen on the pS7. The rear fuse module is installed where the FA7 would go.

Anyone heard of this version?

Gary

W0DVN

PS: The radio works fine!

On Apr 23, 2021, at 5:46 PM, Joe Pyles <epyles@...> wrote:

The case with the handle and the power filter were part of the MMK7 mobile mounting kit.

73, Joe Pyles KC9LAD

At 06:27 PM 4/23/2021, you wrote:

I have a TR7 with a handle on its side and a module on the back holding a power fuse for the 13.8 volts.

This is factory original but I have never seen this version before. The side handle is the same as that seen on the pS7. The rear fuse module is installed where the FA7 would go.

Anyone heard of this version?

Gary

W0DVN

PS: The radio works fine!

--
This email has been checked for viruses by AVG.






<MMK-7.pdf>

I have a TR7 with a handle on its side and a module on the back holding a power fuse for the 13.8 volts.

This is factory original but I have never seen this version before. The side handle is the same as that seen on the pS7. The rear fuse module is installed where the FA7 would go.

Anyone heard of this version?

Gary

W0DVN

PS: The radio works fine!

Look at

This may not address your problem, but in any case I am sure you might find it interesting as might others.

Regards

Martin, HS0ZED

On 4/23/21 16:52, Lionel B wrote:

Hi Steve,

It's S/N 22970 and the schematic show a number of the Drake revisions.? Yes, this is a 6EJ7 3rd mixer.?

Peter, the AR forum thread is interesting, and I wonder if I am correct in assuming all 21xxx - 23xxx have the same issue.?

It seems to be very sensitive to any wiring being moved, like the design is right on the edge where proper design would suggest not using wire placement as a "tuneup" aid.?

I like the IF filter leakage article as the blow by around the CW filters has always been annoying, enough so that I talked to Bill Frost long ago (78?) about this issue.? He told me that this was how the design worked and there was no update or mod suggested.?

An abundance of food Peter.? tnx.

>Check out this link first:
>

I would have given more credence to the post if he had not brought in all the drama.? For example, it’s Sherwood’s prerogative to accept or reject a request for repair.? Of what value was it to the posted discussion??

From my perspective, the only added value was this line:

>”Finally when getting to know your R4-C, get the right manual for your tube-lineup…”

Paul, W9AC

Look at

This may not address your problem, but in any case I am sure you might find it interesting as might others.

Regards

Martin, HS0ZED

On 4/23/21 16:52, Lionel B wrote:

Hi Steve,

It's S/N 22970 and the schematic show a number of the Drake revisions.? Yes, this is a 6EJ7 3rd mixer.

Lionel:

Thanks for the info.....this one got me snooping around a bit.

Check out this link first:


I cannot reproduce what you see (rise in S-meter reading with passband tuning at 12 o'clock in SSB modes) on my 25,xxx and 28,xxx R-4C's.? I have one more earlier one yet to try.? It IS reported in that thread in another R-4C in the 23,xxx range, which is closer to yours.

The really interesting part comes later in the lengthy "Sherwood bashing" dissertation by "Noddy", but he refers to an article I had not seen before here:



This article goes into what appears to me as a potential solution to the leakage problem, which you could do in small steps, with measurable results along the way, taking it only as far as one needs to in order to achieve satisfactory performance.? It does get pretty complicated and invasive by the end.? After reading this, I have to wonder if Drake moved some components around to reduce leakage in later production, possibly explaining why I do not see it in my two relatively high serial # radios.

Hope that gives you some food for thought.

73,
Peter
VE7PS

On 2021-04-22 12:56 p.m., Lionel B wrote:

I've seen an article about this topic and unfortunately cannot find the document. The receiver has been "on the shelf" in an air conditioned shack for about 20 years and now I've been going through and aligning per the manual.? When rotating the passband tuning from LSB to USB there is a peak at center that moves the S meter up to about S4 while on either end it falls to S0.? I've had this rx since 1976 and have aligned many times, but this seems new.

The BFO seems to be getting into the 50Khz IF.? Its a mystery.?

I seem to recall reading an alignment doc that has you test for minimum BFO feedthru as shown by the S meter, and a way to correct the problem.?

Am I making any sense at all?

Has anyone encountered this on an R4C??

I've seen an article about this topic and unfortunately cannot find the document. The receiver has been "on the shelf" in an air conditioned shack for about 20 years and now I've been going through and aligning per the manual.? When rotating the passband tuning from LSB to USB there is a peak at center that moves the S meter up to about S4 while on either end it falls to S0.? I've had this rx since 1976 and have aligned many times, but this seems new.

The BFO seems to be getting into the 50Khz IF.? Its a mystery.?

I seem to recall reading an alignment doc that has you test for minimum BFO feedthru as shown by the S meter, and a way to correct the problem.?

Am I making any sense at all?

Has anyone encountered this on an R4C??

Hi Steve,

It's S/N 22970 and the schematic show a number of the Drake revisions.? Yes, this is a 6EJ7 3rd mixer.?

From: "Richard Knoppow" <1oldlens1@...>
To: [email protected]
Sent: Friday, April 23, 2021 9:18:43 AM
Subject: Re: [DRAKE-RADIO] OT: SOLA CV Transformer

?? Sola transformers also have capacitors. If the value of the
capacitor changes it will change the regulation and may make it
run hot. I have had a couple of CVTs, not Solas but other makes,
go bad in Boonton instruments, they use CVTs to directly drive
the rectifiers. I have never been able to find a fix other than
just replacing them. The normally run quite hot but should not
melt the potting compound. I also have a couple of Sola free
standing transformers where the output voltage is wrong and where
I could not correct it with new capacitors. I don't know what
happens to them but suspect it may be a change in the air gap in
the core.

On 4/23/2021 6:26 AM, n4buq wrote:

Looking for some help with an older SOLA CVT. Please reply off-list if
appropriate but others may be interested.

I'm working on an ancient VTVM, a model 800A made by Technology Instruments
Incorporated (later became Acton). There are some pictures of one like
mine here:



The SOLA started overheating after several minutes of powering the meter
and would eventually drop the output voltage dramatically (spec'd at 6VAC
output and dropped to around 2VAC as I remember).

The transformer is(was) housed in a tar-filled metal box and, instead of
digging around very much in that tar at unknown entrails, I decided to
freeze the entire assembly and then some rather caveman-like activities to
force the transformer out of the box. That process caused a few of the
transformer's laminations to "fan" out a bit and, given the odd
frequencies that are generated in this CVT, it buzzes somewhat more than
it did.

I've powered it back up outside of the box and, while it takes a bit longer
to fail, it does eventually drop the output voltage when the capacitor
overheats (I'm planning to replace that cap).

Would it be a bad thing to drill some small holes through the laminations
and secure them with small nuts and bolts (4-40 or smaller)? I can clamp
the laminations and silence it significantly but not sure if small holes
with additional metal through the laminations would affect the operation
of the transformer.

From what I can tell, two rivets extend through the laminations at both
ends of the transformer and lock them to the core. I'm not sure, but I
think it's possible to remove those rivets, remove the laminations,
flatten the laminations that need it, and then reassemble it with small
nuts and bolts. That might be a better alternative but, again, not sure
what effects that might have.

Any advice appreciated.

Thanks,
Barry - N4BUQ

--
Richard Knoppow
1oldlens1@...
WB6KBL

Looking for some help with an older SOLA CVT. Please reply off-list if appropriate but others may be interested.

I'm working on an ancient VTVM, a model 800A made by Technology Instruments Incorporated (later became Acton). There are some pictures of one like mine here:



The SOLA started overheating after several minutes of powering the meter and would eventually drop the output voltage dramatically (spec'd at 6VAC output and dropped to around 2VAC as I remember).

The transformer is(was) housed in a tar-filled metal box and, instead of digging around very much in that tar at unknown entrails, I decided to freeze the entire assembly and then some rather caveman-like activities to force the transformer out of the box. That process caused a few of the transformer's laminations to "fan" out a bit and, given the odd frequencies that are generated in this CVT, it buzzes somewhat more than it did.

I've powered it back up outside of the box and, while it takes a bit longer to fail, it does eventually drop the output voltage when the capacitor overheats (I'm planning to replace that cap).

Would it be a bad thing to drill some small holes through the laminations and secure them with small nuts and bolts (4-40 or smaller)? I can clamp the laminations and silence it significantly but not sure if small holes with additional metal through the laminations would affect the operation of the transformer.

From what I can tell, two rivets extend through the laminations at both ends of the transformer and lock them to the core. I'm not sure, but I think it's possible to remove those rivets, remove the laminations, flatten the laminations that need it, and then reassemble it with small nuts and bolts. That might be a better alternative but, again, not sure what effects that might have.

Any advice appreciated.

Thanks,
Barry - N4BUQ