There's one thing that maybe should be kept in mind about what people may be using to drive their L-7 or L-4 /L-4B when it comes to ICOM transceivers. ??

I'm not sure that everyone who uses ICOM radios are using the IC-7600/7610 or the even IC-7800/7850/51's? for that matter.

A very large portion of them have the IC-7300 transceiver.? I don't know the actual numbers but it seems A LOT of people I talk to these days are using what one amateur I know calls the "Belly-Button" radio? (everybody has one!)

Directly connecting the IC-7300 to an L-7 or L-4 could eventually damage/destroy the send relay. Hence the "Warning" from the manual.

The below statement is taken directly from the ICOM 7300 instruction manual:
The IC-746, 7410, and others are similar

?WARNING!
??The maximum signal level of the [SEND] jack is 16 V/0.5 A DC. Use an external unit if your non-Icom linear amplifier requires a control voltage and/or current greater than specified.


I also found that my L-4B in stock configuration could not be "keyed" directly with the IC-705 or my IC-M802. Both of which use "open collector" type keying. (For the IC705, I suppose it should probably be called "open? drain" FET keying etc...)

The IC-M802 easily drives the L-4B to 1000W or more output.

Now,? before anyone laughs at? using an IC-705 to drive the L-4B, it's 10W output drives my L-4B to about 250W
(and having said that, I normally use the 705 to drive a Mercury III to about 1200-1300w on 160-40.? It's a little less above ...)

Since my C-line only drives the L-4B to around 1300w, it's a tad over a 7db difference when driving with the IC-705.

But I MUST use a keying interface with both the M802 and 705.

I'm currently using a CRYDOM MPDCD3 (opto-isolated) solid state "relay"? with a pair of 3-vdc series lithium batteries.


Of particular note is the max turn-on/turn-off time of? only 0.1ms .....? There are many other DC (and AC)? controlled solid state "relays" that will control DC and AC and switch with similar times

You could use "accy port -supplied" DC voltage for it.? The IC-705 doesn't have DC voltage available in the "SEND" line so I used the 2x3v battery holder for maximum isolation. (it only draws about 4ma from the batteries during "key-down")

Just another way to do it if desired and it works for just about any amp.


--

73/Rick

W4XA
*Every post is created using Linux

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BUT PLEASE start a new email with the proper subject Bob.

Thanks
Jim W7RY

Bob, you're in the right place!

Question away!

John

On Wed, Jan 10, 2024 at 1:33?PM Bob KD6GNB <behrhorn@...> wrote:

Well hi y’all?

I see the discussion is about Drake HF radios I was directed here ?to look for assistance ?with a Drake UV3?

So once again I will ask can anyone refer me to the correct group?

Thank you

Bob Kd6gnb?

On Jan 10, 2024, at 08:40, Jim VE7RF <jim.thom@...> wrote:

?I would toss the silly 1/2 wave rectifier and at least use a FWB? or a FWD, depending on the application.? ?That 22 ohm resistor is not going to do much to speed up the RLS time, it's value is too low for that.? But for the oem 3PDT mech relay, it's good enough? and a moot point.?

Ryan NV5E writes:

I don=E2=80=99t know what all else is inside. I pulled the cover off the re=
ceiver the other day, just to take a look around. I like how it=E2=80=99s a=
ll copper in there. And thanks for the heads up on the voltage in there.

Ryan, if you can, pop the covers off the tx and rx and get some
(high resolution and well lit) pictures of the top and bottom
chassis of both, then post those to the list.

Just by eyeballing those somebody might be able to spot if a previous
owner has been golden screwdrivering in there, or if there are any
other gotchas that stand out.

I also second the advice about putting both rigs on a variac to
start. Given their age, a little babying is in order. You can buy
variacs on fleaBay for <$100, and that is money well invested. A
5A should do, although a 10A would give you more head room on the
transmitter. Watch how much current you pull through the variac.
If you run both the rx and tx through it concurrently, you need a
10A.

Do NOT buy one of the cheap chinese bright red ones you see everywhere.
They are death traps. (See the mailing list archives -- somewhere
around last spring? -- for a lively discussion on that topic.)

Note the variac will not carry the power supply for the amp. For
that you might consider just pre-emptively recapping the power
supply. But take a look inside the PSU first, as the former owner
might have done that already.

And finally, as others have said, buy or download the manuals for
everything and (re-)read them until you have them memorized :-)

--lyndon

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Well hi y’all?

I would toss the silly 1/2 wave rectifier and at least use a FWB? or a FWD, depending on the application.? ?That 22 ohm resistor is not going to do much to speed up the RLS time, it's value is too low for that.? But for the oem 3PDT mech relay, it's good enough? and a moot point.?

I currently have switching set up through my C-4 to use the amp with the 7610, plus my B Line and TR7.

Jim that's good to know. Thank you for that information.

Joe ki5o?

If you cable the MUTE connector on the RX to the RCVR MUTE on the TX that will take care of your Mute function. You need to set the Function knob on the RX to EXT MUTE. You also need a cable between RCVR ANT on the TX to ANT on the RX. Then the pair will work together.

I recommend you spend some time studying the manuals with the radios in front of you. You will learn a lot. This is how we did it back in the days before computers came with radios inside them. It's fun stuff! Some would say it's REAL radio.

73

-Jim
NU0C

On Tue, 09 Jan 2024 19:03:37 -0800
"Ryan NV5E" <ryanjones2150@...> wrote:

David, I tried a few different configurations with the cables. What was on there was a set of colorful RCA cables that had it written on the cable what all was hooked to what, including that mute cable between the transmitter and receiver. I decided to use the cables that have the yellow tags on it from the box of drake stuff it came with. I’ll try shorting that mute plug again.

--

73

-Jim
NU0C

I don’t know what all else is inside. I pulled the cover off the receiver the other day, just to take a look around. I like how it’s all copper in there. And thanks for the heads up on the voltage in there.?

I have no idea what’s supposed to be in the thing and what’s not supposed to be. There are a few spots of corrosion on the board from who knows what. As was pointed out, they sat on a book shelf for quite a long time until I got them. I’ve had them under power for a few days from the drake power supply that came with the radios.

David, I tried a few different configurations with the cables. What was on there was a set of colorful RCA cables that had it written on the cable what all was hooked to what, including that mute cable between the transmitter and receiver. I decided to use the cables that have the yellow tags on it from the box of drake stuff it came with. I’ll try shorting that mute plug again.?

I’ll take another stab at it tomorrow when I get home from the fire house. I’m also going to flip the receiver over and open it up to take a look at the other side of that speaker socket. I have a couple more things to move off the work bench from this estate then I’ll have some more room to spread out some.?

Something else interesting, I have the original sales receipt for the amplifier from 1978. I’m guessing it’s was bought new then. The amp, power supply and some coax cost the original buyer almost $1000. By today’s money, that’s about $4600. So this amp was a very expensive piece of gear back then. I’ll go through the manual closely, maybe I can find the radio sales receipt in there too. That would be pretty cool.?

Ryan,
Welcome to the group.? You have a great rig there.? Your are getting excellent advice from this group, there are many experts on here that will get you any help you
need!

In addition to the rare low frequency converter, I see a little black box to the right of the stacked Drakes.? Could this be a rare FS-4 synthesizer unit?? I see in aux
xtal slot 5? a non-xtal, looks like the plug for the FS-4.? If you have it, the FS-4 is worth another $300 or so.
73,
Gary
WB6OGD

Your 4LF looks a lot like a 2LF built on a better PC board.

73

-Jim
NU0C

On Tue, 09 Jan 2024 16:58:16 -0800
"Ryan NV5E" <ryanjones2150@...> wrote:

A lot to unpack here already, boys. I appreciate it!

David, I may take you up on that invite....be careful what you offer!

I wasn’t planning to drive the amp with another radio. If I end up keeping this set, I’d use it then.

I will try the suggestions to get the receive to work and follow up here.

I run a welding and machine shop outside of my full time job, which is where this radio set is currently sitting, right on my fab table. I need to move it. I have no radio gear active in the house. My “rack” is in the shop with me, since I’m out here most of the time anyway. I darn sure don’t want to be out here cutting, welding and grinding with this gear sitting in the middle of the shop!

I’m going to attempt to post a few pictures and see how it goes here. On the back you’ll see the 4LF. I actually have the leaflet for it and the books in a nice neat folder. I’ll take y’all’s advice and move forward.

If I decide to put it up for sale, i‘ll offer it up here first since y’all have been so open and helpful.

anyone have any idea what that 4LF might be worth being a rare Drake item? Surely there’s a serious collector out there that’s in dire need of one of these!

--

73

-Jim
NU0C

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It most certainly is true. The L4B and the L7 do not need a keying relay between the radio and the L4, L4B, or the L7.

I just sent out a new message.

Jim W7RY

I heard somewhere that the L-4B’s keying relay is only around 30V. Can anyone verify?

Steve Wedge, W1ES/4

Time flies like an arrow. Fruit flies like a banana.

Sent from for iOS

On Tue, Jan 9, 2024 at 19:59, Joe - W7RKN <w7rkn.7@...> wrote:

Hmmmm…

?

闯辞别…奥丑测?

?

I have a TS890s and for 6 months drove my L4-B with it. Granted I did use an Ameritron ARB704 as an intermediary. The only mod to the amplifier was running a Peter Dahl transformer in the Power Supply, which upped the high voltage a wee (sic) bit.

?

Joe – W7RKN

?

From: [email protected] [mailto:[email protected]] On Behalf Of Joe KI5O
Subject: Re: [DRAKE-RADIO] New to me drake 4 twins

?

Ryan it sounds like you have a great set. My only worries are making sure you have a soft key board installed on the L4B if you are using a newer radio to drive the amp.?

These lots of fun to learn with, and we are fortunate to have such a great group here as a resource.

Joe ki5o?

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Hello Joe! The ARB704 interface that you referenced performs the same function as an internal soft key to install in the L4B. Both are intended to? protect the newer rigs from the higher keying voltage.?

Have a great night!
Joe