D&a Raider grid tune question

[KK4MSA]

anyone here familiar with the Raider?
I've got one here I brought back to life and its got about 100w carrier but swings back a bit, and I've got high swr between the radio and amplifier. the output coil has been trimmed and the band switch bypassed, but the input grid tune circuit is stock. is there a common mod for this for 11m only? nothing available online and can't even find pics of one with a clear view of the input.

 

[BJ radionut]

D&A Raider info ????

whats the typical dead key and swing input and output for a D&A raider amp ? it has 4 6LQ6 tubes . D&A MANUFACTURING (SCOTTSBLUFF NEBRASCA) i had a tube amp about 30 years ago but i forget ow to do the tune plate and voltage grid stuff for the band im on . anyone care to remind me or link to...

www.worldwidedx.com

 

[BJ radionut]

D&A Mfg. Raider

 

[Dr_DX]

Here is the original schematic. Don't know if it helps any.

 

[nomadradio]

Is this the 'late' version with a band selector on the front?

The original gray Raider was straight-ahead 11 meters.

The band selector was a fig leaf over the private parts. It got them under the FCC's radar until 1979, the year 10 meters disappeared from legal ham linears. The tightened linear rules put D&A and Brewer (Varmint) out of that business. Maco just went underground, building TRS-80 computer accessories by day, when feds are on the clock. The linears got built 2nd shift when feds are back at their hotel.

The Palomar 300A is this way, has a three-band selector and pi-net coils for three bands. But the input circuit is 11 (or 10) meters only.

If this one has the band selector, the 'grid tune' input circuit is 11 or 10 meters only. You set it by putting a SWR meter and coax jumper between the radio and the Raider's radio jack. The grid tune gets set for minimum SWR when the amplifier is keyed and tuned for max modulated power.

What frequency do you want to use it for?

73

 

[KK4MSA]

its the gray one with the band switch on the front. Someone removed the old coil and trimmed it. band switch is bypassed. i got the swr down by moving and trimming the input wires around the coil. this thing was given to me for parts, but the tubes were good, so I said I'd give it a shot. got it up and going and seeing about 65w carrier, and backward swing to 45 50 or so. everything checks good in the amp so I'm figuring it's the relay as that was the original problem why it "wasn't working" and given to me as parts. I've cleaned it and tried to fix the relay but its just junk. and a 120v dc relay is unobtanium. so I'm not sure if I'm going to put the time into it to install another relay of some sort. surely there has to be a common replacement mod for these, i cant be the only one that has had to replace a relay. however, I can't find anything online about it so it may just go back for parts.

 

[nomadradio]

120v dc relay is unobtanium

This listing says he has two of them left.
https://www.ebay.com/itm/1736318452...pid=5336136228&customid=&toolid=10001&mkevt=1

And this one says he still has three.
https://www.ebay.com/itm/2027295389...pid=5336136228&customid=&toolid=10001&mkevt=1

If it was me I'd rectify/double the 6 Volt AC heater power to get 12 Volts DC, use a 12-Volt relay and a transistor keying circuit. I'm not fond of using a tube to key the relay.

And Murphy's Law says that a tube will go "poof" within a day or three of finally getting it "right" . Spare tubes serve as a hedge against Murphy's Law.

73

 

[YardDog]

got it up and going and seeing about 65w carrier, and backward swing to 45 50 or so.

What radio and meter are you using? My Icom and Yeasu will both show an AM carrier, then drop back when you modulate if the meter is reading RMS.

 

[jtrouter]

D&A Raider info ????

whats the typical dead key and swing input and output for a D&A raider amp ? it has 4 6LQ6 tubes . D&A MANUFACTURING (SCOTTSBLUFF NEBRASCA) i had a tube amp about 30 years ago but i forget ow to do the tune plate and voltage grid stuff for the band im on . anyone care to remind me or link to...

www.worldwidedx.com

First thing is the Raiders "normally" do not use 6LQ6 tubes, They normally do not have tubes that use plate caps on top. they normally use 6JR6,6JG6,6JT6 tubes or similar. I have seen a few that have been modified to use 6LQ6 or 6KM6 tubes but none of the half dozen that i have had came with those. As far as the Amp swinging backwards if you have a 100 watt carrier that is to high, Use the load and tune to set the amp up as Nomadaudio has described in other postings or tune it up using a fully loud tone and by switching between the load and tune controls to obtain the highest wattage switching between the two knobs with no more than 15 seconds of audio and then a 30 second break between each attempt to allow the tubes to cool down between each adjustment. Depending on the condition of the tubes you should endup with appox 150 watts peak or PEP and a carrier of 50 watts avg.
You should drive it with a carrier of 3 watts. In a perfect world your carrier would be
1/4 of you PEP watts output. Unfortunately i have probably rambled on too much and did a poor job of explaining this.

 

[KK4MSA]

I never said my amp had 6lq6s, that guy copied and pasted that from another post, I'm not sure why, it had nothing to do with my original question. read my original post, nothing about 6lq6s.... I originally asked if there was a common modification for the input circuit, and made a comment about backward swing, wasn't looking for an answer on that, just a comment within the post. that 6lq6 stuff was from another post that has nothing to do with me. Nomad pretty much answered my question and then shared an ebay link to some replacement relays because i commented about that as well.

 

[YardDog]

I originally asked if there was a common modification for the input circuit, and made a comment about backward swing, wasn't looking for an answer on that

Wasn't trying to piss you off. Originally you said you had 100w carrier swinging backwards. Later you changed to 65w swinging backwards. My "Question" wasn't intended to be a "Solution". I simply asked a question about the radio and meter being used.

 

[KK4MSA]

my last post was referencing jtrouters reply yard dog.
radio was bench cobra 29 2w carrier 10w pep, lp500 and a b43