I have no skin in this. ?Someone is selling faceplates for R-4A and R-4B receivers on eBay.?
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
|
Re: L7 input coil ajustment.
I should clarify the last post, now that I¡¯m on my second cup of coffee. ?If the input?SWR is below 2:1 across the band, I wouldn¡¯t bother messing with it.
My L7 has no trouble being driven to full output with my TR7 and that¡¯s ¡°good enough¡± for me. ?My IC-7610 agrees.?
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Tue, Jan 16, 2024 at 7:56 AM, Steve Wedge, W1ES/4 via groups.io < w1es@...> wrote: That¡¯s great news, Howard!
On the 6 ¡°legacy¡± bands, the SWR should be roughly 2:1 or less. ?Honestly, there are only two ways it can change: an bad part or someone being in there before, trying to adjust.and doing it badly (or setting 10m to 11m).
I¡¯d leave well-enough alone.
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Mon, Jan 15, 2024 at 7:39 PM, Howard VE7IGA <howard_kerster@...> wrote: Thanks guys for all the input on input coil adjustment. Ran the amp today on 40m and had a swr of 1.2:1 between amp and L7 at about 1500watts PEP output to flat swr into my dipole.?
Going to check other bands later this week and see how they react. Not sure if I should get into it with that low a swr between Rig and amp.
I may try the idea of the antenna analyser if I can buy or borrow one at a later date,( looking at putting up a 40m loop in back yard and antenna analyser would come in handy for that also). The idea of leaving HV connected isn't for me....already had 1000volt shock and didn't like it a bit and now with 5 stints in? my heart ? don't want to melt them...hi hi. Thanks again for input on input. Love you learn. Howard VE7IGA ps if any of you guys are in the area of Chiiliwack BC some day feel free to drop in see the station and let me pick your brains.
|
Re: L7 input coil ajustment.
That¡¯s great news, Howard!
On the 6 ¡°legacy¡± bands, the SWR should be roughly 2:1 or less. ?Honestly, there are only two ways it can change: an bad part or someone being in there before, trying to adjust.and doing it badly (or setting 10m to 11m).
I¡¯d leave well-enough alone.
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Mon, Jan 15, 2024 at 7:39 PM, Howard VE7IGA < howard_kerster@...> wrote: Thanks guys for all the input on input coil adjustment. Ran the amp today on 40m and had a swr of 1.2:1 between amp and L7 at about 1500watts PEP output to flat swr into my dipole.?
Going to check other bands later this week and see how they react. Not sure if I should get into it with that low a swr between Rig and amp.
I may try the idea of the antenna analyser if I can buy or borrow one at a later date,( looking at putting up a 40m loop in back yard and antenna analyser would come in handy for that also). The idea of leaving HV connected isn't for me....already had 1000volt shock and didn't like it a bit and now with 5 stints in? my heart ? don't want to melt them...hi hi. Thanks again for input on input. Love you learn. Howard VE7IGA ps if any of you guys are in the area of Chiiliwack BC some day feel free to drop in see the station and let me pick your brains.
|
Re: L7 input coil ajustment
To add further to the mix, here is an archived thread from eHam forums on improving the 10 Meter input circuit: /g/DRAKE-RADIO/files/Drake%20L7%2010%20Meter%20High%20Input%20SWR%20complete.pdfOne method I have heard of to isolate the HV feed while working on the amp live is to secure the end of the cable inside a glass jar. 73 -Jim NU0C On Mon, 15 Jan 2024 19:45:19 -0800 "Howard VE7IGA" <howard_kerster@...> wrote: Yup I'm familiar with the two safety switches on my L7's.? And my L7's would both be imports.as they have stock 10m band positions.?On another note did I see that RV75' s are fetching $1000.00US dollars??!!! That's insane. I'll have to put my 2 in a safety deposit box.? ?hihi.Thanks again for everybody's help.? Howard VE7IGA?Sent from my Galaxy
-------- Original message --------From: "Evan via groups.io" <k9sqg@...> Date: 2024-01-15 7:19 p.m. (GMT-08:00) To: [email protected] Subject: Re: [DRAKE-RADIO] L7 input coil ajustment
Fellow Drake Enthusiasts,Two comments.First, unlike the L4B, the L7 has two (2) safety related devices. ?The first is the above chassis high voltage shorting mechanism, the other is a microswitch along the edge, on the underside.Second, there are at least three (3) different designs for enabling the bandswitch to go to the 10M position. ?The first is that little bar that can be removed from the underside of the RF deck; this was a joy for CBers. ?The other two methods are more involved, one of which has a miniature bolt and a round knurled nut; take precautions to prevent parts from falling into the RF deck topside.As a side note, tuning on 10 and 15 meters is extremely broad. ?And on some bands, the length of the coax between the amp and the driving rig can alter the tuning coil adjustments.Just my experiences, I'm not an expert.73,Evan, K9SQG
On Monday, January 15, 2024 at 03:53:58 PM EST, VE7PS <ve7ps@...> wrote:
Howard:I'll add two comments to David's instructions for adjusting the input tuning on the L-71)? Check out the L-4B instructions.? They got that correct and it's the same procedure.2)? While I would not personally recommend adjusting the input tuning with high voltage applied...for safety reasons...but?IF you choose to do so, keep in mind you would also have to defeat the HV interlock to do this with the lid off....which IS necessary to reach the coils.I recently did some work on an L-4B for a ham in Surrey, BC.? I did the input tuning on his amp after undoing some "magic nichrorme" mods and adding in some more modern ones (Electronic Specialties).? Note the input tuning is very broad, though perhaps due to aging of the caps, I did notice a slight improvement on some bands.? As such, I am not in any hurry to adjust the input tuning on my own amps, unless perhaps the tubes get changed at some point.Be careful!73PeterVE7PSOn Sat, Jan 13, 2024 at 11:07?AM Howard VE7IGA <howard_kerster@...> wrote:Hey guys, I'm going to be doing a input coil adjustment on my L7 amp. Eimac tubes are getting very soft and I'm replacing them with RF Parts matched pair.I've done this before and i'm very aware of safety procedures. It's been awhile.I just want to clarify a few things before I start. Procedure (F) I take it that the plate control should also be in the centre of the band I am adjusting , this is not mentioned in procedure. Also when increasing exciter output to achieve a .400 amp. reading on the grid meter, procedure (I) is this correct because my other L7 manual said plate meter.Lastly when tuning the plate control for dip in plate current, procedure (J) is it a greatest dip possible or just a slight dip in plate current??Thanks for any input you can provide. Howard VE7IGA
-- 73 -Jim NU0C
|
Re: L7 input coil ajustment
Yup I'm familiar with the two safety switches on my L7's.? And my L7's would both be imports.as they have stock 10m band positions.? On another note did I see that RV75' s are fetching $1000.00US dollars??!!! That's insane. I'll have to put my 2 in a safety deposit box.? ?hihi. Thanks again for everybody's help.? Howard VE7IGA?
toggle quoted message
Show quoted text
-------- Original message -------- From: "Evan via groups.io" <k9sqg@...> Date: 2024-01-15 7:19 p.m. (GMT-08:00) Subject: Re: [DRAKE-RADIO] L7 input coil ajustment
Fellow Drake Enthusiasts,
Two comments.
First, unlike the L4B, the L7 has two (2) safety related devices. ?The first is the above chassis high voltage shorting mechanism, the other is a microswitch along the edge, on the underside.
Second, there are at least three (3) different designs for enabling the bandswitch to go to the 10M position. ?The first is that little bar that can be removed from the underside of the RF deck; this was a joy for CBers. ?The other two methods are more involved, one of which has a miniature bolt and a round knurled nut; take precautions to prevent parts from falling into the RF deck topside.
As a side note, tuning on 10 and 15 meters is extremely broad. ?And on some bands, the length of the coax between the amp and the driving rig can alter the tuning coil adjustments.
Just my experiences, I'm not an expert.
73,
Evan, K9SQG
On Monday, January 15, 2024 at 03:53:58 PM EST, VE7PS <ve7ps@...> wrote:
Howard:
I'll add two comments to David's instructions for adjusting the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that correct and it's the same procedure.
2)? While I would not personally recommend adjusting the input tuning with high voltage applied...for safety reasons...but?IF you choose to do so, keep in mind you would also have to defeat the HV interlock to do this with the lid off....which IS necessary to reach the coils.
I recently did some work on an L-4B for a ham in Surrey, BC.? I did the input tuning on his amp after undoing some "magic nichrorme" mods and adding in some more modern ones (Electronic Specialties).? Note the input tuning is very broad, though perhaps due to aging of the caps, I did notice a slight improvement on some bands.? As such, I am not in any hurry to adjust the input tuning on my own amps, unless perhaps the tubes get changed at some point.
Hey guys, I'm going to be doing a input coil adjustment on my L7 amp. Eimac tubes are getting very soft and I'm replacing them with RF Parts matched pair.
I've done this before and i'm very aware of safety procedures. It's been awhile.
I just want to clarify a few things before I start. Procedure (F) I take it that the plate control should also be in the centre of the band I am adjusting , this is not mentioned in procedure. Also when increasing exciter output to achieve a .400 amp. reading on the grid meter, procedure (I) is this correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate current, procedure (J) is it a greatest dip possible or just a slight dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
|
Re: L7 input coil ajustment
Fellow Drake Enthusiasts,
Two comments.
First, unlike the L4B, the L7 has two (2) safety related devices. ?The first is the above chassis high voltage shorting mechanism, the other is a microswitch along the edge, on the underside.
Second, there are at least three (3) different designs for enabling the bandswitch to go to the 10M position. ?The first is that little bar that can be removed from the underside of the RF deck; this was a joy for CBers. ?The other two methods are more involved, one of which has a miniature bolt and a round knurled nut; take precautions to prevent parts from falling into the RF deck topside.
As a side note, tuning on 10 and 15 meters is extremely broad. ?And on some bands, the length of the coax between the amp and the driving rig can alter the tuning coil adjustments.
Just my experiences, I'm not an expert.
73,
Evan, K9SQG
On Monday, January 15, 2024 at 03:53:58 PM EST, VE7PS <ve7ps@...> wrote:
Howard:
I'll add two comments to David's instructions for adjusting the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that correct and it's the same procedure.
2)? While I would not personally recommend adjusting the input tuning with high voltage applied...for safety reasons...but?IF you choose to do so, keep in mind you would also have to defeat the HV interlock to do this with the lid off....which IS necessary to reach the coils.
I recently did some work on an L-4B for a ham in Surrey, BC.? I did the input tuning on his amp after undoing some "magic nichrorme" mods and adding in some more modern ones (Electronic Specialties).? Note the input tuning is very broad, though perhaps due to aging of the caps, I did notice a slight improvement on some bands.? As such, I am not in any hurry to adjust the input tuning on my own amps, unless perhaps the tubes get changed at some point.
Hey guys, I'm going to be doing a input coil adjustment on my L7 amp. Eimac tubes are getting very soft and I'm replacing them with RF Parts matched pair.
I've done this before and i'm very aware of safety procedures. It's been awhile.
I just want to clarify a few things before I start. Procedure (F) I take it that the plate control should also be in the centre of the band I am adjusting , this is not mentioned in procedure. Also when increasing exciter output to achieve a .400 amp. reading on the grid meter, procedure (I) is this correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate current, procedure (J) is it a greatest dip possible or just a slight dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
|
Re: L7 input coil ajustment
I use and have used the MFJ series.? It is an old one, but I have found them quite handy. David Assaf III W5XU, VP8RXU ?
? Excellent thread thanks for all the good information. I am just completing refurbishing an L4 B and will be tuning it up. Your insight is much appreciated. Do you have a recommendation on an antenna analyzer? Thanks for all the good information. It is much appreciated. John S AA0ES? On Jan 15, 2024, at 3:47?PM, Paul Kraemer <elespe@...> wrote:
?
Accepted---thanks
K0UYA
On 1/15/2024 3:20 PM, VE7PS wrote:
Ooops...sorry Paul....I wrote that very poorly and
didn't pick it up in the proofread!
Actually, while nichrome parasitics?WERE removed from that
amp (and I made my own copies of the originals to replace
them), there were other mods in the input circuit that were
also removed.? Paul's ESAC-Harbach all-in board was installed
in the amp and it is THAT I was referring to.? I have?been a
strong proponent of Paul's products for many years.? My
statement was never meant to cause any misunderstanding?or
harm.
Again....sorry Paul!
73
Peter
VE7PS
On Mon, Jan 15, 2024 at
1:07?PM Paul Kraemer < elespe@...>
wrote:
For the record? I have NO parasitic suppressors new or
old for ANY amplifier.
For the record.
Apology forthcoming?
Paul K0UYA
On 1/15/2024 2:53 PM, VE7PS wrote:
Howard:
I'll add two comments to David's instructions for
adjusting the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that
correct and it's the same procedure.
2)? While I would not personally
recommend adjusting the input tuning with high voltage
applied...for safety reasons...but?IF you
choose to do so, keep in mind you would also have to defeat
the HV interlock to do this with the lid
off....which IS necessary to reach the coils.
I recently did some work on an L-4B for a ham in
Surrey, BC.? I did the input tuning on his amp after
undoing some "magic nichrorme" mods and adding in some
more modern ones (Electronic Specialties).? Note the
input tuning is very broad, though perhaps due to
aging of the caps, I did notice a slight improvement
on some bands.? As such, I am not in any hurry to
adjust the input tuning on my own amps, unless perhaps
the tubes get changed at some point.
Be careful!
73
Peter
VE7PS
Hey guys, I'm going to
be doing a input coil adjustment on my L7 amp. Eimac
tubes are getting very soft and I'm replacing them
with RF Parts matched pair.
I've done this before and i'm very aware of safety
procedures. It's been awhile.
I just want to clarify a few things before I start.
Procedure (F) I take it that the plate control should
also be in the centre of the band I am adjusting ,
this is not mentioned in procedure. Also when
increasing exciter output to achieve a .400 amp.
reading on the grid meter, procedure (I) is this
correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate
current, procedure (J) is it a greatest dip possible
or just a slight dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
|
Thanks guys for all the input on input coil adjustment. Ran the amp today on 40m and had a swr of 1.2:1 between amp and L7 at about 1500watts PEP output to flat swr into my dipole.?
Going to check other bands later this week and see how they react. Not sure if I should get into it with that low a swr between Rig and amp.
I may try the idea of the antenna analyser if I can buy or borrow one at a later date,( looking at putting up a 40m loop in back yard and antenna analyser would come in handy for that also). The idea of leaving HV connected isn't for me....already had 1000volt shock and didn't like it a bit and now with 5 stints in? my heart ? don't want to melt them...hi hi. Thanks again for input on input. Love you learn. Howard VE7IGA ps if any of you guys are in the area of Chiiliwack BC some day feel free to drop in see the station and let me pick your brains.
|
Re: L7 input coil ajustment
? Excellent thread thanks for all the good information. I am just completing refurbishing an L4 B and will be tuning it up. Your insight is much appreciated. Do you have a recommendation on an antenna analyzer? Thanks for all the good information. It is much appreciated. John S AA0ES?
toggle quoted message
Show quoted text
On Jan 15, 2024, at 3:47?PM, Paul Kraemer <elespe@...> wrote:
?
Accepted---thanks
K0UYA
On 1/15/2024 3:20 PM, VE7PS wrote:
Ooops...sorry Paul....I wrote that very poorly and
didn't pick it up in the proofread!
Actually, while nichrome parasitics?WERE removed from that
amp (and I made my own copies of the originals to replace
them), there were other mods in the input circuit that were
also removed.? Paul's ESAC-Harbach all-in board was installed
in the amp and it is THAT I was referring to.? I have?been a
strong proponent of Paul's products for many years.? My
statement was never meant to cause any misunderstanding?or
harm.
Again....sorry Paul!
73
Peter
VE7PS
On Mon, Jan 15, 2024 at
1:07?PM Paul Kraemer < elespe@...>
wrote:
For the record? I have NO parasitic suppressors new or
old for ANY amplifier.
For the record.
Apology forthcoming?
Paul K0UYA
On 1/15/2024 2:53 PM, VE7PS wrote:
Howard:
I'll add two comments to David's instructions for
adjusting the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that
correct and it's the same procedure.
2)? While I would not personally
recommend adjusting the input tuning with high voltage
applied...for safety reasons...but?IF you
choose to do so, keep in mind you would also have to defeat
the HV interlock to do this with the lid
off....which IS necessary to reach the coils.
I recently did some work on an L-4B for a ham in
Surrey, BC.? I did the input tuning on his amp after
undoing some "magic nichrorme" mods and adding in some
more modern ones (Electronic Specialties).? Note the
input tuning is very broad, though perhaps due to
aging of the caps, I did notice a slight improvement
on some bands.? As such, I am not in any hurry to
adjust the input tuning on my own amps, unless perhaps
the tubes get changed at some point.
Be careful!
73
Peter
VE7PS
Hey guys, I'm going to
be doing a input coil adjustment on my L7 amp. Eimac
tubes are getting very soft and I'm replacing them
with RF Parts matched pair.
I've done this before and i'm very aware of safety
procedures. It's been awhile.
I just want to clarify a few things before I start.
Procedure (F) I take it that the plate control should
also be in the centre of the band I am adjusting ,
this is not mentioned in procedure. Also when
increasing exciter output to achieve a .400 amp.
reading on the grid meter, procedure (I) is this
correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate
current, procedure (J) is it a greatest dip possible
or just a slight dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
|
Re: L7 input coil ajustment
Accepted---thanks
K0UYA
On 1/15/2024 3:20 PM, VE7PS wrote:
toggle quoted message
Show quoted text
Ooops...sorry Paul....I wrote that very poorly and
didn't pick it up in the proofread!
Actually, while nichrome parasitics?WERE removed from that
amp (and I made my own copies of the originals to replace
them), there were other mods in the input circuit that were
also removed.? Paul's ESAC-Harbach all-in board was installed
in the amp and it is THAT I was referring to.? I have?been a
strong proponent of Paul's products for many years.? My
statement was never meant to cause any misunderstanding?or
harm.
Again....sorry Paul!
73
Peter
VE7PS
On Mon, Jan 15, 2024 at
1:07?PM Paul Kraemer < elespe@...>
wrote:
For the record? I have NO parasitic suppressors new or
old for ANY amplifier.
For the record.
Apology forthcoming?
Paul K0UYA
On 1/15/2024 2:53 PM, VE7PS wrote:
Howard:
I'll add two comments to David's instructions for
adjusting the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that
correct and it's the same procedure.
2)? While I would not personally
recommend adjusting the input tuning with high voltage
applied...for safety reasons...but?IF you
choose to do so, keep in mind you would also have to defeat
the HV interlock to do this with the lid
off....which IS necessary to reach the coils.
I recently did some work on an L-4B for a ham in
Surrey, BC.? I did the input tuning on his amp after
undoing some "magic nichrorme" mods and adding in some
more modern ones (Electronic Specialties).? Note the
input tuning is very broad, though perhaps due to
aging of the caps, I did notice a slight improvement
on some bands.? As such, I am not in any hurry to
adjust the input tuning on my own amps, unless perhaps
the tubes get changed at some point.
Be careful!
73
Peter
VE7PS
Hey guys, I'm going to
be doing a input coil adjustment on my L7 amp. Eimac
tubes are getting very soft and I'm replacing them
with RF Parts matched pair.
I've done this before and i'm very aware of safety
procedures. It's been awhile.
I just want to clarify a few things before I start.
Procedure (F) I take it that the plate control should
also be in the centre of the band I am adjusting ,
this is not mentioned in procedure. Also when
increasing exciter output to achieve a .400 amp.
reading on the grid meter, procedure (I) is this
correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate
current, procedure (J) is it a greatest dip possible
or just a slight dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
|
Re: L7 input coil ajustment
Ooops...sorry Paul....I wrote that very poorly and didn't pick it up in the proofread!
Actually, while nichrome parasitics?WERE removed from that amp (and I made my own copies of the originals to replace them), there were other mods in the input circuit that were also removed.? Paul's ESAC-Harbach all-in board was installed in the amp and it is THAT I was referring to.? I have?been a strong proponent of Paul's products for many years.? My statement was never meant to cause any misunderstanding?or harm.
Again....sorry Paul!
73 Peter VE7PS
On Mon, Jan 15, 2024 at 1:07?PM Paul Kraemer < elespe@...> wrote:
For the record? I have NO parasitic suppressors new or old for
ANY amplifier.
For the record.
Apology forthcoming?
Paul K0UYA
On 1/15/2024 2:53 PM, VE7PS wrote:
Howard:
I'll add two comments to David's instructions for adjusting
the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that correct
and it's the same procedure.
2)? While I would not personally recommend
adjusting the input tuning with high voltage applied...for
safety reasons...but?IF you choose to do so,
keep in mind you would also have to defeat the HV
interlock to do this with the lid off....which IS
necessary to reach the coils.
I recently did some work on an L-4B for a ham in Surrey,
BC.? I did the input tuning on his amp after undoing some
"magic nichrorme" mods and adding in some more modern ones
(Electronic Specialties).? Note the input tuning is very
broad, though perhaps due to aging of the caps, I did notice a
slight improvement on some bands.? As such, I am not in any
hurry to adjust the input tuning on my own amps, unless
perhaps the tubes get changed at some point.
Be careful!
73
Peter
VE7PS
Hey guys, I'm going to be doing
a input coil adjustment on my L7 amp. Eimac tubes are getting
very soft and I'm replacing them with RF Parts matched pair.
I've done this before and i'm very aware of safety procedures.
It's been awhile.
I just want to clarify a few things before I start. Procedure
(F) I take it that the plate control should also be in the
centre of the band I am adjusting , this is not mentioned in
procedure. Also when increasing exciter output to achieve a
.400 amp. reading on the grid meter, procedure (I) is this
correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate current,
procedure (J) is it a greatest dip possible or just a slight
dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
|
Re: L7 input coil ajustment
For the record? I have NO parasitic suppressors new or old for
ANY amplifier.
For the record.
Apology forthcoming?
Paul K0UYA
On 1/15/2024 2:53 PM, VE7PS wrote:
toggle quoted message
Show quoted text
Howard:
I'll add two comments to David's instructions for adjusting
the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that correct
and it's the same procedure.
2)? While I would not personally recommend
adjusting the input tuning with high voltage applied...for
safety reasons...but?IF you choose to do so,
keep in mind you would also have to defeat the HV
interlock to do this with the lid off....which IS
necessary to reach the coils.
I recently did some work on an L-4B for a ham in Surrey,
BC.? I did the input tuning on his amp after undoing some
"magic nichrorme" mods and adding in some more modern ones
(Electronic Specialties).? Note the input tuning is very
broad, though perhaps due to aging of the caps, I did notice a
slight improvement on some bands.? As such, I am not in any
hurry to adjust the input tuning on my own amps, unless
perhaps the tubes get changed at some point.
Be careful!
73
Peter
VE7PS
Hey guys, I'm going to be doing
a input coil adjustment on my L7 amp. Eimac tubes are getting
very soft and I'm replacing them with RF Parts matched pair.
I've done this before and i'm very aware of safety procedures.
It's been awhile.
I just want to clarify a few things before I start. Procedure
(F) I take it that the plate control should also be in the
centre of the band I am adjusting , this is not mentioned in
procedure. Also when increasing exciter output to achieve a
.400 amp. reading on the grid meter, procedure (I) is this
correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate current,
procedure (J) is it a greatest dip possible or just a slight
dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
|
Re: L7 input coil ajustment
Howard:
I'll add two comments to David's instructions for adjusting the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that correct and it's the same procedure.
2)? While I would not personally recommend adjusting the input tuning with high voltage applied...for safety reasons...but?IF you choose to do so, keep in mind you would also have to defeat the HV interlock to do this with the lid off....which IS necessary to reach the coils.
I recently did some work on an L-4B for a ham in Surrey, BC.? I did the input tuning on his amp after undoing some "magic nichrorme" mods and adding in some more modern ones (Electronic Specialties).? Note the input tuning is very broad, though perhaps due to aging of the caps, I did notice a slight improvement on some bands.? As such, I am not in any hurry to adjust the input tuning on my own amps, unless perhaps the tubes get changed at some point.
Hey guys, I'm going to be doing a input coil adjustment on my L7 amp. Eimac tubes are getting very soft and I'm replacing them with RF Parts matched pair.
I've done this before and i'm very aware of safety procedures. It's been awhile.
I just want to clarify a few things before I start. Procedure (F) I take it that the plate control should also be in the centre of the band I am adjusting , this is not mentioned in procedure. Also when increasing exciter output to achieve a .400 amp. reading on the grid meter, procedure (I) is this correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate current, procedure (J) is it a greatest dip possible or just a slight dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
|
Re: L7 input coil ajustment
Howard:? ?Please forgive me if this is a somewhat?disjointed note as I am still in the hospital but with the promise I will be home today after 4 days here.
The input circuit is to tune the input for the resonance of the input combined with the cathode driven section of the tubes.? That is essentially why the recommendation to return if the tubes?are replaced.? Since you are replacing the manufacturer, then it is good advice to do the tuning of the input RF circuits.
Note the instructions defeat the HV to the radio.? You may wish to just unscrew the HV lead from the power supply at the L7.? Insulate this connector as in this arrangement you will have plate voltage available.
While you have all the radio and stuff opened, you may wish to do the add to provide 10M capability to the unit.? There are instructions I am sure on this procedure on the internet.? It involves?removing the bar blocking the band switch from going one more position towards the right and adding two capacitors.? You can see this on the schematic.
There are several procedures to accomplish the tuning:
As Per The BOOK:
There does seem to be a confusion on the nomenclature for the metering that you are to watch.? Note also that the radio does not measure Plate current directly:? it measures the cathode?current as the voltage levels are less there.? So the two meters (as I remember) are the Grid Current, plate voltage, which the manual calls this the grid meter.? The other meter measures the plate amperes and this is the meter that the instruction (erroneously) calls the grid current meter.? You would be using this plate current meter for this method. Otherwise the instructions are clear as to what to do.? Using this method I have not turned up the input power so that I read .400 amperes?on the plate current.? For when I have done this, a lesser current was used and the tuning was ok.
Using AN? Antenna Analyzer Method:
With?the plate?voltage?disabled as the instructions?call for (or unscrewing the plate lead), place an antenna analyzer to the input.? You will need to have the unit on with the tubes installed.? The exciter will be needed to turn on the transmit function of the amplifier so keep the output power of the exciter at zero.? On the appropriate band, adjust the band coli for minimum SWR on the meter.
Using the unit as is without any power supply disable action:
A least desirable?method is to simply load the unit on a band and adjust the input coils so that you are getting max power to the tubes.? You do not have to run this at high power either from the plate voltage side or the exciter side.? Be careful, you have plate voltage inside the unit; that is why it is the least desirable?method.
I have done all three and each more or less arrives at the same tuning.? For each band, you should set the exciter frequency for the middle of the band you are going to adjust.? Use only the power needed to get a reliable reading on the meters.
Of all the methods, I use the input antenna analyzer.? Since the whole reason for the adjustment is to adjust the input circuits to the point of resonance (lowest SWR), then you may wish to try this.
Each method works.? Be clear, be safe and Good Luck.
David Assaf III W5XU, VP8RXU ?
Hey guys, I'm going to be doing a input coil adjustment on my L7 amp. Eimac tubes are getting very soft and I'm replacing them with RF Parts matched pair.
I've done this before and i'm very aware of safety procedures. It's been awhile.
I just want to clarify a few things before I start. Procedure (F) I take it that the plate control should also be in the centre of the band I am adjusting , this is not mentioned in procedure. Also when increasing exciter output to achieve a .400 amp. reading on the grid meter, procedure (I) is this correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate current, procedure (J) is it a greatest dip possible or just a slight dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
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Re: Solid State 2B Receiver
I was at the FDIM QRP forum and had hands on with this receiver. The video doesn¡¯t do it justice.
mike wb8vge
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W4OP describes his receiver in this youtube video:
Bob/WB0AUQ
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Re: Solid State 2B Receiver
Great, thanks!
--Ed, N3CW--
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Re: Solid State 2B Receiver
W4OP describes his receiver in this youtube video:
Bob/WB0AUQ
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Re: Solid State 2B Receiver
I bet the owner of PAR knows where that board design came from and would be willing to share.
John k5mo
On Mon, Jan 15, 2024 at 9:53?AM Ed G < ed.n3cw@...> wrote: Folks,
???? While browsing the PAR Electronics website, I came across this brief post of a homebrew solid-state 2B receiver:
Anyone here know more about this interesting project?
--Ed, N3CW--
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Re: Solid State 2B Receiver
Thanks, Ed. I only wish I possessed the skills¡ ? joseph n. graif k4jng ?
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From: [email protected] < [email protected]> On Behalf Of Ed G Sent: Monday, January 15, 2024 9:53 AM To: [email protected]Subject: [DRAKE-RADIO] Solid State 2B Receiver ? Folks,
???? While browsing the PAR Electronics website, I came across this brief post of a homebrew solid-state 2B receiver:
Anyone here know more about this interesting project?
--Ed, N3CW--
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Folks,
???? While browsing the PAR Electronics website, I came across this brief post of a homebrew solid-state 2B receiver:
Anyone here know more about this interesting project?
--Ed, N3CW--
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Jim Shorney
David