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Fair Radio is still blowin’ and goin’.
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73,
Bill
KJ5BNE
- - - - - - - - - - - - - - - - - - - - - -?
Bill Blodgett
Arlington, Texas
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On Jan 16, 2024, at 11:53?AM, myteaquinn via groups.io <myteaquinn@...> wrote:
I believe that Fair Radio has closed.
myteaquinn,?west of Cleveland
On Tuesday, January 16, 2024 at 12:46:10 PM EST, James Barrie <barrie43@...> wrote:
Check Fair Radio, Lima Ohio
On Sat, Jan 13, 2024, 12:28 mike bryce <
prosolar@...> wrote:
Hi, everyone,
Don’t want to start a debate, but I’m in the need of a couple of tubes. Who’s the go to guy for buying tubes?
Some of the old links I have are now dead ends
mike wb8vge
Please check with Foster Paulis, W4HCX, in Pahrump, Nevada. Foster has bays full of tubes of all varieties and sizes. You can reach him at w4hcx@... or by phone at (775) 751-5389. Good luck and 73, Craig, KL7H
|
I believe that Fair Radio has closed.
myteaquinn,?west of Cleveland
On Tuesday, January 16, 2024 at 12:46:10 PM EST, James Barrie <barrie43@...> wrote:
Check Fair Radio, Lima Ohio
On Sat, Jan 13, 2024, 12:28 mike bryce < prosolar@...> wrote:
Hi, everyone,
Don’t want to start a debate, but I’m in the need of a couple of tubes. Who’s the go to guy for buying tubes?
Some of the old links I have are now dead ends
mike wb8vge
|
Check Fair Radio, Lima Ohio
On Sat, Jan 13, 2024, 12:28 mike bryce < prosolar@...> wrote:
Hi, everyone,
Don’t want to start a debate, but I’m in the need of a couple of tubes. Who’s the go to guy for buying tubes?
Some of the old links I have are now dead ends
mike wb8vge
|
Great places to start looking. I appreciate your thoughts.
Joe ki5o?
|
Joe,
It sounds like either you have dirty bandswitch on the?80m position or a bad crystal (14.6).?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Tue, Jan 16, 2024 at 10:19, Joe KI5O < ki5ojoe@...> wrote: Good morning.
Late night in the shack and was listening to the bands with the B-line twins. Everything is working well with exception of the R4B on 80m.
Generally I run the twins with the proper injections cable with the T4XB setting of XVCR driving the injection to the R4B. All bands working correctly (including 80m) and providing proper output to the frequency counter as well.
When running the R4B as separate, RCVR, and also with the T4XB turned off, I get nothing on 80m. For 40m and all other bands, the preselector peaks the signal, proper frequency shows on the counter, and everything else works.
On 80m, with the R4B as master or separate I am not receiving signal, preselector doesn't affect peaks, and no output to the frequency counter. Also if I move the preselector close to 12 o'clock it will start to pickup signal close to the WWV 5Mhz but it doesn't align with the VFO dial.
Before I pop the hood, any thoughts? Before I got the T4XB I used this R4B with another TX. Was working fine at that time, and I haven't been doing anything inside the case since then.
Thank you for any thoughts, if you need any other information please let me know.
Thank you
Joe ki5o?
|
A couple of each. one set for the radios going through repairs, and set to keep in stock.
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
J e e p
o|||||||o?
A man with one clock knows what time it?is. A man with two clocks is never sure.
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Show quoted text
I have a bunch of all three new in boxes.
How many of each do you need?
Gary
|
I have a bunch of all three new in boxes.
How many of each do you need?
Gary
toggle quoted message
Show quoted text
On Jan 14, 2024, at 8:40?AM, mike bryce <prosolar@...> wrote:
I’m looking for 6EW6, 6EA8. 12AU7 tubes …
Maybe some more
mike wb8vge
I acquired over 1000+ tubes that a SK ham who was a vintage radio fanatic.? I have them all inventoried but haven't tested everyone.? Let me know what you need.??
Myron KL7YY Colorado Springs, CO? ? On Sat, Jan 13, 2024 at 10:28?AM mike bryce < prosolar@...> wrote:
Hi, everyone,
Don’t want to start a debate, but I’m in the need of a couple of tubes. Who’s the go to guy for buying tubes?
Some of the old links I have are now dead ends
mike wb8vge
|
Good morning.
Late night in the shack and was listening to the bands with the B-line twins. Everything is working well with exception of the R4B on 80m.
Generally I run the twins with the proper injections cable with the T4XB setting of XVCR driving the injection to the R4B. All bands working correctly (including 80m) and providing proper output to the frequency counter as well.
When running the R4B as separate, RCVR, and also with the T4XB turned off, I get nothing on 80m. For 40m and all other bands, the preselector peaks the signal, proper frequency shows on the counter, and everything else works.
On 80m, with the R4B as master or separate I am not receiving signal, preselector doesn't affect peaks, and no output to the frequency counter. Also if I move the preselector close to 12 o'clock it will start to pickup signal close to the WWV 5Mhz but it doesn't align with the VFO dial.
Before I pop the hood, any thoughts? Before I got the T4XB I used this R4B with another TX. Was working fine at that time, and I haven't been doing anything inside the case since then.
Thank you for any thoughts, if you need any other information please let me know.
Thank you
Joe ki5o?
|
Bob thank you for the assistance, cleaning up the potentiometer wiper and coil seems to have resolved the issue.
Joe ki5o
|
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
|
Craig KL7H
Jim Shorney
David