Re: 6HS6 Price and Availability
Gary, I live in Tucson, and I've been buying stuff from Elliott Electronic Supply for almost 50 years. And they are still there in the same place!
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It's kind of amazing to me also but a welcome resource that I want to keep around, so if any of you need something they are on-line and will ship it out to you. When I went in there yesterday I saw 5 guys working behind the counter -- that they have that much business to employ so many people is doubly amazing. Much of the stock now is the usual Chinese products you can buy on eBay or Amazon, but the convenience of it being 20 minutes away is worth using them for me.
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And next door they have Elliott Surplus which seems to be a rotating hamfest of consignment items, it's always different each visit. Quite a few boatanchor receivers in stock, as if I needed any more projects. Last month they had an RME-70 and now a National NC-2-40D, among many others. It's worth a visit if you're ever passing through on I-10.
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Dave
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Re: Using the PLJ-6LED digital display with the R4C
Hi Mark.? With the T4X connected to the injection line, are you able to get an accurate and stable readout on the counter on 10 and 15 meters?? I see you're in Doylestown - used to ride the bicycle to Doylestown through Rogues Hollow.? I was located in Jackson Township at that time.
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73, Floyd - K8AC
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Re: 6HS6 Price and Availability
YES!
W7GZ,? where in the world(and which world) are you?? Maybe you are a time traveler??? hi hi...
73,
Gary
WB6OGD
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Good morning?
i'm interested if the ac-4's are recapped....
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Let me know your best price
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Paul IK1QHB
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please via email at ik1qhb@...
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Re: Using the PLJ-6LED digital display with the R4C
Floyd,
The width of the display has not changed since I wrote the article many years ago. The unit does not touch the front panel but is mounted next to the inside panel behind the display plastic window.? Since it is mounted some distance from the front panel window, you can easily see the first and last digit by adjusting your viewing angle by moving your head left or right. I have my displays positioned slightly more towards the center of the radio giving preference to the last digit. I've installed maybe 10-15 of these in this manner and have had no issues other than I have had to play around with the value of the coupling cap. Using a scope I monitored the INJ level and used a cap that did not load it down. I've not had to use a buffer amp, but that would be a good fix and probably eliminate having to play around with cap values.?
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Good luck and be interested in what you end up having to do to fix yours.?
73's,
Mark, WB0IQK
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Re: 6HS6 Price and Availability
The most remarkable part of this, is that you have a local electronics store that stocks tubes!? Thanks for the report.
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John K5MO
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Hello Earl. Thank you for clarifying that! I agree with your observation that above 10M, RF gain is far less important! In fact not really needed much. For FM mode... zero.
I asked if you were using "electricity" in a lighthearted way 100%. I monitor VHF/UHF quite a lot and I too NEVER need to touch the RF gain! For low band SWL, 120 meters - 13 meters I do use it as needed depending on the time of year and conditions/mode. S/N on the SWL bands is
often a struggle, and fiddling with receive antenna's, RF gain, is key especially on 120m-41m. Yeah, there is life outside the "honey baked ham bands".
J
On Wed, Jan 8, 2025 at 03:13 AM, Joseph K7CBR wrote:
Are you still using electricity?
On Wednesday, January 8, 2025 at 05:19:40 PM EST, N3 EG <n3eg@...> wrote:
The RF Gain control has always been the most useless thing to put on a radio.? It's like a high/low switch on a vacuum cleaner, which should be called "Clean/Less Clean."? In the case of HF radios, it should be called the Ignore Weak Signal Stations And Screw Up Your S-Meter Reading Control.?
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I've never found a good reason to use it in at least 52 years of HF listening, and it's totally useless on 10 meters and up.
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Re: 6HS6 Price and Availability
>¡±I remember in the 70s hams experimenting with various tubes to "soup up" the front ends of their radios. These new types had higher transconductance and lower noise than what the factory supplied -- 6BZ6/6CB6/6GM6/6HS6, etc., and were all sharp-cutoff pentodes.¡± ? Several years ago, I purchased Electric Radio Magazine¡¯s 75A-4 Modification Compendium.? It¡¯s 240 pages of modifications in a 3-ring binder, many of which are related to optimizing the RF and mixer stages.? Collins chose a 6DC6 for the 75A-4¡¯s RF amp, although I believe 75A-4 production in 1955 may have pre-dated the 12BZ6 and 6HS6.? ? As Dave points out, most mods were primarily focused on noise and transconductance.? However, Bob Stankus, W2VCZ, heavily modified his 75A-4, beginning with a 6GM6 in the RF stage, followed by 7360s in the IF stages.? I believe his is one of the few mods that seriously consider dynamic range and front-end overload.? His modification is one of several in the Compendium.? ? Paul, W9AC
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Re: 6HS6 Price and Availability
you guys seen this?
Lee, w0vt
_skw=10+pc+small+PCB+for+CMC+EIZZ+7+pins+tube+socket+adapter+7+pin+6Z4+6X4+6J1+6X4&itmmeta=01JH4R5JHHM35XZ770SEXGXNEY&hash=item41e46a6e90:g:AXgAAOSw4aZbH0-N&itmprp=enc%3AAQAJAAABMHoV3kP08IDx%2BKZ9MfhVJKlv%2BlvtfMcQEgaCtq6PEiXweii%2B1NhAyPxF97xLiUzHy2fFv5C9SMvyt5px%2BrLz45F1JNbnLID8qrvX4vqEJJkNIE9eT7nY4%2BtiAAHLxugfXxQLy2egBGJtEj6dV8eHlB%2BX9XJ486Ten90LuJLGLNrBmgj7MH29KgWfoRRiLIpUpLrLZCoGqwvq3M3G2697N%2FvX2U1rPIxBbmygnFqWqdeeTRQZw4tfU88dwabARBxpixG9v4LEq5m641Qq7qSsudiE9qtGCRSYdJAO%2B9Ju3vBNs%2BKKXztBb3cwoy3iPCPR7ObxCKcQugTuxRPhjDpwDkRP2IuGt0P3u7dmBRM6SbapF%2Bs4wEm2etOXZ0ba%2B5uqW5z2GpoKuD%2FWvyxRmf0JtYU%3D%7Ctkp%3ABk9SR_ColpiJZQ
On 1/8/2025 3:50 PM, Gary WB6OGD via
groups.io wrote:
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It is pretty easy to make a solid state mixer. Unlike
amplifiers, that need just a certain amount of amplification,
extra AVC inputs, etc., mixers are
basically non-linear choppers.? They just need enough gain to
chop and enough voltage tolerance for the circuit they are in.
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My very first experiment was a J-310 FET(the only FET I had)
plugged into the R-4A Pre-mixer socket.? I only had to
disconnect the +150V plate supply resistor and hook it to about
18VDC(?).? Worked fine though hooking it to the T-4X and
selecting XMTR control might have blown it.
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I researched more (stole designs and modded) and now have a
plug in tube replacement.? Works great.
Attached is what I think I am running now.? I also attached a
6AU6 replacement from the Collins site.
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Beats trying to buy expensive, possibly bad old tubes.? YMMV.
My 6HS6 is now safe and part of my 401K IRA.. hi hi...
73,
Gary
WB6OGD
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Re: AFG/RFG controls R4C (W1ES)
On 2025-01-08 17:18, Steve Wedge, W1ES/4 via groups.io wrote: Funny thing is, lately, my TR7 is the rig that most benefits from
lowering the RF gain a tad. Lots of popping on fast AVC, otherwise.
The A's and B's areen't as bad. The C is in between... *** My latest boat anchor project REALLY wants the RF gain set down. It's a Signal/One CX7A. Signal One messed up the injection to the product detector, and if you have the RF gain all the way up, it distorts. Voices sound harsh. There's a fix - you change one resistor. Waiting for me to get a round tuit. - Jerry, KF6VB
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Re: 6HS6 Price and Availability
I meant to say that my memory the 6AU6 has a reputation for being mechanically noisy. It is also a sharp cut-off pentode, not good for use with AVC circuits. However, a sharp cutoff tube can be used with some tailoring of bias, as in the 51J series which uses the 6AK5.
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On 1/8/2025 8:22 PM, Richard Knoppow via groups.io wrote: ?? The 6BA6 is fairly common as an RF amp, see for instance the SP-600
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Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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Re: 6HS6 Price and Availability
The 6BA6 is fairly common as an RF amp, see for instance the SP-600 and other receivers. It has good dynamic range which may be more important than noise level. It is essentially a variable mu version of the 6AU6. By memory the 6HS6 has a higher Gm than the 6BA6, which would make it quieter.
A very long time ago I did some experimenting with RF amps in an old Super-Pro which was my test bed. Tried many exotic tubes and different circuits including a cascode amp. Wound up using the 6BA6 due its ability to handle a wide dynamic range.
When I bought the receiver the entire RF section had been rebuilt by someone using dual triodes. It sort of worked but I decided to try other things.
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On 1/8/2025 5:19 PM, Paul Christensen via groups.io wrote: Drake¡¯s R4 series RF amp evolution is interesting.? It began with a 12BZ6 in the original R4/R4A, changed to a 6HS6 in the R4B, ending with a 6BA6 in the R4C.? The latter is commonly found in many IF circuits, including Drake but not too often used as the 1^st RF amp.? Can anyone guess as to Drake¡¯s impetus for the change? ?Seems like all three tube types were available at the beginning of R4 production.
Paul, W9AC
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Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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Re: 6HS6 Price and Availability
Paul raises a very interesting question, What prompted the evolution of device selection for RF amp and 1st mixer in Drake's receivers?
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12BZ6/6AU6 -> 12BZ6/6HS6 -> 6HS6/6HS6 -> 6BA6/6EJ7? ? if I have the sequence correct.
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ChatGPT tells me they went with 40673 MOSFETs at some point later on, but I doubt any of those ended up in the R-4x line. I'll be corrected if so.
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I'll throw out a hypothesis:
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The initial R-4 design was likely based on what they were used to using in earlier product lines. Getting the new receiver out the door quickly and into the market to support the company was probably very important.
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I remember in the 70s hams experimenting with various tubes to "soup up" the front ends of their radios. These new types had higher transconductance and lower noise than what the factory supplied -- 6BZ6/6CB6/6GM6/6HS6, etc., and were all sharp-cutoff pentodes. No doubt the engineers at Drake took notice of this and did their own research and experimentation, developing lower-noise, more sensitive receiver front-ends for weak signals. All well and good, until...
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Customers started complaining about IMD and front-end overload in crowded contest conditions. Probably around this time test equipment of high enough quality to measure these effects also became available. Engineers were sent back to the drawing board to see what could be done to fix that issue. Reaching back into the dusty pages of some old data books, someone remembered the old, reliable 6BA6, which had been used in TV receivers for years. It's a remote-cutoff pentode with lower transconductance, but better dynamic range capability than the high sensitivity tubes. The resulting design was a good compromise between sensitivity and IMD. I haven't heard of Drake front-ends becoming unstable, but almost certainly the 6BA6 was a more stable tube than the ones with higher transconductance.
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I wasn't present at Drake, I have no first-hand or historical knowledge, nor a deep technical understanding of receiver design, and all of this could be complete rubbish. But I toss it out to generate a discussion.?
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Dave
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I had left the rig powered on overnight after working a number of guys.? Came back the next morning and the rig was showing no life.? Fuse was popped.
With the rig on the bench, I could turn on the power and after maybe 20-30 seconds, I could see an arc starting on the tune cap. On close examination of the tune cap, 4 of the plates in one section had arced enough to have slightly melted away a bit of the plates on the fixed half.
Repaired the damage and checked the cap out with the HV leakage tester - looked good to about 1500V or so. Put it all back together and almost put it back on the shack shelf when it occurred to me.? With the rig sitting at idle, there should be NO voltage across the tune cap.? That assumes the coupling cap was working properly in it's DC-block role.? I replaced the 2700pf/2KV with a 4700pf 3KV ceramic I had in the junk box and then put it back on the shack shelf for check out.
Tested the old coupling cap and the leakage even at 1KV was only slightly higher than the new Vishay ceramic part I had put in as the replacement.? Even warmed it up with the heat gun - no change.? This is pretty weird as I almost never see ceramics leak but maybe they do.
The rig is working fine now although power is about 1/3 to 1/2 what I would expect.? The unloaded HV was OK when it was on the bench and I'm thinking there may be another problem.? I can't imagine that a leaking coupling cap, arcing through the tune cap, would damage the finals though.
Wanted to toss that scenario out and see if anyone on the reflector may have run into a similar case in the past.
HNY!
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73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
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Re: 6HS6 Price and Availability
Thanks for this no-guesswork essay, Steve. ?Maybe when time avails, quantitative testing will be done and published.
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73, Michael, N4KZO
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Re: 6HS6 Price and Availability
Roger that, John.
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73, Michael, N4KZO
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Re: 6HS6 Price and Availability
Thank you, Gary: a little good engineering ¡ª love it.
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73, Michael, N4KZO
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Re: 6HS6 Price and Availability
Good work, Dave. ?Thank you for your efforts in experimental tests to resolve this drama: learning, learning, we never stop learning
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73, Michael, N4KZO
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Re: 6HS6 Price and Availability
Thank you, Kim. ?Doing a little looking around, I¡¯ve found bunches and grunions of NOS 6AH6 tubes: say $3 - $4 EACH. ?You answer which immediately comes to my mind, as to why the 6HS6 was chosen by Drake engineering. ?With the present atmospheric noise level, the 6AH6 should work fine, if present; when it gets quiet again, I can check use of the 6AH6 as an experiment as I think I have all 6HS6¡¯s. ?But, as Peter has elucidated, we don¡¯t need to concerned; I¡¯m working on getting a B-line going and haven¡¯t assessed a need, but I¡¯m sleeping easy: a good lesson.
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73, ?Michael, N4KZO
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Re: 6HS6 Price and Availability
Good job, Peter. ?Good lesson for me. Thank you.
zzzzzzzzzzzzzzzzzzz
73, Michael, N4KZO
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Floyd - K8AC
Gary WB6OGD
Paul Christensen