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(Since this is a diversion from the original topic (SR-500 Tornado), I assigned a new topic.)
Thanks, Bob and Walt,
Since the SR-160 and SR-150 both use 12DQ6B finals, wouldn't the sockets be the same and the same rewiring of sockets be required?? On further examination of the 2 radios' schematics, I see that the circuits around the finals are a little different, so maybe there would be some additional changes needed there, too.?
I agree that the potential performance benefit would be small.? That half of an S unit was, apparently, sufficient for some hams to buy an SR-500 instead of an SR-160 a several decades ago.? Maybe it was just a bigger number on the front panel or the invoice.?
Cheers
Halden
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Hi all,
As I recall, there was a bit of a
"horsepower" (er, Peak Envelope Power - PEP) thing going on during
the late 60s and 70s where manufacturers focused on the 'peak'
power (PEP) rather than average power or CW power. It was also a
time when TV sweep tubes were inexpensive and if pushing the power
a bit resulted in a shorter tube life, so be it. The plate
dissipation of the 6DQ6/12DQ6 is only 18 watts, so figuring a
typical efficiency of 50% to 60% for class AB1 operation, the "key
down" power would be limited to about 70 watts input for a pair of
tubes. Fortunately most ham operation is not continuous key down
and we are able to get away with more peak power. One common
assumption for SSB operation is that the peak power (PEP) is about
twice the average power (the duty cycle is about 50%). Given this,
a pair of these tubes could conservatively be used at about
140-150 watts input without stressing the tubes. The intended
application for the sweep tubes as horizontal output tubes in TV
requires high peak power (plate current), while the average
dissipation is significantly lower. I have attached a small file
comparing the ratings of several of the sweep tubes used in ham
and CB equipment during this time frame. Note that the largest
plate dissipation is about the same as the venerable 6146B at
around 30 watts. The difference is that the 6146 is designed for
continuous duty operation vs. low duty cycle operation. A number
of hams have been bit by not being aware of power requirement when
using modes that are in fact 100% duty cycle such as RTTY and (I
think) FT-8.
I suspect the use of PEP was mostly a
marketing statement intended to provide a simple number that could
be used to compete against other manufacturers using PEP in their
advertising, much as we see the same thing today in marketing 1kw
amplifiers vs 1.5kw amplifiers. The difference is less than 1/2 of
an "S" unit but, golly, its 50% more power.
Anyhow, almost all of these tubes are
getting harder to find and more expensive as the existing supplies
gradually dry up...
Bob,? K7DYB
On 2/23/2025 1:36 AM, HF via groups.io
wrote:
toggle quoted message
Show quoted text
(Since this is a diversion from the original topic (SR-500
Tornado), I assigned a new topic.)
Thanks, Bob and Walt,
Since the SR-160 and SR-150 both use 12DQ6B finals, wouldn't
the sockets be the same and the same rewiring of sockets be
required?? On further examination of the 2 radios' schematics, I
see that the circuits around the finals are a little different,
so maybe there would be some additional changes needed there,
too.?
I agree that the potential performance benefit would be
small.? That half of an S unit was, apparently, sufficient for
some hams to buy an SR-500 instead of an SR-160 a several
decades ago.? Maybe it was just a bigger number on the front
panel or the invoice.?
Cheers
Halden
|
We shouldn't loose sight of the original topic, which was the use of the 6DQ5
in place of?the 8236. The 6DQ5 has a plate dissipation of 24?watts and transconductance of 10.5K. The 6DQ6 is 18 watts and 7.3K.
Two interesting tubes on the chart which I have not considered or explored are the 6JE6 and the 6JF6, 30 watts and 10.7K. I think I have some in my treasure boxes, may have to investigate them.
Has anyone played with either of these tubes?
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.
|
On Mon, Feb 24, 2025 at 05:28 AM, Robert Kembel wrote:
.........Note that the largest plate dissipation is about the same as the venerable 6146B at around 30 watts. The difference is that the 6146 is designed for continuous duty operation vs. low duty cycle operation. A number of hams have been bit by not being aware of power requirement when using modes that are in fact 100% duty cycle such as RTTY and (I think) FT-8.
?
?
Bob,? K7DYB
?
The comparison of horizontal sweep tubes vs the 6146 should probably include mentioning the fact that the vacuum tube manufacturers did not use CCS/ICAS ratings for nearly all the? sweeps (some exceptions)? because they weren't tested for those types of service. (that of course did not mean they wouldn't work!)
?
The CCS? plate dissipation rating of an RCA 6146/6146A is? 20W.? (27W for a 6146B/8298A)?
?
?
Collins, Heath, Hallicrafters (to name a few) designed their transmitters using the 6146 to put out about 100W (staying approx? within the ICAS ratings [25w ea] for a pair of them
?
For comparison, the plate dissipation of a 6JB6 horizontal sweep tube (used in the Drake T-4X, TR-3[12JB6], TR-4, TR-6, TC-6) is 17.5W? (A whole 2.5W difference vs the 6146)
?
Some had more dissipation.... The 6DQ5 for example in our beautiful HT-44's,? has 24W plate dissipation etc....
?
That would make the 6DQ5 "better" than a 6146/6146A I would think.
?
Now having said that,? the original 6146 had 20W CCS dissipation, what would the 6DQ5 have if it was rated CCS?
?
I would submit that because horizontal sweep tube service actually is "CONTINUOUS"? (I.E, your TV was turned on in the morning and maybe not turned of until 18-24hrs later? (OR not turned off at all!!)? (wake up in the wee hrs of the morning to "snow" on the screen!!)
?
That's about as continuous as it gets!.....so the 6DQ5 would have 4w more dissipation vs a "CCS" 6146/6146A
?
Now, I will concede that Hallicrafters, Drake, Swan and all the others did indeed design and suggest operating sweeps at much higher peak power than would even be possible with? 6146s and included cautions to not "key-down" for too long...... But,? I don't think 6146's would fare any better than any sweep tube if abused at greatly higher power levels.
?
?
?
Now to get back to the original (opinion) discussion, I really am with a few others here in that increasing the power output of an SR160 or an SR150? (even double [3dB])? is simply not worth the effort.
?
Get a linear amplifier.
?
By the way, I am looking for a REALLY nice SR-150 to put next to my Loudenboomer if someone wants to part with one! (It cannot look like it was stored in someones leaky-roof garage though)
?
?
?
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
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On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:
We shouldn't loose sight of the original topic, which was the use of the 6DQ5 in place of?the 8236.
?
?
?
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.
?
I would tend to agree.
?
If I am not mistaken,? the SR 500 in good repair and alignment would presumably do somewhere around 250-275W PEP output based on operating it at 500W PEP input.
?
My HT44 with the stock PS-150-120 seems to work well at about 150W PEP output.
?
The difference between 150w (approx 52dBm) and 275W (54.4dBm) is not even 3dB total making it an essentially un-detectable difference on the other end.
?
And even if you're going from 100W to 300W (50-54.8dBm) it's less than a 5dB difference, which is also not very significant on the other end.? To me, it doesn't really seem worth it to "butcher" the radio to make it happen.?
?
Most of the fun I have using my HT44, HT32B and? SR400 (and even the HT33 Mk I, HT45 Mark IIA)? is the simple joy of operation in good band conditions.? When I mention I am using them, it generates all sorts of fun conversation about them vs how strong the signal is!
--
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
|
And for proof of the power theory (fact) I just completed a cw Q to Wake Island over the weekend accidentally driving my Acom 1500 which was till tuned for 15M while having the K4 set for 100W drive on 12M. Made the contact in one call and then noticed I had not thrown my antenna switches to go 'round the amp. My forward power with this mixup was 3W.
Confirmed this by going up freq and keying and sure enough, my inline wattmeter was barely moving attesting to genuine QRP. I received a 559 from Wake.
The lesson, don't need to burn the rig for a few more watts.
Ed, WA9GQK
On Monday, February 24, 2025 at 03:40:49 PM CST, Rick W7IMM via groups.io <myr748@...> wrote:
On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:
We shouldn't loose sight of the original topic, which was the use of the 6DQ5 in place of?the 8236.
?
?
?
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.
?
I would tend to agree.
?
If I am not mistaken,? the SR 500 in good repair and alignment would presumably do somewhere around 250-275W PEP output based on operating it at 500W PEP input.
?
My HT44 with the stock PS-150-120 seems to work well at about 150W PEP output.
?
The difference between 150w (approx 52dBm) and 275W (54.4dBm) is not even 3dB total making it an essentially un-detectable difference on the other end.
?
And even if you're going from 100W to 300W (50-54.8dBm) it's less than a 5dB difference, which is also not very significant on the other end.? To me, it doesn't really seem worth it to "butcher" the radio to make it happen.?
?
Most of the fun I have using my HT44, HT32B and? SR400 (and even the HT33 Mk I, HT45 Mark IIA)? is the simple joy of operation in good band conditions.? When I mention I am using them, it generates all sorts of fun conversation about them vs how strong the signal is!
--
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
|
Last year I turned the rig on and the band sounded in really poor shape but there was a station calling CQ and I answered and worked him. Afterwards I realized why the band was quiet. I was on the dummy load and the other station was about 1500 miles away! Who needs QRO??
73 Don ve3ids?
On Mon., Feb. 24, 2025, 6:50 p.m. edward schumacher via , <eddiewa9gqk= [email protected]> wrote:
And for proof of the power theory (fact) I just completed a cw Q to Wake Island over the weekend accidentally driving my Acom 1500 which was till tuned for 15M while having the K4 set for 100W drive on 12M. Made the contact in one call and then noticed I had not thrown my antenna switches to go 'round the amp. My forward power with this mixup was 3W.
Confirmed this by going up freq and keying and sure enough, my inline wattmeter was barely moving attesting to genuine QRP. I received a 559 from Wake.
The lesson, don't need to burn the rig for a few more watts.
Ed, WA9GQK
On Monday, February 24, 2025 at 03:40:49 PM CST, Rick W7IMM via <myr748= [email protected]> wrote:
On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:
We shouldn't loose sight of the original topic, which was the use of the 6DQ5 in place of?the 8236.
?
?
?
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.
?
I would tend to agree.
?
If I am not mistaken,? the SR 500 in good repair and alignment would presumably do somewhere around 250-275W PEP output based on operating it at 500W PEP input.
?
My HT44 with the stock PS-150-120 seems to work well at about 150W PEP output.
?
The difference between 150w (approx 52dBm) and 275W (54.4dBm) is not even 3dB total making it an essentially un-detectable difference on the other end.
?
And even if you're going from 100W to 300W (50-54.8dBm) it's less than a 5dB difference, which is also not very significant on the other end.? To me, it doesn't really seem worth it to "butcher" the radio to make it happen.?
?
Most of the fun I have using my HT44, HT32B and? SR400 (and even the HT33 Mk I, HT45 Mark IIA)? is the simple joy of operation in good band conditions.? When I mention I am using them, it generates all sorts of fun conversation about them vs how strong the signal is!
--
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
|
That Dummy is not so dumb? -- don??? va3drl
|
For several years during the 1970s my only rig was a Heath HW-7 running
3 watts with which I worked over 30 states on 40 CW using an attic
dipole. Lots of fun. You can't work everyone you hear with QRP, but
patience helps.
73,
Maynard
W6PAP
toggle quoted message
Show quoted text
On 2/24/25 15:50, edward schumacher wrote: And for proof of the power theory (fact) I just completed a cw Q to Wake
Island over the weekend accidentally driving my Acom 1500 which was till
tuned for 15M while having the K4 set for 100W drive on 12M. Made the
contact in one call and then noticed I had not thrown my antenna
switches to go 'round the amp. My forward power with this mixup was _3W_.
Confirmed this by going up freq and keying and sure enough, my inline
wattmeter was barely moving attesting to genuine QRP. I received a 559
from Wake.
The lesson, don't need to burn the rig for a few more watts.
Ed, WA9GQK
On Monday, February 24, 2025 at 03:40:49 PM CST, Rick W7IMM via
groups.io <myr748@...> wrote:
On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:
*We shouldn't loose sight of the original topic, which was the use
of the 6DQ**5 **in place of?the 8236. *
**
**
*Walt Cates, **WD0GOF*
*_ <> _*
*A majority of acceptance is not proof of correctness. *
*
<>**
*
I would tend to agree.
If I am not mistaken,? the SR 500 in good repair and alignment would
presumably do somewhere around 250-275W PEP output based on operating it
at 500W PEP input.
My HT44 with the stock PS-150-120 seems to work well at about 150W PEP
output.
The difference between 150w (approx 52dBm) and 275W (54.4dBm) is not
even 3dB total making it an essentially un-detectable difference on the
other end.
And even if you're going from 100W to 300W (50-54.8dBm) it's less than a
5dB difference, which is also not very significant on the other end.? To
me, it doesn't really seem worth it to "butcher" the radio to make it
happen.
Most of the fun I have using my HT44, HT32B and? SR400 (and even the
HT33 Mk I, HT45 Mark IIA)? is the simple joy of operation in good band
conditions.? When I mention I am using them, it generates all sorts of
fun conversation about them vs how strong the signal is!
--
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
|
Rick W7IMM,
If you would please contact me offline.
73/Randy WN9D
|
Robert Kembel
waltcates
Rick W7IMM
Don VE3IDS
don Root