I'm thinking about going ahead and replacing the vernier drive for the
plate cap on my L-4B.? I got a pointer from Max-Gain for the vernier.?
The new vernier seems a bit tight to me, but I've only tried it with a
1/2" or so diameter knob.? It may be much easier to turn with the larger
2" knob.? Question for the group is does one lubricate the vernier drive
as routine maintenance??? If so, what does one use to lubricate it?

73

Stan
KM4HQE

Jim,

Thanks for the cap info. Will get an orrder in shortly. Want to do some in-circuit testing first. I am beginning to think I might actually be able to do this!??

Best,

RB

This is the list from my Mouser project file. Note: I usually order extras beyond what I need, especially if I am near a price break. I am also attaching my log of measured values of the old caps if you need any convincing on the Capars. Open Office spreadsheet.

Mouser # Mfr. # Manufacturer Customer # Description Order Qty.
594-2222-138-15102 MAL213815102E3 Vishay Aluminum Electrolytic Capacitors - Axial Leaded 1000uF 16V 20% Axial RoHS Compliant 3
594-2222-138-25101 MAL213825101E3 Vishay Aluminum Electrolytic Capacitors - Axial Leaded 100uF 16V 20% Axial RoHS Compliant 2
594-2222-138-35229 MAL213835229E3 Vishay Aluminum Electrolytic Capacitors - Axial Leaded 22uF 16V 20% Axial RoHS Compliant 10
75-TE1155-E3 TE1155-E3 Vishay Aluminum Electrolytic Capacitors - Axial Leaded 16V 10uF AXIAL RoHS Compliant 3



On Thu, 25 Jan 2024 10:59:33 -0800
"Rick K8EZB" <frboswell@...> wrote:

Can you recommend suitable replacements, especially of appropriate physical size?

--

73

-Jim
NU0C

That's basically what I said. All that is needed for a vertical "dipole" is a quarter wavelength of wire and a common mode choke a quarter wavelength back down the shield. The outside of the coax shield will happily radiate, regardless of the insulation. But everyone seems to want to do more work than is necessary. :D

73

-Jim
NU0C

On Thu, 25 Jan 2024 22:13:29 +0000
"rls19" <rls19@...> wrote:

Michael,

You could put a clamp-on choke 1/4-wave down the coax, coil the coax up at that point as a choke, or just slide a 1/4-wave piece of copper tubing over the coax and solder the braid to it.

73,
Bob AD3K
________________________________
From: [email protected] <[email protected]> on behalf of Michael Smith via groups.io <tw8kcabpilot@...>
Sent: Tuesday, January 23, 2024 11:20 PM
To: [email protected] <[email protected]>
Subject: Re: [DRAKE-RADIO] Outer Coaxial Jacket Removal for a Long Length

Thanks to all responding. I found the tool, a new GC brand on Ebay in Pennsylvania, not far away. A better understanding of what I was looking for helped much. As a side note, I’ve decided to use RG-11 for this seamless feed-system/antenna (vertical polarized), after calculating the power handling capability of the Belden 8279 — pret-ty small.
Take care.

73,
Michael, N4KZO

--

73

-Jim
NU0C

开云体育

Which Jim? :D

Well, if he would quit using the Steve font....

73

-James



On Thu, 25 Jan 2024 11:35:29 -0800
"Rick K8EZB" <frboswell@...> wrote:

Peter,

Thanks for the additional info.

On Thu, Jan 25, 2024 at 11:24 AM, VE7PS wrote:

Why do people keep calling me Steve?

Only because Jim did. That's mild compared to what some call me!? ;-)

RB

--

73

-Jim
NU0C

I do have a list. I'll see if I can dig it up for you a bit later.



On Thu, 25 Jan 2024 10:59:33 -0800
"Rick K8EZB" <frboswell@...> wrote:

The caps are a good place to start. Can you recommend suitable replacements, especially of appropriate physical size?

--

73

-Jim
NU0C

开云体育

I forgot to mention the height. ?My understanding is that a 50 foot tower height is a standard height. ?Being this is approximately 15 meters, a full wave length height for the 15 meter band, the lowest frequency band in the range of this log periodic antenna, and above obstacles around me, I expect a 50 foot tower would be a good choice. ?Concerning a rotator, I need recommendations also. ?Please help if possible.

Thank you.

73,
Michael Smith, N4KZO

Peter,

Thanks for the additional info.

Steve,

Yes, good catch! I was so preoccupied with the obvious failed resistor that I overlooked the other failed resistor.

Jim,

you may be seeing power source issues due to failed caps.

My first thougfhts as well. With two failed resistors it makes no sense to simply replace the resistors. I need to find what is causing these to fail. The caps are a good place to start. Can you recommend suitable replacements, especially of appropriate physical size?

Looks like I am going to learn more about the RV75 than I ever wanted to know!

Best,

RB

?

I’m considering putting up the subject antenna. ?KLM is no longer in business to ask them for information. ?Does anyone know the wind load rating and survival wind speed?

Also, this antenna weighs 24 lbs. ?What would be the best non-guyed tower to use?

Thank you.

73,
Michael Smith, N4KZO

Right off the top of my head is you may be seeing power source issues due to failed caps. The Capars are evil incarnate, but it would not be a bad idea to recap all of the electros.

I have too many project right now, so don't even ask. :) Two broken amps to fix, a third for another ham, two FM rigs for yet another fellow, two Alpha amps to clean up and put online, and the list goes on....

73

-Jim
NU0C

On Thu, 25 Jan 2024 09:57:21 -0800
"Rick K8EZB" <frboswell@...> wrote:

Jim,

Thanks for the quick reply and photo. Yes, based on your photo, it does look like 10K (keeping in mind that I am looking at the RV75 for the first time ever!).

I am inclined to tack in a new resistor to see if this restores proper operation. If not, I lack the skills, soldering tools and test equipment to go further. Also, this RV75 has plenty of "CRAPar" capacitors. I am looking for someone who will take on the task of further troubleshooting, appropriate parts replacement and testing. Given the scarcity of the RV75, I am inclined to want to fix it rather than junk it. Any suggestions appreciated.

Best,

RB

--

73

-Jim
NU0C

Good catch. I missed that one. 150 Ohms in the pic I attached. Looks like it is the resistor in series with L205. Better check CR207 for damage too.

73

-Jim
NU0C

On Thu, 25 Jan 2024 09:48:49 -0800
"VE7PS" <ve7ps@...> wrote:

Rick:

You actually seem to have TWO failed resistors there. One is just above
P/J 206 in the pic - the one that's split in half...but if you look to the
right of that P/J, you'll see another burned resistor. I can open my RV-75
and take a look within the hour. Schematic isn't helping much and want to
be sure.

73
Peter
VE7PS

On Mon, Mar 13, 2023 at 10:23?AM Rick Boswell <frboswell@...> wrote:

I began checking out a new-to-me RV75 this AM and am seeing some issues I
dont yet understand. These are:

1. While the RV75 seems to be working in a basic fashion, the frequency
displayed on the TR7 varies by as much a 2 KHz over time, even with an
extneded warmup and without touching the tuning knob.
2. It is nearly impossible to set the frequenciny to the desired 100 Hz
increment; very small movements of the tuning knob produce a few hundred Hz
change in the displayed frequency.
3. The "Fixed Frequency" feature does not display the programmed
frequency. Programming is a bit convoluted but I have verified several
times that the switch settings are as described in the manual.

This is a a late serial number RV75 in very nice overall condition and was
serviced by Ron Baker in 2015; his invoice shows only minimal work needed.
My TR7 works as expected with an RV7 in place of the RV75.

So, wondering how best to proceed. Problems may be pilot error due to lack
of familiarity, but if so, not clear what the pilot is doing wrong. I have
a manual but am reluctant to dive into troubleshooting without a better
understanding as to what might cause these symptoms. Any guidance
appreciated.

Rick
K8EZB

--

73

-Jim
NU0C

Jim,

Thanks for the quick reply and photo. Yes, based on your photo, it does look like 10K (keeping in mind that I am looking at the RV75 for the first time ever!).

I am inclined to tack in a new resistor to see if this restores proper operation. If not, I lack the skills, soldering tools and test equipment to go further. Also, this RV75 has plenty of?"CRAPar" capacitors. I am looking for someone who will take on the task of further troubleshooting, appropriate parts replacement and testing. Given the scarcity of the RV75, I am inclined to want to fix it rather than junk it. Any suggestions appreciated.

Best,

RB